Solar Power World - MAY 2012

May 2012 www.solarpowerworldonline.com

Technology • Development • Installation

INSIDE: >> DEVELOPMENTS PAGE 6

>> PROJECT REVIEW PAGE 16

>> TECHNOLOGY DEVELOPERS PAGE 42

The State of the

Solar Inverter PAGE 22

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Industrial Wireless

Industrial Ethernet

Serial Connectivity and Networking

Embedded Computing

Smart Solar Ideas from Moxa

The IA3341 Series RISC-based Industrial Embedded Computer Moxa ART 32-bit ARM 9 Industrial Processor 4 DIs and 4 DOs with 3 KV digital isolation protection 2 AIs and 2 thermocouple inputs; sensor types J, K, T, E, R, S, B, N 2 software selectable RS-232/422/485 serial ports 50 bps to 921.6 Kbps serial speed, supporting non-standard baudrates Dual 10/100 Mbps Ethernet ports for network redundancy SD socket for storage expansion

Rcore Software Platform Moxa’s Rcore ready-to-run platform makes it easy for programmers to develop embedded software. Rcore includes easy-to-use application libraries, tested bug-free sample code, and requires less time for the concept validation and development cycle enabling a faster time-to-market that meets or exceeds customer requirements. The Rcore Community also offers our partners easy access to software and technical knowledge about embedded systems, along with an interactive forum to share knowledge with embedded computing professionals.

Visit http://rcorecommunity.moxa.com/ for details.

Supports Modbus TCP library to retrieve AI and thermocouple data

Use your Smart Phone to scan for more information.

Moxa, Inc.

Tel: 1-888-669-2872 Fax: 1-714-528-6778 usa@moxa.com www.moxa.com

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Editorial Advisory Board

THE

FI RS T

WO RD

The Storm Clouds Of War Are Gathering

Natalie Wiener Solectria Renewables Jose Gomez Ingeteam Raheleh Folkerts Renewable Energy Systems Americas Steve Hogan Spire Gary Mull Westinghouse Solar Devon Cichoski SolarWorld Marcelo Gomez Unirac Justin Barnes North Carolina (State University) Solar Center Scott Wiater Standard Solar

T

he storm clouds of war are starting to gather over solar policy. We are seeing early skirmishes going on already on both the national and state levels. But this is only the beginning — and as Winston Churchill once admonished us, we can’t run away because it will only embolden our enemies. We must join the battle without flinching and meet it before it gets out of hand.

I first felt the chill hand of war touch my shoulder when I read a report discussing the latest funding bill for the Department of Energy will be cut 4% overall and a whopping 17% in the areas of renewable energy, including, of course, solar.

The current House of Representatives is attempting to cut off the money which funds so much of the innovation in renewable energy. To paraphrase conservative hero Grover Norquist, they are trying to shrink the solar industry to the size where they can drown it in a bathtub.

In an industry that’s experiencing breakthroughs at a breathtaking pace, cuts to research could cripple the the industry. How does this make any rational sense?

But there’s an even more insidious front opening in this war that I want to bring to your attention.

Meet ALEC (the American Legislative Exchange Council). Who are they? Think of them as the Legal Zoom of state-level legislation. Legislators come to ALEC with a subject they want to introduce legislation on, and ALEC will helpfully write it for them — and spread those laws across the rest of the country.

They’ve been in the news a lot lately for being behind an Arizona immigration law (mimicked in South Carolina and Alabama) and the Stand Your Ground law in Florida and 11 other states. But they feel they’ve done enough in those areas and are turning their sights on renewable energy.

ALEC has been extraordinarily successful in getting laws passed in the wake of the 2010 elections (known by some as the Tea Party elections), so they know how to do this. With state legislatures often under the control of ALEC-friendly representatives and senators, it could spell doom for the renewable energy supports that have made the solar industry the fastest growing industry in the United States.

Thankfully, ALEC is making its plans clear, so we can prepare for this battle on a state-by-state basis. Believe me, this is going to be the mother of all battles.

