Renewable Energy Handbook 2020 Windpower Engineering & Development

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The technical resource for wind profitability

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WINDPOWER ENGINEERING & DEVELOPMENT • 2020 RENEWABLE ENERGY HANDBOOK

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TABLE OF CONTENTS

SOLAR POWER | WIND POWER

WHAT’S INSIDE

THE 2020 RENEWABLE ENERGY HANDBOOK

SOLAR POWER

WIND POWER

Solar Market Overview............................................ 09

Wind Market Overview.............................................57

Solar Stats.................................................................... 10

Wind Stats................................................................... 58

Solar Technology

Wind Technology

Cables ...................................................................... 12

Bolting...................................................................... 60

Carports ................................................................... 16

Cables ..................................................................... 63

Combiner Boxes .................................................... 18

Blade Composites ................................................ 66

Enclosures .............................................................. 21

Filters ...................................................................... 68

Monitoring .............................................................. 24

Lubricants ...............................................................70

Panels ..................................................................... 28

Slip Rings ................................................................72

Racking ................................................................... 32 Inverters ................................................................. 36 Solar Installation

Wind Installation Construction ...........................................................75 O&M .........................................................................77

Construction .......................................................... 42 Labor ....................................................................... 48 Top Solar Products ................................................... 52 4

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Technology • Development • Installation

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SOLARPOWER

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SOLAR POWER

MARKET OVERVIEW

WELCOME TO THE SOLAR+ DECADE SOLAR POWER ALONE is capable of lowering electric bills and greening the environment, but for it to be most effective at keeping the lights on in this time of climate change and voluntary blackouts, it must be paired with storage.

SEIA has proclaimed 2020 to 2030 to be the Solar+ Decade and set a goal for solar to comprise 20% of all U.S. electricity generation by 2030 instead of its current 2.7% share. The group plans to accomplish this ambitious goal through "aggressive collaboration" with stakeholders in wind, storage and other industries.

The solar industry continues to reach milestones on its own. According to Wood Mackenzie's "2019 U.S. Solar Market Insight Report," the utility solar pipeline hit a record of 37.9 GW in September 2019.

Utilities like Ameren and companies like Microsoft contributed to this achievement with huge procurements, like Microsoft’s 150-MW solar array being built to power two data centers in Arizona.

The U.S. Energy Information Administration (EIA) found that solar, including small-scale PV systems, grew 13.7% in 2019 compared to the first eight months of 2018. Small-scale solar provided nearly one third of total solar generation and distributed solar as a whole grew more than any other energy source.

“It’s no surprise that the U.S. solar pipeline is surging as costs continue to fall and solar becomes the lowest cost option for utilities, corporations and families,” said Abigail Ross Hopper, president and

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CEO of SEIA. “However, as we push for solar to represent 20% of U.S. electricity generation by 2030, smart policies like an extension of the solar Investment Tax Credit will be critical to reach this goal.”

SEIA and other solar advocates are working hard to extend the ITC to make sure this growth continues in all solar sectors. Wood Mackenzie and SEIA forecasted that extending it would produce $87 billion in new private sector investment and add 113,000 more jobs over baseline estimates by 2030. It also found that an extension would generate an additional 82 GW of solar deployment over the next decade, with 63 GW coming from the utility-scale sector.

Residential solar also grew 3% quarter-over-quarter and 8% year-overyear in 2019 as it continued its rebound from 2018. Residential storage had a milestone year, hitting its biggest quarter ever in Q2 with 35 MW of installations.

“The nascent energy storage market in the U.S. continues to grow in fits and starts,” said Dan Finn-Foley, head of energy storage for Wood Mackenzie. “But signposts such as the record residential storage quarter, massive FTM pipeline growth and innovative policies such as the Massachusetts Clean Peak [Energy] Standard point toward an industry that is maturing and should stabilize at scale over the next two years.”

There's no stopping solar, but as the climate changes and the effects compromise the grid in more and more ways, energy storage must be part of the equation. SPW

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TOP SOLAR STATS There’s a lot to consider when selecting a state in which to do solar business.

Here’s an easy way to look at which states are excelling in the industry and in what ways.

TOP STATES FOR CUMULATIVE SOLAR CAPACITY THROUGH Q2 2019 • • • • •

California (25,016 MW) North Carolina (5,467 MW) Arizona (3,788 MW) Nevada (3,452 MW) Florida (3,156 MW)

TOP STATES BY SOLAR CAPACITY INSTALLED IN 2018 • • • • •

California (2,408.5 MW) Florida (971.5 MW) North Carolina (759.7 MW) Texas (509.4 MW) Minnesota (269.4 MW)

TOP UTILITIES BY ANNUAL SOLAR ADDITIONS IN 2018 • • • • •

PG&E – California (630 MW) FPL – Florida (626.8 MW) SCE – California (440.7 MW) Duke – North Carolina (436.3 MW) Xcel – Minnesota (269.4 MW)

TOP STATES FOR SOLAR EMPLOYMENT IN 2018 • • • • •

California (76,838) Florida (10,358) Massachusetts (10,210) New York (9,729) Texas (9,612)

TOP STATES FOR SOLAR JOB GROWTH OVER 2017 • • • • •

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Kansas (66% growth) North Dakota (60% growth) Illinois (37%) Wyoming (32%) Montana (31%)

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TOP STATES BY PERCENTAGE OF SOLAR JOBS HELD BY VETERANS IN 2018

TOP STATES BY PERCENTAGE OF SOLAR JOBS HELD BY WOMEN IN 2018

•

•

• • • •

North Dakota (17.7%) South Dakota (15.7%) Wyoming (15.5%) Iowa (15.4%) Texas (15.4%)

• • • •

Puerto Rico (45.1%) Vermont (43.9%) Louisiana (42.3%) South Dakota (40.4%) Montana (38.4%)

TOP STATES FOR SOLAR ENERGY'S SHARE OF STATE ELECTRICITY GENERATION IN 2018 •

• • • •

District of Columbia (48.1%) California (18.6%) Nevada (12.5%) Vermont (12%) Hawaii (11.6%)

D.C.

Information from SEIA, SEPA, The Solar Foundation

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SOLAR POWER WORLD • 2020 RENEWABLE ENERGY HANDBOOK

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TECHNOLOGY • CABLES

SOLAR POWER

ADVANCED MODULE AND RACKING DESIGNS CALL FOR NEW WIRE MANAGEMENT CONSIDERATIONS AN INTERVIEW WITH NICK KORTH • PRODUCT MARKETING MANAGER OF ENERGIES • HELLERMANNTYTON

HELLERMANNTYTON manufactures cable management products and identification systems for a number of industries, including solar and wind.

The company’s engineered solutions are designed and constructed to meet the strictest quality standards and last in the harshest conditions — from desert solar environments to salt-sprayed offshore wind farms.

HellermannTyton formed in 1969 in Wisconsin and today operates in 39 countries. We talked with Nick Korth, product marketing manager of energies, to get some insight into how cable management is evolving on solar projects.

What is the reason for wire management on solar projects?

Wire management is critical on all solar projects. Whether residential,

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commercial or utility-scale, protecting the wires is critical to long operating life. A lack of wire management, or wire management strategy for that matter, including misapplication or poor product design, can lead to long-term issues, including fires.

Are there general rules when it comes to wire management?

There is no one rule of thumb when it comes to wire management. Safety of the wires is the No. 1 priority, and there are many ways for an installer to achieve this goal. At HellermannTyton, we have written several white papers and best-practice guides, presented webinars to foster these standards, and SEIA is working on best practices as part of their committee work. With that said, best practices are only suggestions, and within the framework

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of the NEC, there is little that “polices” the actual routing and protection of the cabling.

One example of this is the new addition to the National Electric Code, 690.31(C)(1): “Exposed cables shall be supported and secured at intervals not to exceed 600 mm (24 in.) by cable ties, straps, hangers or similar fittings listed and identified for securement and support in outdoor locations.”

While this reference is providing a guideline on where to place wire management, it will not instruct installers how to install the product.

It will have significant impact on the industry moving forward, because in places like the back of a solar module or frameless modules, there are no wire management attachment points.

That is where HellermannTyton likes to educate our customers,

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TECHNOLOGY • CABLES

take a hands-on approach when golden rows are being installed, and be a true solutions provider instead of a part manufacturer. Each utility-scale project is unique, be it the module or racking or BOS design, so consulting with our customers can help prevent issues during installation and save on maintenance costs down the road.

What are the pros and cons of plastic and metal fasteners on solar applications?

This is a conversation we have with every one of our customers.

Many considerations go into selecting the right material for wire management. How confident are you that the product will be installed correctly?

What environmental factors will affect the installation? What type of racking and modules are being used?

As one of the world’s largest manufacturers of cable ties and having nearly 70,000 different parts, we have a solution for virtually any situation. Plastic materials provide safety that metal can’t, but they have lower potential longevity. There are many different grades of plastic available today — Acetal, Nylon 6, Nylon 12, PVDF — and many different modifiers that can alter the characteristics of those base materials. These modifiers can help plastics survive better in direct sunlight or keep moisture levels stable to avoid brittleness.

And yet, developers and installers have incurred exorbitant costs because an inferior plastic was specified or inappropriately installed, and the wire management must be completely replaced. One truck roll on a residential installation can eliminate much of the profit and having to replace 100,000 cable ties represents a lot of labor expense, all for a part that can cost as little as a penny. So, they specify metal. Metal and coated metal products provide the assurance that the product will last 25 years in most circumstances, but metal can easily damage cable jackets and a ground fault can lead to more serious issues. Coated metal parts create a “false security” of long life, but the plastic that insulates the metal from the wires is subject to metal-toconductor failures.

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SOLAR POWER

Consequently, both metal and plastic have their benefits and flaws. By having a good design plan in choosing the proper material for the application and having a good follow-up O&M plan to observe and monitor, our customers have been happy choosing plastic wire management solutions.

As module designs advance, how too does wire management?

Modules are difficult to design wire management around. Every module is a little different, be it the module mounting hole, the edge thickness of the frame or even the frame design. HellermannTyton has a variety of solutions for module level wire management to address these differences.

That is not always the case with utility-scale projects. As the utility-scale market transitions to less material, it also creates fewer routing options. Punched holes are cost prohibitive or impede structural integrity, and certain metal profiles are difficult to attach to. With the new changes to NEC 2020 and 690.31(C)(1), it will be even more of a challenge. Routing wires along the torque tube will become more prominent. One reason is the lack of edges and holes to mount wire management.

Another is split junction boxes that are often located close to the center of the module. Often a MIB or support bracket for the module on a single-axis tracker interferes with typical wire management placement and creates difficulty attaching to modules. And with bifacial projects, developers want to squeeze every watt of power out of their projects, and shading of the back of the modules tends to be avoided. This brings new challenges because racking manufacturers do not typically allow for holes or anything being attached to the torque tube. Heat and movement are serious environmental concerns along the torque tube. With metal pieces that large, they can move throughout the day as the array thermocycles and can often get as hot as 160°F. We are seeing a trend of new products (racking and modules) whose designers seem to have forgotten that wire management even happens. There must be an attachment point for wire management, and designers of new module frames and racking structures are not considering the available range of parts in their designs.

This realization often doesn’t happen until structures are being erected and modules attached — a bad time to realize there are few options currently available. SPW

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TECHNOLOGY • CARPORTS

SOLAR POWER

HM &P

A Q&A ON SOLAR CARPORTS

AN INTERVIEW WITH JOHN FREDERICK • VP OF SALES AND MARKETING • POLY-TEX

SOLAR CARPORTS are becoming an increasingly popular choice for commercial customers that may not have the roof space for solar. Parking lots and parking garages are underutilized areas perfect for solar generation. We talked with John Frederick, VP of sales and marketing for Poly-Tex, a Minnesota-based solar carport manufacturer, about his company's background and the latest trends in solar canopies.

What is Poly-Tex Solar's background?

Poly-Tex has been in business for over 30 years. The company’s historical (and current) product lines include greenhouses and shade structures. Solar carports looked like a natural fit for our engineering and manufacturing capabilities so we started addressing these solar structures several years ago.

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What type of solar canopies/carports do you produce?

Poly-Tex provides a number of different designs that cover rows of single or double parking spaces. We also have designs that can cover an entire parking lot including the driving lanes.

What type of customer generally looks into solar carports?

Carports are becoming more popular nationwide. Many retail and commercial business owners are looking to make their commitment to sustainability more visible to the public. They may also have rooftops that aren’t well suited to solar, and carports are a good alternative. Cities are becoming more interested in putting solar on underutilized assets such as public parking lots and parking garages.

What are the pros and cons of single cantilevers and dual cantilevers?

A single cantilever carport is used to cover a single row of parking stalls. A dual cantilever carport is used to cover two rows of parking stalls. Typically a dual cantilever carport will be more cost effective.

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SOLAR POWER

What are the installation requirements with tilted plane arrays?

For parking lot applications, the installation requirements are similar to other types of carport structures. The biggest difference comes from the ability to also cover the drive lanes (as well as the parking stalls) with solar panels. This allows a developer to maximize the amount of solar production on a particular parking lot or garage.

How do you handle foundations in parking garage installations?

Parking garage installations are unique because the vertical supports for the carport structure must align with the support structure for the parking garage. This typically requires a 60- to 70-ft clear span distance. Poly-Tex created the Tri-Plane Truss

CARPORTS • TECHNOLOGY

design to cost effectively address the long clear span requirements. Poly-Tex’s modular approach (no individual component is over 25-ft long) reduces crane operation time and addresses potential garage weight restrictions.

What trends are you seeing with carport installations?

We are seeing a trend to cover the entire parking lot or garage with solar panels.

This provides better protection for vehicles and better economics for the project. This does drive the need for longer spans to accomplish this. SPW

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TECHNOLOGY • COMBINER BOXES

SOLAR POWER

A FEW SIMPLE SAFETY LABELS CAN MAKE A BIG DIFFERENCE IN KEEPING SOLAR WORKERS SAFE TIM O’CONNOR • VP OF SALES • LEM PRODUCTS

OVER THE PAST DECADE, America’s solar energy industry has grown rapidly — more than doubling its workforce. There are now more than 242,000 U.S. solar workers, who all want to safely make it home at the end of every day. Although protecting that many workers from a multitude of hazards may seem like a daunting task, it does not need to be. Training programs and compliance with OSHA safety standards keep workers informed and can prevent accidents.