You must hold your federal and state representatives accountable. Be evangelists for this industry everywhere you go — block parties, offices, churches. Wherever you have a chance to talk to people about the advantages of solar, do it. Urge your Facebook friends and Twitter followers to call their representatives to demand they stop this attempt to destroy your livelihood — and then, after that, urge them to vote in November. Yes, it’s that important.

This is going to be a long war. Will you join me in this fight?

What do you think?

Discuss this, and other solar issues at www.engineering exchange.com

Frank Andorka Editorial Director fandorka@wtwhmedia.com

www.solarpowerworldonline.com

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MAY 2012 • vol 2 no 2 EDITORIAL

SALES

Editorial Director

National Sales Manager

Frank Andorka • 440.234.4531 x110 fandorka@wtwhmedia.com

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w w w. s o l a r p o w e r w o r l d o n l i n e . c o m

contents

6 D e pa r t m e n t s

06 Developments 11 Breakthroughs 14 Inverter Insider 16 Project Review 19

Racking and Mounting

46 Products 52

Contractors Corner

Ad Index

v o l

2

n o

2

F e at u r e s

22 The State of the Solar Inverter: Installers

Inverter installers share their thoughts on the solar inverter industry.

26 The State of the Solar Inverter: Manufacturers

Inverter manufacturers share their thoughts on the future of solar inverter technology.

30 The Grid-Tied Smart Inverter of the Future AE Control Solutions discusses laying the foundation for the next-gen solar inverter.

51

•

05 Policy

2012

42

01 The First Word

May

38 Sealing Molten Salts in CSP

About the Cover:

Garlock Sealing Technologies explains how to seal molten salts in concentrated solar plants.

This month’s cover photo was provided

by Brightergy of Lenexa, Kan. The

42 Out of the Incubator

Pythagoras Solar has developed breakthrough BIPV technology.

solar installation at

photo shows a a Kansas City high school.

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[POLICY]

A CES Discussion With Senator Jeff Bingaman (NM)

Solar Power World Editorial Director Frank Andorka reached out to Senator Jeff Bingaman (D-NM), current Chairman of the Senate Energy and Natural Resources Committee. On March 1, Senator Bingaman introduced legislation to create the Clean Energy Standard Act of 2012, which would help all clean energy sources progress by creating one national standard for clean energy sources. This would eliminate some of the uncertainty surrounding clean energy and potentially encourage private sector investment.

Senator Bingaman took time out of his busy schedule to respond to SPW’s email questions. It should be noted that Senator Bingaman will be retiring after this session.

That being said, their on-again, off-again nature has also provided hurdles for planning. The Clean Energy Standard would spell out the rules for the road for the next 20 years or so, in a way that would make planning easier for all clean technologies.

The crediting of clean energy is tied to the amount of carbon dioxide that a generator emits per megawatt hour generated as compared with a new, highly efficient coal plant. This lets many technologies receive partial credits for emitting less carbon than coal, and means technologies that emit zero carbon dioxide like solar, wind, nuclear, or hydro, receive the greatest incentive. This way, the market will adjust to figure out the optimal mix of technologies and fuels.

SPW: What sparked your interest in developing a Clean Energy Standard (CES)?

SPW: I know you and others have introduced similar legislation in previous sessions. Do you foresee that the legislation has a better chance of passing this session than in past ones, and if so, why?

Senator Bingaman: President Barack Obama called for a Clean Energy Standard (CES) in his 2011 State of the Union Address. In the past, Clean Energy Standards in the Senate have received bipartisan support with Senators [Peter] Domenici (R-NM) [Editor’s Note: Senator Domenici retired from the Senate in 2008 because of health concerns.], [Lyndsey] Graham (R-SC) and [Richard] Lugar (R-IN) and others, supporting their own versions in the past. In the current difficult political environment, my hope is to restart a serious conversation on clean energy by putting out a proposal based on ideas that have had bipartisan support in the past.