While solar energy is a growing industry, the hazards that workers face are not unique. That being said, many

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solar energy standards are only now being written and developed, 30 to 40 years after the industry was first established. Fortunately, OSHA is leading the charge and has many standards that solar companies should reference when establishing best practices to safeguard against hazards.

Minimizing human error Unsurprisingly, human error accounts for a significant percentage of accidents across all industries, including solar. Cramming too many wires into an electrical box, creating a cluttered work area that is not up to code, not following equipment standards and inadequate instructions on labeling and signage are among the most common errors that can lead to injuries.

One of the best defenses against such hazards is extensive, ongoing employee training. Solar companies should monitor frequently for new standards and adjust their best practices and training programs as needed to ensure that their employees are well-versed in the most up-to-date procedures and work in compliance with them.

Utilization of industrial safety identification in the form of safety labels and site safety signage is a key way to prevent human error and alert workers to possible hazards.

Continuing safety training programs and OSHA-compliant industrial safety identification serve as easily accessible references for best practices and also bring safety to the forefront of employees’ minds every time they step into a work area or prepare to use equipment.

Last but certainly not least, businesses should also implement an organizational program such as the Kaizen or 5S method — sort, set in order, shine, standardize and sustain — to keep work areas tidy and free of trip hazards. Employees will not only be safer but will also

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SOLAR POWER

COMBINER BOXES • TECHNOLOGY

High Performance Solar Modules

perform better and work more efficiently.

Protecting against electrical hazards Arc flash burn is a common electrical hazard caused by an arc fault, or electrical explosion. Arc flash burn refers to the light and heat produced by the fault, and it can be fatal. Solar workers are particularly at risk of experiencing arc flash burn when attaching panels to an electric circuit.

Arc faults also commonly occur at junction boxes for a multitude of reasons. Turning the boxes on or off or changing the direction of the flow of power inside the boxes can trigger faults. Additional causes include wiring failures, excessive DC current, overheating, lack of or improper grounding, improper connectors and even rodent infestations.

To keep workers safe, electrical equipment and surrounding areas should be thoroughly labeled with durable, weather and fade resistant

2020 RENEWABLE ENERGY HANDBOOK

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TECHNOLOGY • COMBINER BOXES

servicing, the program is estimated to prevent more than 50,000 injuries and fatalities every year. Employees performing maintenance first deactivate and then “lockout tagout” equipment so that no one else can access and reactivate it. This program prevents accidental equipment activation and can prevent serious injury.

When purchasing lockout tagout tags, companies should consider quality and durability as well as for which kinds of equipment the tags will be used.

Tags can be made from many different materials and can be designed for one time use or repeated use. Vinyl tag construction is the most durable. warning labels, and clear procedures should be posted to avoid arc fault and other hazards.

Industrial safety identification signage alerts workers to be mindful of overhead power lines and maintain a buffer of at least 10 ft at all times to avoid electrocution or burns. Falls from this height may be deadly, so it is vital to ensure workers are aware of these serious conditions. All industrial safety identification should be made to resist fading and product disintegration.

Properly maintaining equipment Servicing equipment regularly is another critical way to prevent electrical accidents by ensuring the equipment is clean and working properly.

Maintenance, repair and operations should be a cornerstone of companies’ safety agendas. To safeguard against them, businesses should implement a lockout tagout program.

Designed to protect workers from the release of hazardous energy during

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Preventing fall hazards Given the nature of the solar industry, falls are an inherent risk for workers.

However, they are preventable if companies follow proper safety procedures. Per OSHA guidelines, workers exposed to fall hazards of 6 ft (if installing panels) or 4 ft (if performing maintenance) must be protected by guardrails, safety nets or personal fall arrest systems like harnesses. Danger, caution or notice signs keep workers alerted to many possible hazards and the severity of those hazards. OSHA has clear guidelines for industrial safety signage.

Workers should also use lifting equipment, such as cranes and hoists, and always consult the safety labels for proper operational instructions. Accidents primarily occur due to improper use of or

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SOLAR POWER

insufficient inspection of the equipment, which only trained personnel should operate. Under no circumstances should workers use ladders to manually carry up panels. Inspection labels should be applied upon completion of the inspection.

Environmental hazards Solar energy workers frequently contend with extreme temperatures, but they should not suffer in silence in the event of medical emergencies such as heat stroke or heat exhaustion.

Emergency contact information should be clearly posted on site safety signage.

It is critical that companies regularly review industrial warning signs to ensure signage is posted in appropriate locations on site. Industrial safety signs should be printed with materials that will last in prolonged sun exposure and extreme climate conditions. Knowledge is the best defense against hazards, and employees need to be prepared to respond quickly to take care of themselves or their coworkers.

Solar workers face a variety of hazards every day, and companies are required by OSHA to provide information and training that will keep them safe. By following OSHA standards, implementing comprehensive training programs, providing safety signage and continually reassessing best practices, businesses can ensure their employees are always protected on the job. SPW

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12/12/19 11:06 AM

SOLAR POWER

ENCLOSURES • TECHNOLOGY

THE IMPORTANCE OF THERMAL MANAGEMENT OF STATIONARY LITHIUM-ION ENERGY STORAGE ENCLOSURES CHRIS BOYER, PHD, PE • BUSINESS DEVELOPMENT DIRECTOR • SABRE INDUSTRIES

AN INCREASE IN battery energy storage system (BESS) deployments reveal the importance of successful cooling design.

Unique challenges of lithium-ion battery systems require careful design. The low prescribed battery operating temperature (20° to 25°C) requires a refrigeration cooling system rather than direct ambient air cooling. The narrow allowable temperature variation — no more than 5°C between hottest and coldest battery — requires near perfect air distribution. And, the rapid changes in power with time require tight control. Without proper thermal management, overheating cells will degrade, malfunction or even catch fire.

Several modeling tools aid in the design process to ensure good designs. These include: 1. Overall mass and energy balance equations for selection of cooling equipment sizes; 2. Transient finite element analysis (FEA) for studying the transient behavior and control methods; and, 3. Computational fluid dynamics (CFD) software for evaluating the air flow distribution and the resulting temperature variances. solarpowerworldonline.com

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1. Sizing the cooling system with overall energy and mass balances Getting the right capacity and turn-down capabilities for BESS thermal control will result in better performance and a longer life for the batteries.

Under-sizing the cooling system can lead to battery overheating. Over-sizing the cooling system can lead to short cycling of the cooling system and large air temperature swings when the unit turns on and off.

Heat generated by the batteries Heat generation from the batteries is the largest load and therefore the most important to predict accurately. Heat results from reaction entropy and activation energy losses, electrical and ionic resistance, and chemical transport. The heat generated is typically flat between 20% and 80% state of charge (SoC). Heat generation increases SOLAR POWER WORLD • 2020 RENEWABLE ENERGY HANDBOOK

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SOLAR POWER

significantly as a discharge approaches 0 SoC and when the charge approaches 100% SoC, as shown in Figure 1.

Because of degradation, the heat generation increases over the life of a project. Increases of 35% to 70% have been reported by battery companies.

Other heat loads The high-voltage DC bus and cabling system generates resistive heat and is typically designed to be about 0.25% of the maximum DC power. Heat generated by lighting, communications equipment, power supplies and controllers remains relatively constant with time at about 500 W to 1 kW of heat.

Heat also comes in from the external environment.

Commercial HVAC sizing software accurately calculates the environmental heat load.

HVAC equipment selection HVAC capacity ratings are based on a set of nominal conditions. The actual capacity of the HVAC is lower than the nominal rating in most energy storage applications due to hotter outdoor temperatures, lower interior set point temperatures and lower humidity. If operating in a hot desert, the actual capacity of an air conditioner may only be 50% of the nominal capacity, or even less as the evaporator and condenser coils get soiled. As a general rule of thumb for energy storage, the HVAC equipment nominal rating should be 150% larger than the sensible cooling load required based on the calculations above.

Figure 2.

Figure 1.

Heat transfer between the cooling air and battery modules Today, most stationary BESS systems use air as the medium to cool batteries. In addition to a properly sized cooling system for the enclosure, the modules must also have a properly designed method for locally transferring heat into the cooling air.

In order to keep the battery below a maximum temperature, two conditions must be met. First, the overall heat transfer coefficient must be sufficient. Second, the air flow volume (passive or active) past the modules must be sufficient to absorb the heat generated.

These two conditions must be checked, and if they fail, then no amount of HVAC capacity can keep the battery cool.

If the limitation is conduction of the heat through the module to the surface and from the surface to the air, then the module must be redesigned for better heat transfer.

2. Transient considerations for sizing the cooling system Figure 2 shows examples of load profiles for different BESS applications. A transient analysis studies how the HVAC system affects the battery temperature as the load changes.

The transient thermal model presented has been used to evaluate many design decisions, such as: • Determine the amount of cooling required in a particular usage case based on the application’s load profile; • Determine if cooling staging is required and, if so, what levels of staging; • Determine the effects of different temperature control methods; • Evaluate the effectiveness of adjusting thermal masses in both the module and the enclosure; • Evaluate the effectiveness of adjusting air flows in the enclosure and in the modules.

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ENCLOSURES • TECHNOLOGY

3. Achieving balanced air distribution with CFD Another key aspect of the cooling system is how the air is ducted through the enclosure to keep the batteries within an allowable temperature variance. CFD analysis excels at calculating spatial values for temperature, static pressure, air velocity and air flow direction. CFD analysis helps make critical design decisions, such as: • Verify sufficient cross-section area for air flow throughout the enclosure, • Select locations for air barriers and deflectors, • Determine optimum size, shape and register locations for supply ducts, • Provide direction for optimizing the vane positions in supply registers, • Determine significance and location for air barriers between or around equipment, and • Determine the effectiveness of additional fans/blowers in the enclosure to augment the HVAC. Conclusion Batteries generate heat like other electrical equipment, however, manufacturer performance warranties require a low temperature and a very narrow window in which the batteries can operate. Although designing the thermal management system for a battery energy storage enclosure presents these unique challenges, the tools presented here are being used with success. SPW This story was edited and condensed for space. Find a longer version, complete with mathematical equations and additional charts, at solarpowerworldonline.com.

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TECHNOLOGY • MONITORING

SOLAR POWER

ADVANCED SCADA FUNCTIONALITY HELPS SOLAR OPERATORS MANAGE THE FUTURE BOB WOOD • CHIEF OPERATING OFFICER AND CHIEF TECHNOLOGY OFFICER • TRIMARK ASSOCIATES

TECHNOLOGY EXISTS to improve our lives. For those in the energy industry, SCADA system technology helps to operate solar sites. An acronym for Supervisory Control and Data Acquisition, SCADA is a system that links together numerous hardware and software components of a site in order to easily monitor, control and analyze performance. Those components continue to expand, helping solar operators analyze all relevant solar project data in one place.

SCADA: The basics All SCADA systems monitor data from a plethora of devices, including meters, inverters, weather stations, trackers, DC strings and substation equipment.

At a basic level, these systems provide actionable information to determine whether solar plant equipment is performing as expected, identifying offline and malfunctioning equipment.

System operators and performance engineers can analyze the SCADA data and determine when to deploy technicians to resolve any issues.

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When plant owners manage multiple sites, it’s critical to employ more automated methods of identifying and addressing performance issues.

Also, with tight operating margins, they need an economical solution to analyze and investigate root causes of issues. SCADA addresses these necessities, simplifying how owners run their sites.

As analytics, widespread services integration and numerous other technologies continue to advance, leveraging SCADA to improve a site’s operations without increasing costs is as simple as ever.

Details in the data Traditional SCADA systems constantly monitor equipment at a site and record sampled data to a local historian. The real-time data is visually represented on operator screens and is used to evaluate alarm conditions.

Most systems provide a summary of the collected data to show trends and identify anomalies, as well as showcase design queries and reports

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that summarize the data for operational maintenance and management. The data is exported from the historian regularly for further analysis in other data management systems, where it is augmented with rate schedule details, maintenance management data, modeled data, weather data and more.

Since a SCADA system already stores plant operational data, it makes sense to incorporate advanced analytics and performance management functionality into the same SCADA system rather than add external systems. This reduces overall operation complexities and costs. On top of this, collecting data in real time allows for performance issues at plants to be more readily addressed.

Effortless management To determine a baseline of how a site should perform, an engineering analysis is typically conducted before and after construction. This information, which is used to calculate actual and projected performance, is part of a plant’s overall financial management reporting. SCADA systems should incorporate a plant’s performance expectations and then analyze and compare that data to actual performance. Reports should show the site’s performance relative to expectations.

Taking this further, an effective SCADA system should incorporate the following functions.

• Weather forecasts: By integrating weather forecast service support, solarpowerworldonline.com

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TECHNOLOGY • MONITORING

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along with expected performance, the SCADA system can provide accurate energy forecasts, providing insight into data and sensor calibration.

Device-level analysis: When performance is analyzed at the individual device level, such as individual inverter capacity, string counts and installed solar panel specifications, a SCADA system can alert operators and maintenance technicians of device performance issues and the level of impact for quick analysis.

Tracker angles: Adding calculated tracker angles into the SCADA system identifies when trackers are not tracking to the optimal angles, resulting in decreased energy production.

Lost energy analysis: Lost energy, a measure of the amount of energy that would have been produced if all devices were functioning optimally, provides historical details to analyze underperforming devices.

Rate schedules: Including Rate Schedule Awareness enables the SCADA system to know the value of the energy produced by the plant or the value of the energy not produced. This information is used to evaluate a plant’s financial performance.

With comprehensive, real-time analysis, plant owners and operators don’t need to constantly and actively look for issues at a plant. The SCADA system can provide performance-based alarms to alert operators when a site, or individual devices within that site, are not performing optimally. When managing multiple sites, resource owners and operators greatly benefit from the automated alerts from advanced SCADA systems.

An integrated system Introducing integration to a utility energy management system enables the utility to monitor critical plant functions in real-time and to incorporate Automated Generation Control (AGC) to control the plant output. With advanced SCADA systems and additional integration capabilities, automation and control can be taken a step further.

• Satellite weather/forecasting: Integrating one or multiple weather services to augment plant information with area weather observations and forecasts helps to estimate energy production from the plant.

• Meter settlement: Integrating meter reading systems ensures accuracy in settlements.

• Billing systems: With complex rate schedules, the billing process can be tedious. Having to export the SCADA system data into a separate, complex spreadsheet and then enter that data into an accounting system is time-

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consuming. However, when integrating billing into a SCADA system, this process can be automated, creating invoices without manual manipulation.