SPW: Why do you think a Clean Energy Standard is critical to the development of cleaner technologies in the United States?

Senator Bingaman: The CES is critical because it provides a transparent and long-term market signal that clean energy developers can plan around. Right now, we have a series of tax incentives that has been helpful to the industry.

Senator Bingaman: I’ve introduced a Renewable Electricity Standard (RES) that would set a standard for utilities to generalize a percentage of their electricity from renewable sources. More than 50 percent of states have implemented a form of an RES, but no Federal standard exists. There is no question that it’s going to be difficult to get any significant energy legislation, like a CES, passed this Congress. Focusing the discussion on the concept is an important step, though, to improve the legislation and its prospect for passage in the future.

SPW: What is your strategy to get this bill passed?

Senator Bingaman: In terms of strategy going forward, I look forward to meeting with both Democrats and Republicans to discuss their concerns and see if there’s anything we can do to address those. SPW

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Senator Jeff Bingham D-New Mexico

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[DE VELOP MENT S

RESI D ENT I A L ] K at h ie Z ip p / As s o c i ate E di to r

© Copyright 2012 Solar Innovations, Inc. All Rights Reserved

Smart Solar Architecture

© Copyright 2012 Solar Innovations, Inc. All Rights Reserved

Pennsylvania-based Solar Innovations, Inc. offers some innovative architecture for residential and commercial solar installations. The company uses aluminum and wood materials to create glazed structures, skylights, windows, doors and more.

Greg Miller, Alternative Energy Design Specialist with Solar Innovations, Inc., discussed the company’s canopy system at the PV America show in San Jose this March. He explains that PV panels can be integrated into such architecture with polycarbonate and glass and

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actually sealed and glazed in. This creates a complete shell. Modules can also be integrated into sunrooms, façades, conservatories and more. Miller uses an example of a recent installation at a university. Solar modules generate power for the greenhouse they are glazed into.

The company manufactures and designs the whole system from extrusions up, offering engineering, manufacturing and some installation services. These systems are built in kit form and shipped nationwide. SPW Solar Innovations, Inc www.Solarinnovations.com

Solar Innovations Inc. can include solar panels in many of their custom architecture designs for residential and commercial installations.

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[D EVEL O PM ENT S

CO M M E R C IA L ]

Racking on Rooftops in Irvine Nikken Inc.’s 680-KW rooftop solar system is one of the largest in Irvine, California. The system spans over 100,000 square feet across several rooftops.

Because of the large number of skylights on the roofs, it was uncertain if enough PV modules would fit. Sollega’s flexible solar racking system made it possible to work around these obstacles and to maximize the harvestable rooftop space. A total of 2,224 InstaRacks with a 10 degree tilt angle were installed to mount 2,886 solar modules.

EPC for the project PermaCity Solar found the system easy and quick to install. The company

spent less time on the roof and had fewer parts to manage than with other ballasted racking systems. Also, the two companies’ engineering teams were able to keep roof loading to a minimum by balancing ballast pavers and roof anchors. Low weight was a crucial requirement in making the project a success.

With an estimated power generation of 900,000 kWh per year, Nikken Inc. will be able to generate up to 80% of its electrical requirements with clean solar power. SPW Sollega www.sollega.com

Project Facts Modules

2,886 Sharp 240W

Inverters

2 Solaron 333 kW

Array Area

73,413 sq. ft.

Commissioning Date

September, 2011

The InstaRack10’s flexibility made it possible to work around skylights and mazimize harvestable rooftop space.

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Harnessing the power of the sun.

Guaranteed.

RPS TL Series

With over 1.2 GW of installations worldwide, Bonfiglioli is one of the world’s leading suppliers of power conversion systems for utility and commercial-scale PV power plants.