Document management: Rather than storing engineering, contract, compliance and procedure documents in a document management system, the system can be integrated into the SCADA system.

Documents can be easily accessed from the SCADA system for ease of organization and control.

Perfection through analytics Applying analytics to a solar facility provides valuable insight into the project’s performance. Presenting this data visually using graphs and reports on intuitive dashboards helps to maximize performance and outline information. For example, performance across an entire fleet can be reviewed and compared, with fleet information sorted by type and equipment.

While this type of analysis has traditionally been done on separate systems, advanced analytics are being increasingly integrated into SCADA platforms for direct data management. Cost-effectiveness aside, the ability to organize both historical and real-time data in a variety of ways — by type, model, performance, etc. — enables solar project operators to immediately adapt to recognizable trends, thereby optimizing their generation and maximizing revenue.

A lasting impact Technology is ever-evolving and SCADA systems are no exception. Already a flexible system for collecting and managing generation data from sites, SCADA systems have broadened — rather, transformed — into an all-in-one business management system that supports just about every aspect of a plant. The innovative, comprehensive functionality of this technology cannot be understated, nor can the excitement it brings to the energy industry.

Whatever the next breakthrough in SCADA may be, there is no doubt it will make the lives of site operators everywhere that much easier. SPW

solarpowerworldonline.com

12/12/19 11:55 AM

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TECHNOLOGY • PANELS

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WHAT ARE TIER 1 SOLAR PANELS? KELLY PICKEREL • EDITOR IN CHIEF • SOLAR POWER WORLD

ALL THE BIG solar panel names usually hype the fact that they are “tier 1” solar module brands. The tiered classification was first developed to show banks which panel manufacturers were legitimate and trustworthy. But the term has morphed into a marketing buzzword that solar customers may confuse with reliability, which frustrates small panel manufacturers like GreenBrilliance USA. “The focus on what you’re buying is gone.

Now it’s who you’re buying,” said GreenBrilliance president and CEO Sumit Bhatnagar. “Is branding important, or focusing on making the right parts? I choose the second.”

The official origin of the phrase “tier 1” solar panels comes from Bloomberg New Energy Finance. The group first developed the tiered system for PV modules to create a transparent differentiation among the many solar manufacturers, so financial institutions could easily determine which brands were “bankable.”

BNEF tracks past solar projects (sized over 1.5 MW) approved by banks, and the products used in those projects lend to what tier they fall into.

If projects using XYZ modules have consistently been approved for financing, then Company XYZ will likely be a tier 1 supplier.

To be considered a tier 1 module supplier on BNEF’s list, the company must have provided its own in-house manufactured brand of panels to six different projects that have been nonrecourse financed by six different banks in the last two years. The non-recourse stipulation is important, because that means the bank will take the risk of the modules failing.

That’s it though. Based on BNEF’s criteria, tier 1 modules are just those that are used in a lot of projects, and almost all established solar

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PANELS • TECHNOLOGY

companies are considered tier 1. BNEF does not publish tier 2 or tier 3 lists, so any sub-tiered lists out there are just made-up marketing terms. It’s also important to note that BNEF’s tiered system “ranks” manufacturers and not specific panel lines. Tier 1 doesn’t mean the panels are the best performing modules on the market.

“This classification is purely a measure of industry acceptance, and there are many documented examples of quality issues or bankruptcy of tier 1 manufacturers,” BNEF said in its fact sheet.

BNEF states that although manufacturers use their tier-standing in advertisements, this classification “should never replace a proper due

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diligence process in product selection.”

BNEF suggests that outside firms not familiar with the solar industry should work with technical engineers — like DNV GL and Black & Veatch — to get full reports on module manufacturers and their facilities.

GreenBrilliance USA, which is trying to break into the U.S. market with a brand-new manufacturing facility in Baltimore, Maryland, thinks the tier classification is a setback for startups.

According to the unofficial industry standards, manufacturers can’t break into the top tier until they’ve been producing many panels used in many large projects. And if customers only request tier 1 panels, that could be an issue.

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“As long as you use the right materials, if the panels are made with raw materials that are correct, if you’re not buying cheap crap from China, your panels will be top quality and they will last. Beyond that, there’s no such thing as tier 1 always going to be better,” Bhatnagar said. “If you really want a quality panel, come and see it. Don’t trust the tier 1 [label]. They still fail.”

Jonathan Camarda, president of East Coast residential installer Skyline Solar, said he bases his panel-buying choices on what is available through distributors.

“We like to use a brand that will not have manufacturing backorder delays,” he said. “Looking at the tier of panel isn’t necessarily a major point.”

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TECHNOLOGY • PANELS

Skyline Solar customers may request certain name-brands, but the company pushes manufacturers with good warranties.

“We let the homeowners know we can install whatever panel they want, and we go over the different warranties,” Camarda said.

“Homeowners feel most comfortable when you discuss the panel coming with a third-party warranty.”

That third-party warranty is also something Minnesota-based installer Winona Renewable Energy looks for. The fact that established, recognized panel companies usually offer those third-party warranties leads to Winona only buying tier 1 modules.

“I previously purchased from smaller module manufacturing companies that ended up not being financially strong, and

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they went out of business, which left my customers’ warranties voided,” said Tim Gulden, owner of Winona Renewable Energy. “I now only buy tier 1. I see that it gives my customers peace of mind when I explain why.”

The solar industry’s tiered system of ranking module manufacturers may be antiquated at this point, but its legacy still lives on. Whether a company can support third-party warranties has become a more generalized way to recognize reliable solar panels, but installers not requiring extended warranties should keep an open mind to innovative solar panel start-ups to find the best fit for projects. SPW

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TECHNOLOGY • RACKING

SOLAR POWER

Q&A WITH ANDREW WICKHAM OF SNAPNRACK ON RAIL-LESS MOUNTING SOLUTIONS AN INTERVIEW WITH ANDREW WICKHAM • MANAGER OF CUSTOMER EXPERIENCE • SNAPNRACK

RAIL-FREE or rail-less solar mounts don’t have the same market share as their railed and shared-rail cohorts but remain a viable option for sloped rooftop arrays. Panel racking attaches directly to the roof mounts instead of using a guiding rail. The rail-less system was conceived as a faster mounting option with fewer components for installers to haul onto rooftops.

Andrew Wickham, manager of customer experience at SnapNrack, said rail-free mounts are best suited for composition shingle rooftops in regions with smaller wind and snow loads. He shared with Solar Power World some history, advantages and system features for the unique mounting solution.

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What are installers typically using on pitched rooftops?

In your California markets, you'll see more rails being used because that way they only have to carry one system.

Whether it’s composition shingle or tile roofs or metal, railed works for all those and works great.

Where rail-less really becomes a benefit is in areas with jurisdictions that require rough inspection. They require that the mounting system be inspected because they want the bonding path to be inspected prior to modules being laid down. With rail-less systems, the bonding path does not exist until the modules are laid down, so it takes installs from two days to one day because they're able to install it all together prior to that inspection, as there's no rough inspection requirement.

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RACKING • TECHNOLOGY

Why were rail-less systems originally developed?

I'd say, originally, it was around the idea that they would be faster to install because they’re just installing the mounts and putting the module straight into the mount as opposed to putting a rail on the mount and putting a module on the rail. What actually happened was Zep Solar was the biggest rail-less solution provider in the United States and had a pretty good market share and then they were acquired by SolarCity. It was a pretty big acquisition and definitely hit news across the country. That created this rush from other manufacturers to create a rail-less system because SolarCity took [Zep] off the market. You had a bunch of installers out there using that system but now couldn't get products but wanted to install rail-less. So, that created this surge around other manufacturers creating rail-less systems based on the [their] efficiency benefits.

The truth of the matter is, install-time wise, rail-based systems and rail-less systems are actually very comparable.

It's not like you're seeing 25 or 50% improvement with the

rail-less system as far as efficiency. However, on the logistics side of things, not having 14-ft sticks of rail to haul up onto the roof or transport makes things a lot easier, because everything in a railless system can come in a box. So then you're able to get out to jobs and get stuff up on the roof much easier since you're just getting boxes of parts up on the roof.

What does it take to install a rail-less system?

The typical method is what's called an L-foot, which essentially is an “L” that gets lagged into the roof rafter on the bottom and then the portion of the L that comes out has a channel net where it gets bolted from the side to a rail. Then the modules rest on top of the rails, and you have module clamps that insert into the rail channel and clamp down on the modules and hold them in place.

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TECHNOLOGY • RACKING

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With rail-less mounts, how do you ensure everything is aligned since you're not working with the physical rail as guidance?

So that is one of the factors with the rail-less system that takes a lot more effort. It’s just making sure that you're snapping your lines and aligning your array properly. There are certain systems, such as our RL system, that have a 6-in. track that sits on the roof, so you have that north-to-south flexibility of moving the mounts up and down to get everything aligned properly within each row.

But it's definitely a lot more precise than with a rail-based system, whereas you just mount your two rows of rails and then the modules sit on top of them and the modules can slide up-and-down, side-to-side on the rails. However, because of the adjustability that our RL system provides with that 6-in. track, it actually makes it easier to align and more adjustable than a shared-rail system. Shared-rail systems require the highest detail of alignment because you're mounting a rail along the module edge and it has to line up perfectly for the clamps to go between the modules. SPW

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TECHNOLOGY • INVERTERS

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CPS

KELSEY MISBRENER • SENIOR EDITOR • SOLAR POWER WORLD

HOW TO CHOOSE BETWEEN STRING AND CENTRAL INVERTERS IN UTILITY-SCALE INSTALLATIONS As inverter technology evolves, so too does the decision whether to choose central or string inverters for utilityscale solar farms.

Central inverters “centralize” the plant’s power into one place.

String combiners connect wires from each row of panels together, then recombiners combine the output of the string combiners together to feed into the central inverter. Central inverter units are physically much larger than

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string inverters, use longer wires and can convert more power per unit.

String inverters are a distributed architecture for solar plants. They’re small, and each unit converts a much smaller amount of power than a central inverter. There’s an inverter sited at each row of panels, so the 10-20 input strings leading from the panels to the inverters can be much shorter.

Since string inverters are converting less power for fewer panels,

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if one string fails, the whole array’s energy is not lost, just the power from that string. Contrast that with a central inverter, where much more power is lost if one goes down.

Central inverters are less expensive than string overall for large utility-scale installations because fewer are required per site. But for smaller utility-scale projects, string inverters could win out for their easier serviceability.

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TECHNOLOGY • INVERTERS

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SOLAR POWER

Serviceability is how easily an inverter can be repaired in case of failure. Power electronics are the aspect inherently most prone to failure in a solar installation, so inverters are likely to need servicing throughout their lifespan.

Fixing central inverters requires technical expertise that many O&M technicians don’t have, said Eric Every, product manager at Yaskawa Solectria Solar. Although some installers opt to go through central inverter maintenance training, it may be a long time until they need to actually put their skills to use, and they may have forgotten what to do when that time comes. Usually if a Solectria central inverter fails, the O&M operator has to call Solectria, work with a technician to diagnose the problem, then fly the Solectria tech out to the site to fix it. If the failure happens near the end of the year, all the techs could be booked with commissioning work, Every said.

“It’s a pretty big operation to get an inverter tech on-site with the parts that they’ll likely need with the tools that they’ll need to get you back up and running,” he said.

Contrast that process with fixing a string inverter, which is small and portable and can be done by any trained electrician. Site owners often keep spare inverters and spare kits on-site to be able to swap parts or entire inverters quickly.

“If you really need the system back up and running, you can do it,” Every said.

“You’ve taken ownership of that process.”

String inverters also come with the benefit of more granular energy optimization, which is essentially the balancing of volts and amps in the power conversion. Since each unit converts power for one string instead of a larger chunk of the solar project, each inverter is better able to optimize the power for the smaller chunk, said Ed Heacox, general manager of CPS America.

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TECHNOLOGY • INVERTERS

SOLAR POWER

SPW

CPS

“With the central inverters, they typically do large chunks, maybe 2 MW of the array, and it’s less optimal,” Heacox said.

Ingeteam manufactures both string and central inverters, so it’s unbiased about what’s best for which application. Carlos Lezana, marketing and communications for solar for Ingeteam, said the company targets the 1- to 10-MW utility-scale market with its string inverters and suggests central inverters for larger projects.

“The main advantage of the central inverters is that the cost per watt is the most optimized one,” Lezana said. “That’s the cheapest option. That’s why if you go to very large utility-scale, they always go with central inverters.”

If developers are looking for an inverter solution for a 20-MW solar plant, their option would be five to seven central inverters or hundreds of string inverters, Lezana said.

The advent of 1,500-V string inverter architecture adds some complexity to the central vs. string decision. Each inverter is processing more power — whether it’s a 1,500-V central or 1,500-V string — so that means more power is lost when one inverter goes down. However, the cost savings of the increased voltage really shine in large utility-scale arrays that use central inverters.

“The larger the scale, the greater the savings,” Lezana said.

Since the upfront cost of string inverters is greater and the logistics of installing so many of them are more complicated on projects sized 10-MW and larger, central inverters will likely continue to win on very large projects, especially at a higher voltage. SPW

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INSTALLATION • CONSTRUCTION

SOLAR POWER

HARRY BENSON • DIRECTOR OF BUSINESS DEVELOPMENT • STANDARD SOLAR

HOW EARLY MONEY AND THE RIGHT FINANCIAL PARTNER CAN SMOOTH GREENFIELD DEVELOPMENT DEVELOPING A GREENFIELD SOLAR PROJECT from the beginning adds significant value and return to the project developer. That’s why there’s a rush to develop early-stage solar projects.

Greenfield development is basically the creation of a solar project where there had not previously been one. You find the property, submit an interconnection application and build the project.

Easy, right?

Well, the reality of greenfield development is far more complex than most people understand, and it takes several steps before you can put shovels into the ground. First, a full and comprehensive criticalissue analysis must be performed, with particular attention paid to the following: • Selecting a state with a solid solar program and easy to navigate and predictable permitting process.

• Understanding the local government’s views regarding solar and their permitting process.

• Selecting sites and distribution lines that will have low-cost impact or upgrades needed on the local grid.

• Securing inexpensive land leases for property that does not have trees, wetlands or suitable habitat for threatened and/or endangered species.

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Even if you have all those criteria in place, it’s still not enough to guarantee that a greenfield development will go smoothly. It’s also important that the state you choose has high electricity prices.

If prices for electricity are too low or the Solar Renewable Energy Credits (REC or SRECs) too meager, the project won’t be financially viable.

Fortunately, there are a number of states that fit that criteria.

Perhaps the best state to do business in is Massachusetts, which has a great history and program, along with high electricity prices.

Minnesota, like Massachusetts, has a strong renewable portfolio standard (RPS) and has advanced into community solar like no other state in the country. And most recently, Maryland passed a 50% RPS bill with a 14.5% solar carveout, which is expected to significantly accelerate solar in the state.

It also can’t be said enough: Check in with the local government early and often to make sure you have a full understanding of their attitude about solar projects. While people often focus on the national debates, it’s local and state regulations that really hamper the solar industry’s expansion. If you’re not up on what local regulators are thinking, you run the risk of running into rampant not-in-my-backyard-ism — leaving you without the solar project you thought you were developing.

Start your education early. Whether it’s through social media, legacy media (newspapers and radio) or showing up at town fairs and meetings, it’s incumbent on the solar developer to properly educate local officials — because once they have the wrong idea in their heads, it’s often incredibly difficult to change it back.

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INSTALLATION • CONSTRUCTION

Finally, it’s easier than ever to secure good land leases because of the GPS capabilities that all local governments have now. It allows you to see where all the good sites are, which makes land acquisition more cost-efficient than it has been in the past.

Combined with engineering surveys and title searches, it also provides you with a preview of any environmental or legal encumbrance concerns there may be with a piece of land, giving you a much clearer picture of whether or not the land is appropriate for a project. Remember, just because land gets sun, it doesn’t automatically make it the right choice for a project. Finding the right location makes a project more competitive for financing.

Engaging the right partner and acquiring financing early, before all the extra work starts, is another way to make greenfield development easier. Adequate funding can be the difference between a project succeeding and failing. As a bonus, engaging financial partners early in the process allows the partners to share the risks of the project, making it easier to get projects started and completed.

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Though each partner has specific needs, they are all searching for a financing partner that has these four characteristics: • Low cost of capital • Tax equity solution • Easy and flexible to work with • A savvy, experienced team that can navigate the complicated and risky world of solar project financing Early money supports the toughest financing of any project: development capital. The project is much more likely to be a success if developers work with a partner that supports interconnection costs and decommissioning bonds via up-front milestones payments. If the money is there, the chances it will get built rise exponentially.

Developers can lessen their financial burden by working with a company with a low cost of capital that can balance-sheet construction (financing) or do the equipment procurement for the project. It can free up 40% to 50% of the working capital for the developer and allow it to work on more projects at once.

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SOLAR POWER

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LISTEN ON YOUR FAVORITE PODCAST APP OR DIRECTLY FROM ARCHIVES AT WINDPOWERENGINEERING.COM AND SOLARPOWERWORLDONLINE.COM

wind talk Podcasts interview the industry’s biggest newsmakers and allow them to tell their stories.

contractors corner Podcasts feature solar contractors from around the country. See how others are doing business and get ideas to implement into your own.

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INSTALLATION • CONSTRUCTION

SOLAR POWER

Unlike banks, solar/financing companies that have access to low-cost capital just want to achieve their return — anything above and beyond that goes back to the customer.

Experienced solar/financing companies can also perform their own due diligence, which saves money on transaction costs and provides more money to the developer’s profit margin.

Further, finding a company that has tax-equity experience can be the difference between a successful and unsuccessful project. Selecting a company that has in-house tax equity and regular access to tax equity funds saves the developer time and allows it to focus on development work without having to get caught up on the specifics of getting tax-equity funding.

Though greenfield projects are perceived to be the easiest types of deals to get done, lack of financing often ends a project before it begins. Finding a partner that can provide access to early money can alleviate much of that pain and lead to a successful project for everyone involved. SPW

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INSTALLATION • LABOR

SOLAR POWER

FIGHTING LABOR SHORTAGES: STRATEGIES FOR RECRUITING, TRAINING AND RETAINING IN THE SOLAR INDUSTRY MARK VOGEL • PRESIDENT & COO • PETERSEN-DEAN

THE SOLAR POWER INDUSTRY is facing a shortage of skilled labor that we must address. The need for skilled and savvy employees has never been greater, and we as an industry must be fully prepared to meet the challenges. We must spread the word that employment in the solar industry is promising, rewarding and does not require a college degree.

As a national solar installer, Petersen-Dean takes steps to meet the employment demand. Here are some of those tips for success that focus on recruiting, training and retaining.

The importance of retention First and foremost, creating and maintaining a fulfilling workplace experience will certainly help attract and retain workers, whatever their age. We are constantly recruiting through various means (such as online employment services), but many 48

of our new employees come to us via recommendations from our own workers, family and friends. These are the best ambassadors for recruitment and retention. As an added incentive, we give bonuses to our employees whose referrals become new hires, many of whom stay with us for years.

Aim to retain as many capable and skilled employees as possible by providing competitive pay and benefits coupled with a healthy and enjoyable work environment. It is easier to retain employees by making them feel valued and wanted than to find new employees who meet your human resources criteria, especially within a worker-constricted market.

An effective way to achieve that “valued and wanted” goal is to gladly reward employees for a job well done with financial or other means that are measured by factors such as the quality of an employee’s workmanship,

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motivation or leadership skills. Our skilled solar installers can earn up to $50 per hour, and all employees are covered by a full health plan and other benefits such as a 401(k) retirement plan. There’s also plenty of opportunity for overtime work for those employees who want to supplement their regular hours.

However, money is not always necessarily the main factor that motivates workers. According to a study published in Psychology Today, how employees feel about their value in their workplace is often more important than what they earn. These studies show that 83% of respondents said management recognition for a job well done was more fulfilling than any financial rewards or gifts. Drilling down a little deeper, 76% found peer praise “very or extremely motivating” and 88% said that praise from managers was “very or extremely motivating.”

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SOLAR POWER

Our workforce experience underscores the validity of these findings and is a keystone to our employee relations strategy. In an industry known for high employee turnover, 30% of our 3,000 workers have been with us for more than 20 years. If companies want their employees to stay long-term, they need to show them that there is an achievable path to more responsibility and success. Knowing that a job offers significant longevity and rewards is a key factor in attracting and retaining workers, especially younger ones.

The importance of training Proper training is an ongoing process, especially as it relates to safety in solar and roofing installation, that is crucial to both employee and employer success. Before ever starting in the field, our new employees undergo intense safety training covering such basics as proper use of electric equipment as well as ladder and tool safety, safe operation of forklifts, and even how to recognize and treat heat exhaustion. To replicate actual working conditions, much of the training takes place on slanted roof structures with various forms of covering such as tile and composite shingle.

New employees are also introduced to the intricacies and finesse of solar installation by use of a training “wall” where they learn the hands-on workings of a main electric panel and associated wiring, and how to install and disconnect such equipment as an inverter and system monitors. Along with comprehensive on-the-job training, we are confident that all of our workers — whether new or long-time employees — are fully prepared to safely and successfully handle any tasks that the job requires.

To ensure that safety is always top of mind with all our people, we employ 24 engineers who serve as dedicated, full-time safety directors to oversee safety-related operations and hold monthly training seminars in our 30 offices across the country. Along with our workers, seminars are attended by all division and operations managers and general superintendents. Our corporate policy is to provide

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LABOR • INSTALLATION

whatever funding it takes to fulfill our motto that “at the end of the day, we will send every employee home safe.”

Additionally, the roofing and solar industries are constantly monitored by the federal government through the Occupational Safety and Health Administration (OSHA).

Consequently, we work closely with Fed OSHA, and in California, Cal OSHA inspectors who are an integral part of our safety culture and are proud of the fact that we have earned recognitions of our safety records.

Training is just one part of the equation. If companies want their employees to stay long-term, they need to help employees see there is a path to their professional success.

It’s widely known that younger generations entering the workforce are eager for careers that will enable them to grow in the company. Set those expectations early in the hiring process by telling them the different avenues their career could take with the business. We also have a mentor program for veteran employees to work with newer, younger employees and guide them down a path to success.

Installing modern solar energy systems takes a high level of knowledge and skill that, along with safety in the workplace, requires substantial training. A well-trained employee is a valuable employee who is motivated to do his or her best work every day they are on the job. Often, they become project supervisors and leaders and are critical

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INSTALLATION • LABOR

SOLAR POWER

factors in improving workplace safety, productivity and quality control.

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What’s ahead?

Although we work with more than 400 home builders and general contractors in eight states, California is by far our largest solar market. The Golden State took a major step toward achieving its net-zero energy goal by adopting a policy last year that will make solar energy systems standard on virtually every new home built in the state starting in January 2020. That will most likely result in tens of thousands of new homes being equipped with solar systems every year, helping to fuel our own growth fivefold in the next three to five years. As we move forward to keep up with this growing demand, we expect to add another 350 to 400 employees to our current base of 3,000 workers this year.

Looking ahead, we expect other energy-progressive states — Arizona, Colorado, Florida, Hawaii, New Mexico, Nevada, Oregon, Texas, Utah, Virginia and Washington ­— will follow California’s lead, especially as the cost of solar products decreases thanks to better technology and growing demand. Legislation that requires renewables at the local, state, and national levels is creating thousands of new solar jobs. The need for trained employees has never been greater. Given the current labor shortages, when it comes to recruiting, training and retaining, companies will need strategies like these for success. SPW

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12/13/19 10:41 AM

TOP PRODUCTS

SOLAR POWER

2019TOP SOLAR PRODUCTS INNOVATION NEVER SLEEPS in the solar industry, as evident in the swath of new products released in the past year.

While tariffs may keep some products at a higher price, advances across the board to bring hard and soft costs down are making solar systems more affordable and efficient.

The SPW editors traveled to tradeshows and read through every new product announcement from 2019 to choose our top choices for the most innovative products available today or at least coming to market very soon. Let us know how these products work out and what we should be excited for in 2020!

Be sure to check out an even more extensive database of this year's Top Products in our special section online at solarpowerworldonline.com.

Rail-less mounting for any metal rooftop

As seen in Ecolibrium’s MetalX Simplified Racking System It would be convenient if every rooftop in the United States was made of the same material.

Maybe then there would be a universally accepted mounting solution for solar. But in the meantime, at least for metal rooftops, there is Ecolibrium’s MetalX Simplified Racking System.

If installing rail-less mounts isn’t too big of an ask, MetalX is designed to adapt to all metal roof types — standing seam, corrugated, R-panel — across solar markets. The mount is made of only three components: XClamps, preassembled couplings and, of course, the roof mount.

MetalX is compatible with 30- to 50-mm module frames and its couplings promise to cut the number of attachment points required for installation.

MetalX comes with optional accessories, like cable clamps that attach to the XClamps or module frames for easier wire management, a common issue in rail-less mounting options.

Panel racking drops straight into properly aligned mounts; and since installers using MetalX will be working without rails, that means less for them to carry onto rooftops.

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SOLAR POWER

String inverter installations as simple as iPhone setup

As seen in the Fronius Primo GEN24 string inverter Apple is known for simplistic design, from packaging to setup. When you open a new iPhone, the small box is filled with only the essentials, in the order you need them — phone, charger, headphones, manuals. Inverter companies are now working to make unboxing and installation as easy as Apple for solar contractors.

Fronius’s Primo GEN24 string inverter is the company’s first hybrid model, and its smallest.

The sleek, square design features its signature SnapINverter mounting method using a square wallmounted bracket and plug-in wiring.

The company has even simplified the little things in installation — the Primo uses 180° locking screws to shorten drilling time, and the device is packaged with the mounting bracket on top, in order of what must be installed first to last. Once installed, the inverter can be commissioned using an app.

The hardworking GEN24 can keep one outlet alive if the grid goes down during the day without a battery. With a battery added, the GEN24 inverter can supply the whole house with emergency power when the grid goes down, day or night. Installers can give homeowners all those features in a flash thanks to easy installation and setup.

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TOP PRODUCTS

A universal energy storage system takes the guesswork out of solar+storage retrofits As seen in the Humless Universal Energy Management system

Adding storage to a solar project can be complicated. Will the project be AC- or DC-coupled? Can the inverter handle storage functions? Is the battery compatible with the inverter brand? It doesn't have to be this complex — just find an energy storage system that integrates with any manufacturer's panels, inverters and batteries and enables simultaneous AC and DC coupling.

Yeah, right.

Humless made it happen with its Universal Energy Management (UEM) system. First developed for off-grid environments in Africa where developers didn’t have easy ways to ensure system components were compatible, UEM is ideal for solar retrofits in the United States where marrying existing products with evolving power needs is a rising problem. UEM is brand-agnostic, so any inverter can work with any 48-V battery. And UEM's ability to AC- and DC-couple simultaneously provides more energy management options for end users — batteries can be charged by solar panels or bypassed to extend battery life.

Inverter company ABB was looking for a battery to recommend as compatible with its residential inverters when it approached Humless. Rather than pick one battery model, ABB can allow end users to choose whichever batteries they want through the UEM system. This first inverter partnership signals big things for Humless and universal energy storage systems. Installers are looking for tested, single units to quickly get solar-plus-storage retrofits off the ground.

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TOP PRODUCTS

SOLAR POWER

HJT packs more power in a small solar panel punch As seen in REC's Alpha Series

Commercial and utility-scale projects benefit from having more space — more room for larger arrays and more powerful 72-cell solar panels. We're seeing many 72-cell models pushing 425 W, easily. But on residential projects, space constraints still call for 60-cell panels, and installers and end-customers still want those big-number power outputs.

REC Group released a solution with the world's most powerful 60-cell solar panel. Although it only reaches 380 W, that still represents a 20% increase of power over conventional 60-cell panels. The REC Alpha Series continues the company's pioneering "twin panel" design, using 120 half-cut cells, but this time REC turned to heterojunction technology (HJT). HJT combines the best qualities of crystalline silicon with those from amorphous silicon thin-film to produce a high-power hybrid cell. HJT cells are what pushed the 60-cell Alpha module to the highest power ratings in the industry (REC's legacy TwinPeak 60-cell module series using half-cut PERC cells hits 330 W).

REC is very confident in HJT, announcing in August that it would increase its production capacity of the new Alpha series from 600 MW to multiple gigawatts at its Singapore manufacturing facility. The Alpha module reaches 21.7% efficiency and is backed by REC's 25-year product warranty and a 25-year performance warranty that guarantees 92% of initial power at year 25. REC drew a line in the sand by investing in HJT, and other manufacturers are sure to follow suit to stay competitive in the growing residential market.