The Bonfiglioli Vectron Center in Germany is the hub of innovation for developing reliable, high performance modular and scalable inverter systems in Master-Slave and multi-MPPT configurations. Bonfiglioli’s PV solutions provide design flexibility, and advanced grid integration and stability features such as active/reactive power control, voltage and frequency ride-through, and active power reduction for over-frequency response.

Along with industry diversification, Bonfiglioi has the global footprint and financial stability to remain an engaged, dependable partner over the lifetime of the project.

Guaranteed.

July 10-12, 2012, Moscone Center, San Francisco West Hall, Level 2, Booth 8311 Bonfiglioli Highlights: 25+ years experience in proven power conversion technology for the renewable energies Inverter power ratings from 300 kW to 1.40 MW (up to 2.80 MW power station) Maximum inverter efficiency of up to 98.6% Lower maintenance costs and longer expected lifetime

Bonfiglioli USA 3541 Hargrave Drive, Hebron, Kentucky 41048 - BonfiglioliUSA.com\PV

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[ D EVEL O PM ENT S

Taming Cables New York-based Snake Tray offers a variety of cable management solutions for solar installations. Particularly, the company’s utility-grade dual panel pole mount system accommodates municipal and private solar installations mounted on existing or dedicated utility poles. These systems are developed in conjunction with micro-inverters, which allows 2.5 times more solar power capture from a single-pole site.

The company also offers handbendable cable pathways that make installation easier, including a system for solar racks, a device that snaps cables into place under panels, a ballasted roof mount anchor for cable trays and conduit, and a combiner box. Snake Tray products are made in the USA using solar power generated from the company’s own roof top solar array. SPW

Snake Tray www.snaketray.com

An Inverter with Quick Installation and Long Life

Magnetek’s 1-MW, 1,000-V air-cooled E-Force photovoltaic inverter is designed for grid-tied large solar applications, such as ground-mount systems. The device integrates two 500-kW inverters in one enclosure, which can reduce the skid footprint by as much as 30% compared with independent 500-kW competitive inverters. The company says the units achieve peak and CEC efficiencies of 97.9% and 97% respectively.

Two Maximum Power Point Tracking (MPPT) algorithms maximize the energy produced under varying light conditions. Magnetek’s switching technology incorporates large capacity Insulated Gate Bipolar Transistors (IGBTs), which improve service life. Additionally, selfdiagnostics and remote monitoring

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UT IL IT Y]

allows monitoring energy generation and operational status. VAR control is provided through power factor adjustment from 0.95 lead to 0.95 lag as standard. Optional MV transformers can provide distribution level output voltages of up to 34.5 kV. Additional grid support options include Low Voltage Ride Through (LVRT).

The E-Force is qualified to display the ETL certification mark, which indicates the device meets product safety requirements for connection to a United States or Canadian utility power grid or a grid in any country where UL and CSA standards are accepted. SPW Magnetek www.magnetek.com

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20111216_Solar_World_Full.pdf

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In the world of solar...

C

M

Y

CM

...it’s a good sign.

MY

CY

CMY

K

Find out how Solar Frontier’s CIS modules yield more kilowatt hours.

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[ B REAKT HROU G H S ] Fr a nk A n d or ka /E d it or ia l D ire c t or

The Revolution in 3-D MIT researchers have produced solar cells in three dimensions, increasing their solar output by up to 20 times that of traditional panels.

I

nnovation in the solar industry is coming at such a rapid pace that sometimes it’s hard to keep up.

Rarely does a day go by that one school or another isn’t sending a press release talking about new efficiency levels.

But few people have challenged the basic idea of using flat panels to collect solar energy from the sun. A multidisciplinary team of researchers at MIT, however, has constructed a model that could increase efficiencies anywhere from twice as much to 20 times as much.

How did they do it? Well, nature provided them with clues— and their discoveries could revolutionize the way solar panels are constructed and manufactured in the future.

How Plants Do It Marco Bernardi, a graduate student in MIT’s Department of Materials Science and Engineering, says the idea of making solar structures three dimensional came to him and fellow research scientist Nicola Ferralis, when they pondered how plants use energy to grow.