Virtual reality apps make it easier to service central inverters As seen in SMA's Virtual Service App for central inverters

When weighing the benefits of string vs. central inverters for utilityscale solar projects, string models generally win because of their ease of serviceability. Typically, when central inverters go down, experts must be hired to perform the maintenance. SMA's new Virtual Service App aims to solve this challenge through augmented reality.

Technicians simply open the mobile app, scan the code on the Sunny Central UP inverter and then enter a Virtual Reality portal. Once there, they can hold their device up to the inverter to identify faults and error codes, then view videos and circuit diagrams as well as step-by-step replacement instructions.

Contractors must go through an online training course before they can use the app, but once they've completed it, they're able to perform central inverter maintenance without calling in an outside expert. This service assistance can save money on O&M and cut the project's downtime too.

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TOP PRODUCTS

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Prices now starting at

As seen in the Sunfolding T29 SingleAxis Tracker Picture the actuators on a single-axis solar tracker, and what comes to mind?

A shared driveline, extending between columns of panels or maybe a driver to every row of modules. Gearboxes and motors are the standard, but Sunfolding’s T29 Single-Axis Tracker diverted tracking expectations when it first hit the solar market with AirDrive, a proprietary airbag driver that inflates and deflates to enable tracking.

Now, the T29 has been updated from its previous model. It’s still manufactured using the same fabrication processes, but in this latest iteration, Sunfolding took greater consideration for assembly and shipping. The singleaxis tracker is constructed using a single bolt-type throughout, minimizing the number of components needed for assembly, which cut system weight by 20%, and requires 15% fewer posts for mounting than its previous model.

With the T29, AirDrive is installed on the back of every individual set of racking to give installers greater adjustability for row lengths and undulating topography at worksites.

Using an air-driven actuator in lieu of motors and gearboxes means systems endure less wear and tear. Plus, T29 racking is compatible with any type of ground mount foundation — from ballast to ground screw.

2020 RENEWABLE ENERGY HANDBOOK

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Price Reduction!

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Offer good until December 31, 2019 • Ask for V25995

In anticipation of introducing new videoscope technology in 2020, which will retail starting at $9995, we are now offering our current Hawkeye V2 Videoscopes starting at only $5995… a tremendous value for the scope that has been the industry leader.

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ADVANCED BOLTING TECHNOLOGY

With torque ranges up to 15,000 Nm, the E-RAD

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Quiet – Operates at 75 db reducing noise level

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Fast – Decreased tightening times by up to 300%

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accuracy (+/-2.8%) and repeatability (+/- 2%)

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Accurate – Designed to provide a high degree of

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Light – Unsurpassed power-to-weight ratio

UE TOO

BLU uses a patented gearbox design and the precision of an electric AC Servo motor. These tools deliver smooth continuous torque and are capable of torque and angle sequence. They also feature enhanced traceability with data collection.

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E-RAD BLU 2019-04-01 10:53 AM AM 12/13/19 10:41

WINDPOWER

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CASTROL OPTIGEAR SYNTHETIC CT 320

THE LONGEST TRACK RECORD, LONGEST OIL LIFE AND LONGEST GUARANTEE. • Castrol has over 30 years of experience and knowledge in the wind industry.

• Our Optigear CT 320 gear oil is running on its 10th year without intervention.

• An industry leading guarantee gives you the confidence you’ve chosen the very best.

Discover why leading turbine manufacturers and energy companies opt for Castrol Optigear.

WINDPOWER

For more information go to castrol.com/windenergy or call 1-877-461-1600

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WINDPOWER

MARKET OVERVIEW

2020: A SHIFT IS COMING TO THE U.S. WIND INDUSTRY THIS YEAR for the U.S. wind industry will be one of transition, as spending shifts from installation to operations and maintenance.

But before that, the country is going to install a lot of wind megawatts.

Industry researcher Wood Mackenzie Power & Renewables expects the United States to add 14.6 GW of wind capacity in 2020 — a record-breaking installation amount. The wind industry's strongest year before this was 2012 with 13.1 GW. This 2020 peak comes via the final phasedown of the production tax credit (PTC) in 2021, which has wind developers rushing to complete projects in 2020 to get the full credit amount (if their projects started in 2016). With big installation numbers comes the potential for connection delays and permitting bottlenecks.

“The lack of available logistical resources will begin to cause schedule rearrangements and delays that will grow more apparent during the first and second quarters of 2020,” said Anthony Logan, lead author of the WoodMac report.

In fact, the report assumes 6.6 GW of projects scheduled for 2020 will not reach completion in time and will instead connect to the grid in 2021.

As the PTC disappears, WoodMac forecasts the United States to add 12.3 GW of wind power in 2021 before bottoming out at 5.9 GW in 2024. As wind turbine installations slow, more focus will be spent on maintaining the cumulative 100 GW of wind capacity installed thus far throughout the country.

But there is one thing that could change everything: offshore wind turbines.

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The United States has an offshore wind potential of more than 2,000 GW — nearly double the nation's current electricity use.

With one 30-MW offshore project off the coast of Block Island, Rhode Island, and many more plans proposed, the United States could shift wind installation from land to water in a big way.

Vineyard Wind hoped to own the title of "first offshore wind project in U.S. federal waters," but its 800-MW Vineyard Wind I project off the coast of Martha's Vineyard, Massachusetts, has hit permitting delays. The new frontrunner is utility Dominion Energy, which has received the go-ahead to build the 12-MW Coastal Virginia Offshore Wind (CVOW) project this year. The two-turbine project may be small, but all major development plans have to start somewhere. Dominion Energy has proposed a 2.6-GW offshore wind portfolio off Virginia's coast after successful deployment of the CVOW project.

Renewable energy leader California has also taken notice. A coalition of wind industry leaders launched the group Offshore Wind California last year to promote the responsible and sustainable deployment of offshore wind power in the state's energy system. The group urged California to set a goal of reaching a minimum of 10 GW of offshore wind by 2040. NREL has estimated California's potential for offshore wind at 112 GW. The wind industry will have an interesting 2020 with record-breaking deployment and the beginnings of a shift to offshore wind development. Welcome to a new decade in wind. WPE

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TOP WIND STATS TOP STATES FOR CUMULATIVE WIND CAPACITY THROUGH Q3 2019 • • • • •

Texas (27,036 MW) Iowa (8,957 MW) Oklahoma (8,072 MW) California (5,842 MW) Kansas (5,653)

TOP STATES FOR WIND ENERGY'S SHARE OF STATE ELECTRICITY GENERATION IN 2018 • • • • •

Kansas (36%) Iowa (34%) Oklahoma (32%) North Dakota (26%) South Dakota (24%)

TOP STATES FOR CUMULATIVE INVESTMENT IN WIND ENERGY THROUGH 2018 • • • • •

Texas ($46.5 billion) Iowa ($16.3 billion) California ($14.8 billion) Oklahoma ($14.7 billion) Kansas ($10.5 billion)

TOP STATES FOR APPROXIMATE TOTAL WIND JOBS • • • • •

Texas (26,000 jobs) Iowa (10,000 jobs) Colorado (8,000 jobs) Illinois (8,000 jobs) Oklahoma (8,000 jobs)

TOP STATES FOR WIND CAPACITY UNDER CONSTRUCTION • • • • •

Texas (6,261 MW) Wyoming (3,753 MW) New Mexico (1,447 MW) Iowa (1,122 MW) Oklahoma (1,017 MW)

TOP STATES FOR OFFSHORE WIND PROJECT PIPELINES AS OF 2018 • • • • •

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Massachusetts New Jersey North Carolina Rhode Island Virginia

WINDPOWER ENGINEERING & DEVELOPMENT • 2020 RENEWABLE ENERGY HANDBOOK

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There’s a lot to consider when selecting a state in which to do wind business.

Here’s an easy way to look at which states are excelling in the industry and in what ways.

Sources: Information from AWEA, DOE

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TECHNOLOGY • BOLTING

WINDPOWER

HOW GALLED FASTENERS MAY AFFECT WIND TURBINE O&M PATRIK LUNDSTRÖM TÖRNQUIST • MANAGING DIRECTOR • BUMAX ANDERS SÖDERMAN • TECHNICAL DIRECTOR • BUMAX

GALLING IS A FORM OF WEAR that is caused by metal surfaces in gliding contact with one other, such as the many bolts and fasteners holding rotor blades together in wind turbines. With potentially disastrous and costly effects resulting from galled fasteners seizing or even subject to a fatigue breakage, the wind energy industry players are advised to counter this threat.

Standard stainless steel bolts and fasteners have a tendency to gall under certain conditions because of their specific properties. Thread galling can occur with standard fasteners when pressure and friction cause the bolt threads to seize to the threads of a nut or a tapped hole.

Severe galling, known as “cold welding,” can also cause the two surfaces to fuse together. This makes the joint impossible to remove without cutting the bolt or splitting the nut. The consequences and implications of galling should never be underestimated.

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A galled fastener may be unable to achieve the necessary pre-load and, particularly, in case of dynamic loading. This jeopardizes the entire purpose for using fasteners (i.e. to securely fasten two surfaces together).

What’s more is this risk may involve hundreds of stainless steel fasteners, such as with rotor blades.

In the worst-case scenario, the fatigue breakage of critical fasteners can have serious safety implications that might result in accident or injury. Galled fasteners are also much more susceptible to corrosion, which can ultimately result in breakages and high maintenance costs.

Catastrophic failures Galling is an issue in many segments and applications, wherever stainless steel fasteners are used. For example, in the wind energy industry, there is a risk of catastrophic failures if the thread galls before sufficient torque has been obtained. This covers most if not all machines and devices with moving parts.

Wind-turbine manufacturers typically use a premium fastener like the BUMAX 88 for rotor blade bolts because it has a high molybdenum content that makes the joints

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CAREER

WITH

BUILD YOUR

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INTERNSHIPS | FIELD | CORPORATE CHECK OUT OPEN POSITIONS AT WANZEK.COM/CAREERS

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TECHNOLOGY • BOLTING

extra durable, reliable and corrosion-resistant. In extreme cases, galling can lead to the fastener breaking and failure of the application. The risk is highest for applications that are exposed to dynamic loads.

However, galling can be overcome even in the most challenging of applications — particularly by selecting premium quality stainless steel fasteners.

Prevention It is important to consider how galling can be avoided from the outset when engineering a fastener application to decrease the chance of repairs and maintenance costs. To minimize galling and its negative consequences, it is essential to be aware of the concept of galling and ensure that only premium stainless steel fasteners are used in critical applications.

Premium fasteners may look similar to standard stainless steel fasteners, but their superior material properties can make a significant O&M difference. Premium stainless steel fasteners also typically offer other properties that are essential in many critical fastener applications — including corrosion-resistance and high tensile strength.

Using premium fasteners that are at a lower risk of galling offers the following benefits: • Less maintenance, stoppages and other production disturbances. Most machines used in production are designed to clock up thousands of hours of “work” with very little downtime. Any downtime can be very costly in terms of repairs and lost operational revenues. A well-known German construction company of offshore wind turbines used to weld the tower construction, but experienced costly and complicated maintenance work when service ships collides into the construction at heavy sea. Changing from welded joints to BUMAX stud fasteners made it much easier to replace damaged parts and has thereby lowered the maintenance cost.

• Increased safety and security. If a fastener malfunctions or breaks, the result can be dangerous and even disastrous, depending on the application.

• Increased cost-effectiveness. Using the best fasteners from the very start can save a lot of money down the line.

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The extra cost for premium fasteners pales in comparison to repair and replacement costs. Besides choosing the correct fasteners, there are other preventative measures to take: 1. Select the correct material. Selecting the correct material for your specific application is extremely important as certain types of stainless steel are more prone to galling due to their atomic structure. In particular, strain-hardened stainless steels that have been cold formed provide excellent galling resistance due to their improved strength and reduced ductility.

2. Choose fasteners with a perfect fit. As galling is common between metal surfaces that are in sliding contact with each other, premium fasteners that are designed to perfectly fit together can significantly reduce the risk of galling as they minimize movement and friction. Here, high-quality threads with less surface deviations that can rub together and lead to galling issues are particularly essential.

3. Lubrication matters. Lubrication is an important way to reduce galling by allowing the two materials to slide past each other without causing friction. Some leading premium fastener manufacturers use custom-made wax to ensure an optimal friction coefficient. Anti-seizing and anti-galling lubricants can also help reduce galling.

4. Discard damaged fasteners. A bolt with dented or damaged threads has a significantly increased chance of galling. Check all fasteners for damage that may have occurred during shipping. Dirty bolts with debris in the threads can also greatly increase the risk of galling — so make sure you only use clean bolts.

5. Careful installation is key. As most stainless steel is more sensitive to high temperatures, tightening bolts more slowly can reduce friction and heat that can cause galling. This may involve avoiding the use of power tools that can cause excessive friction and heat.

Calculations should be made for particular applications to determine the kind of tools that can be used.

You must ask yourself: How valuable are your wind energy assets? Is it worth gambling on cheaper, gallingprone fasteners and bolts rather than premium stainless steel fasteners that are specifically developed to minimize galling?

Wind energy industry executives must be aware of the potentially disastrous implications of fasteners failing due to galling, and do their utmost to prevent this from happening.

This cannot be left to chance. WPE

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WINDPOWER

CABLES • TECHNOLOGY

AN INTERVIEW WITH NICK KORTH • PRODUCT MARKETING MANAGER OF ENERGIES • HELLERMANNTYTON

HOW CABLE REQUIREMENTS ARE EVOLVING ON WIND PROJECTS

HELLERMANNTYTON manufactures cable management products and identification systems for a number of industries, including solar and wind. The company’s engineered solutions are designed and constructed to meet the strictest quality standards and last in the harshest conditions — from desert solar environments to salt-sprayed offshore wind farms. HellermannTyton formed in 1969 in Wisconsin and today operates in 39 countries. We talked with Nick Korth, product marketing manager of energies, to get some insight into how cable management is evolving on wind projects.

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What kind of cable management is necessary on onshore and offshore wind projects?

There are many different applications when it comes to standard wind turbines. Each application uses specific cables, leading to a wide variety of wire management needs. High voltage, control and data cabling all have different routing requirements. For example, the nacelle contains moving and rotating parts with the pitch control and yaw system. These cables are often high voltage and large, so ensuring

they are secure is important because repairs can be expensive and time consuming.

The gearbox and drivetrain can be another demanding area for cable management solutions. It is critical to specify the right product mix — such as large, 250-lb cable ties with heavy duty mounts — as well as work with a company that has intimate market knowledge and material expertise.

In the tower, the cables remain mostly stationary. Some cables, such as tower lighting cables and weather monitoring systems at the top of the nacelle area, are exposed to a wide variety of harsh elements.

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TECHNOLOGY • CABLES

Be More Limitless.

Whether you need a custom solution or one of our standard products, Deublin’s proven engineering expertise and market experience will help propel your most powerful ideas.

Visit WWW.DEUBLIN.COM to select and order your optimal solution today!

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WINDPOWER

What environmental conditions have to be considered for wire management on wind projects that maybe aren't as much of a concern on ground-level applications?

At the top of the turbine, wire management can experience high wind loads and challenging weather conditions such as ice accumulation.

Careful attention should be given to the same conditions at ground level. Heat, UV and cold are all severe environmental factors that can degrade wire management components. For example, cold and dry climates can make plastic components brittle. By choosing the right material and manufacturer, a specifying engineer can choose a material that is enhanced with modifiers that provides a longer performance life.

Offshore installations can experience more moisture, leading to a variety of issues.

Moisture and salt can degrade materials like metal. Choosing high quality metal products, or plastic for that matter, to avoid issues with dissimilar metals or premature degradation is important. Other considerations include lubricants, chemicals and oils. With long-term exposure, these liquids can severely impact metal and plastic, so knowing the material and performance characteristics of these wire management components is critical.

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WINDPOWER

CABLES • TECHNOLOGY

What future wind turbine advances is HellermannTyton keeping an eye on?

As with all the industries we supply products to, increasing efficiency for installers as well as the O&M market is critical.

We want to make sure all of our products are easy to use while providing the same high-quality performance that HellermannTyton is known for. There has been increased demand for turbine monitoring in several areas, such as the blades, bearing and generator production and tower movement.

With further reductions in weight, active load controls are demanding more monitoring points on the turbine to increase safety and stability during operation. The cabling of the monitoring points is one of our focus areas.

Another point of emphasis is fewer mounting attachments, such as holes or bolts to manage cables. Traditional routing methods are now giving way to magnetic and adhesive solutions for this market. WPE

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12/13/19 2:10 PM

TECHNOLOGY • BLADE COMPOSITES

WINDPOWER

HOW COMPOSITE MATERIALS INFLUENCE BLADE SIZES AND FUNCTION AN INTERVIEW WITH STEPHEN NOLET • PE, SENIOR DIRECTOR OF INNOVATION AND TECHNOLOGY • TPI COMPOSITES

TPI COMPOSITES is a global, independent manufacturer of composite wind blades for the onshore and offshore wind market. The company is headquartered in Arizona and operates factories in the United States, China, Mexico, Turkey and India. TPI has worked with a number of major players in the industry and has a specific area of insight into the future of wind manufacturing. We talked with Stephen Nolet, PE, senior director of innovation and technology at TPI Composites, about the latest developments in wind blades.

What are today's wind turbine blades typically made of?

All utility-scale wind turbine blades are manufactured using one form or another of reinforced polymer composites. The most widely use material system is a combination of E-glass (or boron-free E-CR glass) and liquid epoxy that is cured in shell-molds that define the aerodynamic surface of the blade. However, a large number of blades have also been 66

put into service using other liquid resins including polyester and vinyl-ester. But in fact, many blades by the largest OEMs have also incorporated carbon fiber for the spar caps that make up the “backbone” (bending element) of the blade.

Carbon provides almost five-times the axial stiffness per kilogram of weight compared with fiberglass and can enable longer blades without increased rotor loads on the drive train and generator.

How have the different composites evolved over time?

As the locations with wind rich resources are developed, we see movement toward regions with lower wind speeds and lower net rotor energy (i.e., < 250 W/m2). This has driven rotor designs that are larger and larger for a given generator nameplate capacity. As blade length increases, we see more use of carbon fiber for spar caps. Given the cost of carbon fiber and the cost of conversion to textiles for resin infusion, a new trend has evolved in the use of “pultruded” plates

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BLADE COMPOSITES • TECHNOLOGY

that are laminated to convert the lower cost carbon roving form directly into unidirectional spar caps where translation of properties yields the highest specific stiffness at lowest possible cost. This is innovative and very effective.

Other emerging trends include the investigation of different resins (to replace epoxy and polyester). The emergence of 2K urethanes can take advantage of room temperature (or near room temperature) curing combined with ultra-low mixed viscosities to reduce cycle time and reduce tooling cost. The inherent “toughness” (i.e., high strain to failure) of the urethane resins may yield higher fatigue strength and improve long term blade reliability.

There's still much work to do here. The development of liquid molding resins (such as the Arkema Elium resin) that can be infused in reinforcements and cured at room temperature to yield a high molecular weight thermoplastic acrylic will pave the way for blade disposal solutions where the blade can be ground up and compounded with virgin thermoplastic materials to create long fiber reinforced pellets for injection molding of a whole array of consumer and automotive products.

What are the benefits of composite materials?

The primary benefits of any material selection has to be measured in terms of performance and cost. The use of glass and carbon fiber reinforced composite materials provide both advantages over traditional engineering materials (i.e., steel and aluminum). With similar specific stiffness and significantly better specific strength, glass fiber composites result in lighter weight blades compared to metallic designs. The rich palette of materials and ever increasing properties of both glass and carbon fiber has enabled a continued trend of blade length extension to achiever ever higher turbine capacity factors.

Indeed, there are many markets and applications where composite materials do not compete well with engineering metals because of significant differences in the fundamental material and labor costs. However, with rotor blades, composite materials can leverage their extreme scale to neutralize labor content and their inherent advantage for lower cost of tooling (i.e., mold cost) compared to progress stamping dies or forming tools (for hydroforming of aluminum, for example) required to build an equivalent metal

windpowerengineering.com

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design. While a composite wind turbine blade is molded in and assembled from as little as a dozen subassemblies, an equivalent metallic design would require as much as an order of magnitude higher number of parts with the requisite set of jigs and assembly fixtures required to rivet or weld the blade into a unitary construction. For extremely high volumes, this might favor metallic design in terms of bill of materials and labor, but volumes of any given blade design has been limited in the extreme to maybe 5,000 to 15,000 units and the design is replaced by new (longer) products and new planforms. The cost of re-tooling metal designs would be cost-prohibitive.

How are composites influencing new wind turbine sizes?

Composite materials enable the use of higher specific property (i.e., strength/density and stiffness/density) materials to reduce blade weight even as rotor diameters continue to push higher and higher. The mechanisms of damage accumulation (i.e., fatigue) are far slower in bonded composite assemblies compared to equivalent riveted aluminum construction. The combination of higher reliability with longer inspection intervals favor composite designs and encourage this trend of rotor growth for both on-shore and off-shore installation. Growing capacity factors drive down LCOE, keeping wind in its position as the lower cost form of electrical energy generation. WPE

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TECHNOLOGY • FILTERS

WINDPOWER

TIPS FOR CHOOSING A WIND TURBINE FILTER COMPILED FROM INFORMATION IN THE WPE ARCHIVES

WIND TURBINE gears and bearings ride on a film of oil only a few microns thick. This might seem insignificant, but quality gear oil and fine filtration are imperative to avoid unnecessary wear and equipment downtime.

Filter elements are typically rated based on their ability to remove contaminants of specific targeted sizes from a fluid under set operating conditions. Enough contaminant particles, measuring only 1-μm in size and invisible to the human eye, can take down a 20-ton gearbox.

That's why it's important to choose a filter that accommodates the needs of the system and filters the targeted particles of concern.

For example, water-removal filters and fine micron-rated filters are best used for hydraulic and gearbox fluids. On heavier gear oils, flow rate, pore size and dirt-holding capacity are the key features to look for.

On a kidney loop (offline) filtration system, ensure the flow rate is right for the sump size. The system should not take more than 10% of the total sump volume per minute.

Product managers at Des-Case, a manufacturer of contamination control products for industrial lubricants, stated that it costs, on average, 10-times as much to remove contamination from a system than it does to exclude the contamination in the first place. To improve reliability and keep particles from entering a system in the first place, Des-Case recommends a high-quality desiccant breather.

A desiccant breather replaces the standard dust cap or OEM breather cap on equipment and provides better filtration and protection against even the smallest particulates that can destroy the effectiveness of turbine components. As air is drawn into equipment through the breather, the layered desiccant filter elements remove particulate. Desiccant breathers are also very effective at removing existing headspace moisture.

When selecting desiccant breathers, look for features such as a high flow rate (especially for hydraulics), check valves and a large volume of filter media and silica gel to extend the breather life.

In the wind industry, maintenance tasks are a challenge. That's why it is important to choose components that last. Compare dirt and water-holding capacities of different filter elements, as well as their efficiencies. On average, appropriately sized breathers and filter elements should last nine months or longer when in operation.

A better filter choice means more reliability, greater longevity and less worry for wind turbine operators. WPE 68

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REAL SOLUTIONS,

REAL SAVINGS!

Rising repair costs and unpredictable turbine downtime are symptoms of a maintenance program that could be more reactive than proactive. HYDAC can help you determine the true costs of system failure and implement a solution to steady maintenance costs and avoid unplanned outages. Our Wind Field Sales and Service Team is ready to meet any and all challenges, from new designs and solutions to upgrades and retrofits.

HYDAC is your one stop solution!

• NF Filter Kit – Can replace an existing non-HYDAC filter housing in a GE 1.X turbine without disturbing the lubrication pump, motor, or hoses. This kit fits through the nacelle hatch without the need of an external crane.

• GW Sensor – Installed in the filter housing for more precise measurement, it sends a signal if the element is experiencing a sudden influx of contaminant.

• MCS Sensor – A plug-and-play sensor, with multiple vibration measurement unit capabilities, allows for the monitoring of metallic contamination to determine if vibration is due to normal environmental variations or a potential gearbox issue.

• Filter Cart OF5HD-HV – Designed to be lifted through the nacelle hatch, this dual filtration unit can be used to remove both water and particulate contamination or for staged particulate contamination removal.

• Split Housing Uptower Cooler (UTC Series) – Eliminates the need for a costly external crane, saving time and money.

• HYROFLEX Cable Clamps – Part of a system of various mounting supports for securing power cables in wind turbines.

Two styles available, half moon and star.

GW Sensor

MCS Sensor

NF Filter Kit

OF5HD-HV Filter Cart

Clamping Solutions

Split Housing Uptower Cooler

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www.HYDAC-NA.com | www.HYDAC.com

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TECHNOLOGY • LUBRICANTS

WINDPOWER

A NEW WAY TO ASSESS OIL QUALITY IN WIND-TURBINE GEARBOXES JOE HEDGES • PRESIDENT • VOELKER SENSORS

IT IS NO SURPRISE that gearbox failures have been linked to a lack of lubrication due to oil wear and contamination.

Regular oil changes would seem to be the solution.

However, changing oil in land-based wind turbines, or worse, swapping out their failed gearboxes, presents serious challenges due to the height of the turbines and their often remote locations. Offshore installations make for even greater hardship.

Oil changes at predetermined intervals are less than ideal because they are likely to result in the performance of expensive and time-consuming work more often than necessary and well before it is needed. Worse yet, they could result in oil changes occurring after damage to the gearbox has already begun.

These shortcomings make monitoring gearbox oil for contamination and oil wear paramount for the longevity and cost-effective maintenance of wind turbines. Maintenance teams have responded to the need to monitor several ways.

One calls for laboratory analysis while another proposes a continuous in-line solution: • The laboratory solution of “sample and analyze” can provide useful information about the oil and the health of the gearbox. However, the technique is limited to discrete data points that correspond to each sample taken from the equipment. The problem is that oil does not always wear in a linear fashion, so events that cause damage to a gearbox can occur between

Each element includes the Pauling Scale for electronegativity, a measure useful for monitoring oil wear.

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•

sample points. Another disadvantage is the time and cost of pulling samples at remote locations, and from equipment as tall as 300 ft above the ground.

Continuous real-time monitoring of the right set of parameters provides a trend of oil condition and supports a predictive approach to gearbox maintenance.

Parameters of importance are acidity and oxidation, moisture contamination and wear metal contamination.

An innovative monitoring method uses a sensor capable of measuring oil polarity and hence oil wear. Polarity is a reliable indicator of both the oxidation and acidity of the oil.

The patented, proprietary sensor (developed by Voelker Sensors Inc. or VSI) also measures moisture content and the conductivity of the oil — which provides an indication of wear metal contamination.

Polarity, moisture, conductivity and temperature. The essential oil factors — polarity, moisture, conductivity, and temperature — can tell a lot about a gearbox lubricant and better guide its maintenance.

The polarity of oil is a measure of the average difference in electronegativity of the atoms in the chemical bonds of the oil molecule. Each atom has an electronegativity number (shown in the Periodic Table to the left). When the difference between the electronegativity of two atoms in a chemical bond is greater than 0.7, that bond is considered polar.

Fresh gear oil is primarily comprised of carboncarbon bonds. Because carbon atoms have the same electronegativity number, the electronegativity difference between the atoms in the bond is zero and the bond is considered non-polar.

As oil wears, the carbon bonds of the base stock break, and oxygen frequently replaces the cast-off carbon. The electronegativity of carbon is 2.55, whereas for oxygen it is 3.44. The difference between them is 0.89, meaning that carbon-oxygen bonds are substantially more polar than the non-polar, carbon-carbon bonds they replace. As the oil stock breaks down, more of the carbon-carbon bonds are replaced by carbon-oxygen bonds, gradually increasing the oil’s overall polarity.

The VSI sensor measures these small changes in polarity, providing a very sensitive oil wear detector.

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WINDPOWER

LUBRICANTS • TECHNOLOGY

Moisture in oil tends to equilibrate with the moisture in the air surrounding a gearbox. A higher moisture content can age oil, create oxidation on metal components in the equipment, and degrade the lubricating ability of the oil.

A conductivity increase indicates conductive contamination such as that from metals in the oil.

Temperature provides information about how hard the monitored equipment is working.

An advanced sensor for continuous monitoring.

The VSI sensor has been in use in wind turbines since 2013. The Water and TAN graph below is typical and is from an actual VSI installation. The data set covers a period of about five months. The moisture content of the oil shows an increase that is probably due to the relative humidity of the air changing from colder winter months to warmer summer months. The acidity of the oil is also seen increasing as the oil wears.

Imagine if the oil were only sampled on February 3 (TAN 0.60) and again three months later (TAN 0.59).

One would reasonably conclude that the oil had not aged. However, if instead samples were taken on February 3 (TAN 0.60) and July 1 (TAN 0.65), a significant increase in acidity would be noted, but the perceived rate of aging (approximately 1.5% increase in TAN per month) would be significantly understated, leading to a dangerous overestimate of remaining useful life.

The plot of the continuously monitored oil shows that in fact, it failed to age appreciably for the first three months but then began to age rapidly (TAN increasing at a rate of about 5% per month). Due to the non-linear aging of the oil (which is typical), the oil in the later stages of this study was aging at greater than three times the rate that the sample and test approach would have suggested.

The VSI

Final thoughts sensor Monitoring oil installed in the oil stream condition is on the exit essential to the side of a wind maintenance of turbine’s oil high-value and filter. mission-critical equipment. The sample-andanalysis technique provides a wealth of information.

However, the challenges of sampling and testing oil from remote, difficult-to-access equipment and the limited insight afforded into real-time oil condition points to the need for a better solution.

Continuous monitoring of wind-turbine gearbox oil has been shown to be an effective way to track and predict oil wear, and to prevent costly equipment failures. WPE

•

•

Tensioning equipment is customized for any bolt configuration or clearance Our customized equipment can be modified or repaired in the field, reducing downtime

• •

•

Certified pump guages are recalibrated with each foundation Professional reports routinely provided for each foundation tensioned Free bolt cap installation with tensioning service

The orange line plots the water content in the oil of a wind-turbine gearbox from February to July, on the left scale in parts per million.

The blue plot tracks the Total Acid Number (TAN) on the right scale.

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TECHNOLOGY • SLIP RINGS

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SLIP RINGS MAY HOLD ONE KEY TO REDUCING WIND O&M COSTS GEORGE FINLEY • WIND SEGMENT MANAGER - ELECTRICAL CARBON • MORGAN ADVANCED MATERIALS

AT PRESENT, the U.S. has around 58,000 wind turbines, generating a total rated capacity of 91 GW, but the DOE projects that this will increase to over 400 GW by 2050. With this huge increase in power generated by wind, in turn the number of people that rely on this source of energy will also go up — making it integral that downtime, maintenance and operating costs are kept to a minimum.

In with the new In addition to the sourcing of electricity, the maintenance practices of wind turbines are also undergoing a shift. In years gone by, maintenance engineers have often taken a reactive approach, dealing with problems and failures as they arise.

Increasingly though, operators are realizing the severe cost implications of responsive repair methods and are looking to a more preventative approach.

Despite progress in automated diagnostic solutions, sometimes there is no substitute for experienced engineers and technicians that are able to spot the tell-tale signs of turbine failure. One such example lies within the mechanics of the turbine’s slip ring and brush system.

The ring of power Slip rings collect rotor current and send it to the grid. They are often made from solid metals and used in conjunction with carbon brushes, usually made from graphite combined with metals such as copper or silver. The slip ring rotates with the turbine generaetor rotor. The electrical current produced by the rotor is conducted through the rotating slip ring to carbon brushes, held in optimum position by static brush holders with springs which allow the brushes to move and stay in contact with the rotating slip ring.

Gone in a flash It is integral that brushes are held in place with good stability, as instability, known as friction chatter, can occur.

This causes a loss of contact between the brush and slip ring interface that can lead to arcing and damage. Even worse, friction

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chatter can cause a complete flashover, which results in high-voltage electric short circuits that can destroy slip rings, holders and other components in the generator brush box.

This damage can lead to costly downtime and repairs.

Similarly, the instability of brushes leads to excessive brush and slip ring wear, which can produce conductive dust. This dust can cause current to track and flow in places where it is not desired, again increasing the risk of flashover. Brush materials and brush holders are also a contributing factor to failure.

With brush materials and the performance of each differing greatly, poor quality or mismatched brush materials can wear quickly and dust heavily.

Into the groove Brush holders play a large role in eradicating costly downtime in the sense that they provide a stability for the brushes and make a difference in performance and wear rates.

When brush holders aren’t adjusted to the right height, grooving on the slip ring can occur. Grooving is where brushes lose contact with the slip ring, producing arcing, which damages the slip ring in a similar way to how grooves are cut during the electrical discharge machining process.

This loss of contact and arcing can also destroy expensive “Wet A” cards, which can cost as much as a slip ring assembly. The Wet A card is a circuit board in the control system that can be overloaded by current and destroyed when ground currents are not properly shunted through the brush to the ground ring interface.

Loss of contact on the ground ring and the associated arcing can expose the circuit board to the excessive current that overloads the circuits and thus destroys the card.

Bronze is the new gold Slip rings have typically been made from affordable steel.

However, bronze is a much more efficient metal for some applications, reducing failure rates and the time technicians spend in the turbine.

Morgan’s Electrical Carbon is finding greatly improved brush life by using bronze slip rings in tandem with its grade M50BR brush material, which can reduce the frequency of maintenance within the turbine and prevent failures.

While the initial outlay for bronze is higher, its ability to prolong the use of brushes makes it a worthwhile investment.

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RELIABLE SOLUTIONS FOR WIND TURBINE MANUFACTURERS AND OPERATORS.

WHEN HIGH RELIABILITY POWER AND DATA TRANSMISSION IS REQUIRED, MOOG HAS THE SOLUTIONS. Moog has developed direct replacement pitch control slip rings for today’s wind turbines.

The slip ring provides reliable transmission of power and data signals from the nacelle to the control system for the rotary blades. The ring/brush contacts produces minimal wear debris for over 100 million revolutions with field demonstrated performance.

Pitch Control Slip Ring Advantages:

Moog’s proven fiber brush technology has become synonymous with high performance slip rings around the world. With over 50 years of experience and more than 10,000 slip ring designs, our engineers work together with your design team to find a solution that is right for you.

• Wide operating temperature range

• High reliability • Minimal wear debris generated • No lubrication required • Reliable data transfer • Lower life-cycle cost

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TECHNOLOGY • SLIP RINGS

In contrast to steel, bronze runs cooler and decreases the amount of heat-related damage to the carbon brushes. This is because bronze’s thermal characteristics are better for heat dissipation and with the proper brush material, its ability to form a better patina reduces friction. This leads to longer brush life with less risk of potentially dangerous dusting.

To prevent dusting, engineers should also look to slip rings with specialized paint coatings. These prevent brush dust collecting and sticking to the slip ring, reducing the undesirable tracking of current.

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Replacing steel with bronze When looking to replace slip rings with bronze, engineers should first find a supplier that has invested R&D into its insulation materials. Improved insulation materials will have a higher dielectric strength, be more resistant to higher temperatures and have “non-stick” properties to keep conductive dust from collecting and current from flowing where it is likely to cause damage or destruction.

Second, the width of the slip ring is also important when looking to decrease temperatures. To counter this, Morgan has developed a bronze slip ring with a 20% increased width for additional thermal mass and added cooling holes for better heat transfer.

Spotting the tell-tale signs As much as new technologies can do for the maintenance and servicing of wind turbines, there is no substitution for experienced design and knowing how materials perform together. As well as matching the bronze slip rings to the appropriate brush materials, and then correctly adjusting the brush holders, there are also a whole host of other areas where Morgan has improved slip ring design.

This includes the aforementioned paint coatings, increased ring width and cooling holes, but also stud diameters and stud balance should also be considered. WPE

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WINDPOWER

CONSTRUCTION • INSTALLATION

DEVELOPERS ARE TESTING UTILITYSCALE WIND IN MICROGRID MARKETS BILLY LUDT • ASSISTANT EDITOR • WINDPOWER ENGINEERING & DEVELOPMENT

MICROGRIDS FIT multiple classifications of energy sources independent from or in addition to grid-tied energy providers. They are independent electrical grids that can either run on energy generated from nongrid-tied sources like wind turbines, solar panels or diesel generators; or microgrids act as a backup power solution in the event of a grid outage. Microgrids are often used in resiliency applications, where electrical grid outages can otherwise leave an offtaker vulnerable, physically or financially.

For grid-tied, developed communities (those with established roadways and highway systems), municipalities can have regulations for structure heights and may require a turbine be built a specified distance from residences. This was the case for state utility Ameren Illinois that constructed a microgrid on a property adjacent to the University of Illinois in Champaign, Illinois. The company installed a 167-ft, 100-kW turbine in the microgrid project, meeting Champaign’s mandate requiring the structure to not be built taller than 175 ft or within 1,000 ft of a residential customer.

Ameren Illinois’s microgrid, or Technology Application Center, at the University of Illinois, was constructed to determine how different distributed energy resources would affect the electric distribution system. The microgrid is composed of a wind turbine, photovoltaic solar and a diesel generator, and integrated with Champaign’s electrical grid.

For wind to be a viable power source for a microgrid, an energy storage component is recommended. windpowerengineering.com

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“Wind doesn’t blow all the time — it’s intermittent. So, problems can develop because the wind changes speed and direction all the time,” said Rod Hilburn, manager of the Technology Application Center (TAC) with Ameren Illinois. “It’s not constant. You’re not burning coal and you don’t have hydro that’s keeping the turbine spinning at a nice constant pace. Those are some things that we’re trying to research. “ Installing a megawatts-large wind project as a microgrid would require a companion battery to store excess energy generation.

The Ameren microgrid is considered a utility project, but its wind generation is far less than a multiple-turbine wind farm. Scaling storage to that size of energy generation can prove difficult but will be necessary to make wind more viable in microgrid applications.

From an economic standpoint, the cost-benefit of a microgrid is on a case-bycase basis, but reliability can be a significant decider, Hilburn said.

“If you have customers who have processing inside their plants that require extreme levels of reliability…you end up having a mess that the costs of cleaning up may outweigh the premium cost you have in order to put the microgrid into place,” he said.

Ameren Illinois’s utility-scale microgrid was constructed to determine how different distributed energy resources would affect the electric distribution system.

Many existing microgrids are deployed in underdeveloped regions that don’t have access to an established electrical grid or road infrastructure. Diesel generators and smaller wind turbines have been a standard for these off-grid applications.

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INSTALLATION â&#x20AC;˘ CONSTRUCTION

â&#x20AC;&#x153;Wind turbines have gotten larger, multi-megawatt-sized, and thereâ&#x20AC;&#x2122;s actually a void in the market between the great big and the very small wind turbines,â&#x20AC;? said Matt Carter, president and CEO of Carter Wind Energy. â&#x20AC;&#x153;This is exactly where we see microgrids and the need for medium-sized turbines.

Thatâ&#x20AC;&#x2122;s where the industry is. Thatâ&#x20AC;&#x2122;s why they overlook this microgrid market because theyâ&#x20AC;&#x2122;re focused on large wind farms or what I call developed economies and developed infrastructure.â&#x20AC;?

A limiting factor for utility-scale wind projects trying to break into remote communities is accessibility.

Hauling the components of a utilityscale turbine to an undeveloped region

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poses limitations in infrastructure critical to construction. The cement machinery required to pour a foundation and the cranes for installing turbines cannot always access these regions easily.

And a megawatts-large wind farm could produce more energy than needed in that setting. â&#x20AC;&#x153;Think about if you ever had any maintenance that you have to do on the wind turbine. You have to bring out another crane to do that work in the Lower 48 [states] or in developed regions where thereâ&#x20AC;&#x2122;s roads and all this infrastructure,â&#x20AC;? Carter said.

Carter Wind Energyâ&#x20AC;&#x2122;s product solution for this accessibility issue is a self-erecting wind turbine that doesnâ&#x20AC;&#x2122;t require a crane for installation and uses

a guide tower to reduce the cement required for a foundation. Diesel generators are popularly used in remote microgrid applications, and a case study by Northern Power claims wind power costs a third of diesel to operate. In addition, turbines occupy less space than an average power plant. â&#x20AC;&#x153;It doesnâ&#x20AC;&#x2122;t matter what the cost is, many of these microgrids that are operating and using diesel â&#x20AC;&#x201D; expensive diesel â&#x20AC;&#x201D; they canâ&#x20AC;&#x2122;t use wind because thereâ&#x20AC;&#x2122;s just not the equipment there to install it and maintain it,â&#x20AC;? Carter said. WPE

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OPERATIONS & MAINTENANCE • INSTALLATION

EXTENDING MAIN-SHAFT BEARING LIFE IN WIND TURBINES DAVID DE GARAVILLA • APPLICATION ENGINEERING TEAM LEADER • SKF DR. XIAOBO ZHOU • PROGRAM MANAGER • SKF

THE RENEWABLE ENERGY SECTOR is being forced to reduce the levelized cost of electricity (LCOE). The wind energy industry is striving to match or exceed the LCOE of traditional energy sources. Due to the cost of the equipment combined with the lower relative operations and maintenance costs compared to traditional energy, the driving factors in reducing the LCOE in wind are the costs of the equipment and uptime.

Uptime in wind turbines is critical to the future of the energy source. In the past Common main-shaft spherical roller years, SKF scientists and research engineers bearing outer ring damage. conducted systematic investigation and SKF NoWear is a wear-resistant, metal-containing verification tests on key parameters, which may hydrogenated amorphous carbon coating that is applied have strong contribution to the main-shaft bearing performance. to the rolling elements of spherical roller main-shaft According to the investigation, following parameters have bearings. A physical vapor deposition process applies been identified: the wear-resistant, metal-doped, diamond-like-carbon • Lubrication starvation can be a direct cause of bearing coating. Thickness of the coating ranges from 0.6 to 6 failure, which will result in fast wear and surface distress µm, depending on the size and geometry of the bearing. (micropitting). This can lead to edge load on the wear The nano-indentation hardness of the coating is 12 GPa grooves resulting to so-called spall bands in circumferential (~1,200 HV). direction of the bearing raceways.

NoWear coated bearing surfaces retain the • Lubricant starvation is the result of the lack of grease in the toughness of the underlying material while adopting contact and oil depletion in the grease. the hardness, improved friction properties and wear• There are many parameters which have been identified to resistance of the coating. The dry sliding coefficient accelerate lubricant starvation, such as incorrect selection of NoWear against a steel counterpart is less than 0.2 of lubricating greases, improper re-lubrication method, while that of bearing steel is 0.6 – 1.0. As such, NoWear high friction, high sliding to rolling ratio, low lubrication film coated bearings can operate reliably even where thickness, etc. adequate surface separation cannot be achieved.

NoWear acts as a protective layer and may reduce To reduce the risk of lubrication starvation, SKF NoWear the need for Extreme Pressure (EP) additives in the surface coating has been selected and verified, which can not lubricant. This is beneficial in wind-turbine main-shaft only increase the wear resistance on the raceway surfaces, but applications, since EP additives should be avoided if also reduce the friction and therefore prolong the grease life. possible as they can contribute to the generation of NoWear testing has shown performance upgrades by reducing micropits. wear in the starved condition, and more critically to overall NoWear is a proprietary formulation patented by asset life, extending the time to starvation when compared to a SKF and is constructed with three layers. The run-in non-coated roller bearing. windpowerengineering.com

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INSTALLATION • OPERATIONS & MAINTENANCE

layer at the surface, the functional layer in the middle and the adhesion layer attaching the coating onto the underlying steel component surface.

The adhesion layer is particularly important for bearing performance when compared to other coating formulations. The formulation allows for optimal adhesion and high elasticity, while maintaining high hardness for wear protection. This strong adhesion is fundamentally important in bearing applications to prevent coating material from becoming a contaminant in the system if it flakes from the substrate.

In addition, the NoWear coating achieves running in over a shorter period when compared to other coating formulations. The NoWear formulation is the preferred solution for surface fatigue or micropitting due to its low friction and running in which reduces the induced local Hertzian stress.

Before discussing the SKF NoWear testing and verification in the main-shaft applications, it’s important to first understand the lubrication regimes the bearing operates to understand the resulting damage.

The following regimes are established.

Median time to starvation or suspension

According to the graph, the green zone or desired operating regime occurs when lubricant is correctly selected and fresh grease is supplied to the contact. Little wear of the raceways is occurring, only smoothening on the micro level.

The blue zone or mild wear regime occurs when lubricant is losing base oil content that is incorrectly selected, or insufficiently supplied to the contact. In this regime, mild wear or p*V (p: contact pressure and V: sliding velocity) like wear in the ~0-10 micron level occurs, where there is polishing but no surface distress.

The third regime is the red zone or starved regime.

The red zone occurs when lubricant is below critical levels

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in the contact.

Aggressive wear, surface distress (micropits) and high material removal are characteristics of the red zone regime.

The time it takes to damage the surface in the starved regime is shorter when compared to bearing life and the typical maintenance intervals of six months.

MPR test cases one hour of operation after Therefore, if starvation. Steel on steel (top row), SKF the red zone is NoWear on steel (2nd and 3rd row). reached in the application between maintenance intervals, surface damage is irreversible and the designed-for-load distribution across a rolling element can no longer be ensured and further damage may be accelerated due to the loss of geometry.

A common damage pattern of a spherical roller bearing (SRB) outer ring from the main bearing is shown in the following image. On the downwind row, a deep wear groove in the mid-raceway is observed and micropits fully covered the surface of the wear groove. Circumferential bands of spalling are presented on either side of the wear path, which is a result from the loss in profile and higher contact stresses at the edges.

These damages are seen primarily on the more heavily loaded downwind row.

Micropitting test results The first set of application-specific SKF NoWear tests was a component-level test. A small-scale experiment that could replicate the surface damage seen in the application. In a series of component level tests with a micropitting test rig (MPR) the objective of replicating the damage mechanism is possible.

The MPR test rig is comprised of a single roller at the center with contact to three rings.

Test conditions were set to maximize the damage within an acceptable time frame, while also maintaining application conditions. These tests would recreate the heavy damage period of the application where starvation has occurred in the contact. This would be considered “red

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OPERATIONS & MAINTENANCE • INSTALLATION

zone” conditions. Tests measured both the time to starvation and the mass after test halt compared to pre-test weight to calculate wear. The test matrix included three samples of steel on steel and steel on NoWear coated surfaces.

The results indicate the SKF NoWear coated surface significantly limits the amount of wear once the starvation (red zone) conditions are reached. Based on this component level test, the time it takes to reach the red zone conditions are scattered across the samples and no correlation is noted.

Of the six samples, one steel on steel and two steel on NoWear samples operated for one hour after reaching the starved regime. The amount of wear during the hour after reaching the starved condition for the steel/steel contact was 22.02 mg, while the wear for the NoWear/steel contact resulted 0.77 and 0.18 mg, proving that NoWear coating reduces the damage after lubrication starvation occurs.

However, since the duration of the red zone during the total life of the application is short or at the very least unknown, the next question to be answered is whether NoWear can prolong the time to lubrication starvation. As the MPR test rig was not suitable to answer the question, another test rig and matrix were established.

LAD testing results The second level of testing was designed to answer the question of whether SKF NoWear coating can prolong the time to lubrication starvation. In other words, could NoWear delay the onset of the red zone in addition to the benefits shown once within the red zone. For these tests a full bearing was needed and a test rig known as an LAD was used.

The LAD tests measured the time to starvation or sharp increase in friction. The LAD test matrix includes both the all-steel bearings and SKF NoWear coated roller bearings. In addition, two types of greases were used for the LAD testing.

A recently developed main-shaft specific grease with base oil viscosity of 670 cSt and a common wind turbine

main-shaft bearing grease with base oil viscosity of 460 cSt were chosen for these tests.

As done in the MPR testing, conditions for the LAD tests were set to replicate the application conditions. Producing a starved condition in the steel on steel samples within a time frame of approximately 100 hours was targeted in pre-tests.

For all samples, any test that had not failed at 480 hours was suspended.

The final results The results of the LAD tests indicate the SKF NoWear significantly extends the time to starvation. Differences in the performance of the LAD test samples were noted between grease types, but the larger difference is noted between the steel and NoWear coated roller samples.

Considering the NoWear sample tests were suspended at 480 hours, the median time to starvation was more than 5x compared to the non-coated bearings.

In addition, a single data point was captured that was not suspended. A 460 cSt grease sample was allowed to run out and achieved 2,584 hrs. For this sample the time to starvation is greater than 26-times compared to the median non-coated sample with the same grease.

Testing and verification of SKF NoWear during development with the coating supplier shows the coating provides advanced wear protection in poor lubrication environments and reduces surface fatigue or micropitting.

With the addition of SKF MPR testing, NoWear coating significantly reduces the amount of wear once the bearing contact is starved.

Furthermore, with the addition of the LAD testing, the reduced friction within the contact and improved run-in enables a NoWear coated roller bearing to significantly extend the time to starvation, which is critical to bearing service life.

SKF has been supplying NoWear coated bearings for applications including: • Paper machines • Marine and offshore • Fans • Compressors • Hydraulic pump gearboxes • Hydraulic motors The test results validate using SKF NoWear coating technology in rolling elements significantly increases mainshaft bearing reliability, with the goal of reducing LCoE in the wind energy segment. WPE

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Outside County Paid/Requested Mail Subscriptions stated on PS Form 3541. c. Total Paid and/or Requested Circulation of 15b (2), (3),telemarketing and (4)) (Include direct written (Sum request from(1), recipient, and Internet re(1) quest s from recipient, paid subscriptions including nominal rate subscriptions, employer requests, advertiser’s proof copies, and exchange copies.)

Outside County Nonrequested Copies Stated on PS Form 3541 (include b. Legitimate Sample copies, Requests Over 3 years old, Requests induced by a Paid and/or (1) In-County Paid/Requested Mail Subscriptions stated on PS Form 3541.

Premium, Bulk Sales and Requests including Association Requests, Requested (Include direct written recipient,Lists, telemarketing Internet reNames obtained from request Businessfrom Directories, and otherand sources) Distribution (2) quests from recipient, paid subscriptions including nominal rate subscriptions, (By Mail employer requests, advertiser’s proof copies, and exchange copies.) and d. NonreIn-County Nonrequested Copies Stated on PS Form 3541 (include Outside quested copies, Dealers Requests Over 3 years old, Requests induced by a Sales Through and Carriers, Street Vendors, Counter (2) Sample the Mail) Distribution (3) Premium, Sales Requests including Association Requests, Sales, andBulk Other Paidand or Requested Distribution Outside USPS® (By Mail Names obtained from Business Directories, Lists, and other sources) and (4) Requested Copies Distributed by Other Mail Classes Through the USPS Outside (e.g. First-Class Mail®) the Mail) Nonrequested Copies Distributed Through the USPS by Other Classes of (3) Mail (e.g. First-Class Mail, Nonrequestor Copies mailed in excess of 10% c. Total Paid and/or Requested Circulation (Sum of 15b (1), (2), (3), and (4)) Limit mailed at Standard Mail® or Package Services Rates) Nonrequested Distributed Outside the on MailPS (Include Pickup Stands, Outside CountyCopies Nonrequested Copies Stated Form 3541 (include (4) Shows, Showrooms and Other Sources) Sample copies, Requests Over 3 years old, Requests induced by a (1) Trade Premium, Bulk Sales and Requests including Association Requests, Names obtained from Business Directories, Lists, and other sources) Total Nonrequested Distribution (Sum of 15d (1), (2), (3) and (4))

d. Nonref.

In-County Nonrequested Copies Stated on PS Form 3541 (include Total Distribution (Sum of 15c and e) quested (2) Sample copies, Requests Over 3 years old, Requests induced by a Distribution Premium, Bulk Sales and Requests including Association Requests, g. (By Copies (See Instructions to Publishers #4, (page #3))and other sources) Mail not Distributed Names obtained from Business Directories, Lists, and Outside h. the Total (Sum of 15f and g) Mail) Nonrequested Copies Distributed Through the USPS by Other Classes of (3) Mail (e.g. First-Class Mail, Nonrequestor Copies mailed in excess of 10% Requested Limit mailed atCirculation Standard Mail® or Package Services Rates) i. Percent Paid and/or (15c divided by f times 100) Nonrequested Copies Distributed Outside the Mail (Include Pickup Stands, (4) Trade Shows, Showrooms and Other Sources) Electronic Copy Circulation 16. Publication 16. of Statement of Ownership for a Requester Publication is required and will be printed in the issue of this publication. e. a.

Total Nonrequested Distribution (Sum of 15d (1), (2), (3) and (4)) Requested and Paid Electronic Copies 17. Signature and Title of Editor, Publisher, Business Manager, or Owner f.

8,296

7,069

14. Issue Date for Circulation Data Below

a. Total Number of Copies (Net press run) (4) Requested Copies Distributed by Other Mail Classes Through the USPS (e.g. First-Class Mail®)

e.

8,363

Total Distribution (Sum 15cPrint and e) b.

Total Requested andofPaid Copies (15c) + Requested/Paid Electronic copies (16a)

0

0

0

0

7,069

7,112

761

884

0

0

0

0

275

165

1,036

1,049

8,105

8,161

258

135

8,363

8,296

87.2%

87.1%

0 7,069

Date

0 7,112

8,105

8,161

87.2%

87.1%

Total Requested Copy distribution (15f) + Requested/Paid Electronic copies (16a) g. c.

Copies not Distributed (See Instructions to Publishers #4, (page #3)) I certify that all information furnished on this form is true and complete. I understand that anyone who furnishes false or misleading information on this form d. or Percent who omits material information requested on the form may be subject to criminal sanctions (including fines and imprisonment) and/or civil Paid and/ororRequested Circulation h. Total (Sum of & 15f and g) copies (16b divided By 16c x 100) sanctions (including civil penalties).

(Both print electronic PS Form 3526-R, September 2007 (Page 2 of 3) i. Percent Paid and/or Requested Circulation (15c divided by foftimes 100) X I certify that 50% all my distributed copies (electronic and print) are legitimate requests or paid copies.

17.

16. Publication of Statement of Ownership for a Requester Publication is required and will be printed in the issue of this publication.

17. Signature and Title of Editor, Publisher, Business Manager, or Owner 18.

Pat Curran, Senior Digital Media Manager

December 2019 Date

Abaris Training..............................................76 Allied Moulded Products ............................17 Altech Corp ..................................................... 3 Aurora Bearing Company .........................29 Aurora Solar ..................................................52 AWEA ........................................................... IFC Axitec Solar ....................................................19 Aztec Bolting ................................................ 74 BluBanyon ..................................................... 47 Castrol ...............................................Wind Tab Chint Power Systems ..................................13 Deublin ...........................................................64 EnergyBin ......................................................34 Fall Protection Distributors .......................23 Gradient Lens Corp ....................................55 HELUKABEL USA ......................................6, 7 HYDAC Technology Corporation ............69 InterSolar North America ..........................27 Kern Solar Structures ................................ 50 Megger ...........................................................35 MOOG, Inc. ...................................................73

Nine Fasteners Inc. .....................................38 Norbar Torque Tools ....................................15 NTC Wind .......................................................71 Panasonic Eco Solutions ............................. 5 Pintsch Bubenzer USA ...............................65 PV Labels Inc. .................................................. 1 QuickBOLT .....................................................31 RAD Torque ..................................................56 RBI Solar ...........................................Solar Tab Renegade Wire Corporation .................... 37 Rotor Clip ........................................................41 S-5! ..................................................................33 Seaward Group ............................................25 SHOALS Technologies Group ...............IBC Snake Tray .....................................................46 Sollega ...........................................................29 Sungrow Power Supply Co. ......................39 Timken .......................................................... BC Traveler’s .......................................................43 Wanzek Construction ..................................61

SALES Jim Powers 312.925.7793 jpowers@wtwhmedia.com @jpowers_media

Neel Gleason 312.882.9867 ngleason@wtwhmedia.com @wtwh_ngleason

David Geltman 516.510.6514 dgeltman@wtwhmedia.com @wtwh_david

Ashley N. Burk 737.615.8452 aburk@wtwhmedia.com Jami Brownlee 224.760.1055 jbrownlee@wtwhmedia.com

LEADERSHIP TEAM VP of Sales Mike Emich 508.446.1823 memich@wtwhmedia.com @wtwh_memich

EVP Marshall Matheson 805.895.3609 mmatheson@wtwhmedia.com @mmatheson

Managing Director Scott McCafferty 310.279.3844 smccafferty@wtwhmedia.com @SMMcCafferty

Publisher Courtney Nagle 440.523.1685 cseel@wtwhmedia.com @wtwh_CSeel

FOLLOW THE WHOLE TEAM ON TWITTER @WINDPOWER_ENG

10/2/19

I certify that all information furnished on this form is true and complete. I understand that anyone who furnishes false or misleading information on this form or who omits material or information requested on the form may be subject to criminal sanctions (including fines and imprisonment) and/or civil sanctions (including civil penalties).

PS Form Form3526-R, 3526-R, September July 2014 2007 (page(Page 2 of 2 4)of 3)

80

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