“We know that plants use sunlight in 3-D by putting out as many different solar absorbers as they can in different directions,” Bernardi says. “So we thought, ‘Why couldn’t we do that with solar panels?’”

In response to that question, Bernardi, Ferralis and Jeffrey Grossman,

the Carl Richard Soderberg Career Development Associate Professor of Power Engineering at MIT, set about building cubes and towers that extend upwards in threedimensional configurations. They initially used a computer algorithm to cycle through many different potential constructions before finding the right one.

The team took into account several factors in coming up with their design, including cell efficiency. Bernardi says the most efficient array would have been more complex, like a cube where each face is dimpled inward. But what was most important to them was making sure whatever design they chose was also affordable to manufacture.

“We don’t want it to be too expensive to make,” Ferralis says. “The plunging prices of solar panels has allowed us to think about them in new ways that would have been impossible to imagine 10 years ago.”

Bernardi says the power output between optimized shapes and a simpler cube is only about 10% to 15%, which a better overall performance of the towers would balance.

Two small-scale versions of threedimensional photovoltaic arrays were among those tested by the team on an MIT rooftop to measure their actual electrical output throughout the day.

Photo: Allegra Boverman

The Way The System Works Typical flat solar panels can only collect solar energy for four to five hours a day. With 3-D structures, there are more vertical surfaces to capture sunlight at different times of the day. It allows the solar cells to produce more uniform www.solarpowerworldonline.com 5 • 2012 SOLAR power WORLD

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[ B R E A KT H RO U G H S ]

power output over the course of a day, over different seasons, and through cloudy or shadowy periods.

“These structures are efficient in picking up solar rays even on cloudy days,” Ferralis says.

“They also gather solar rays as the sun gets lower on the horizon, which means that it’s more adaptable to areas of the world that don’t have bright sunshine all the time.”

The MIT 3-D towers are shaped like an accordion because the team believed it would be easier to fold up and ship and then expand once they’re on site.

But it’s one thing to test their models on a computer. It’s completely another to actually test them on the roof of a building.

“We set up to test the predictions from the simulations with real prototypes on top of real buildings,” Ferralis says. “We used 3D printing technology to make the prototypes, and we developed the power electronics to measure the performance of four different shapes at the same time.”

At first, it looked as if the experiment would be a complete failure. Nearly two weeks went by without a single, fully sunny day. Then they looked at the data, which proved how well their 3-D PV towers performed on cloudy days. They were excited by what they found.

“The loss of power due to clouds was actually mitigated in the 3D shapes compared to flat panels,” Ferralis says. “That’s where we see the most improvement.”

As a result, the 3-D towers also track the sun naturally without the use of solar trackers, Bernardi says.

“You could never use trackers in residential solar arrays,” Bernardi says. “These cells remove the necessity of using them while keeping the same performance.”

Marco Bernardi

Marco Bernardi is a Ph.D. candidate in the Dept. of Materials Science and Engineering at MIT.

Nicola Ferralis

Nicola Ferralis is a research scientist in the Department of Materials Science and Engineering at MIT, where he is the Director of Experimental Research for the Grossman Group.

What’s The Future The team at MIT has only tested a few towers so far, but they will be testing groups of them in the near future to simulate more traditional arrays. The researchers expect to use this data to further refine their towers in anticipation of the eventual commercialization of the technology.

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Ferralis wants to make it clear that the towers they’ve developed are not tied to any particular PV technology. They can be used with thin-film or crystalline modules.

The team is working on a cost analysis to see what a commercialized system would cost.

“We’ve already had a lot of interest from several companies in our design,” Ferralis says. “We don’t see any barriers to commercializing this tower technology within the next five years or so. We’re hoping that by thinking of solar power in a radically different way, it will spur further innovation and development.

“Furthermore, we see a lot of potential of this technology when applied to architectural integration,” he continues.

“The maximum benefits of the 3D-PV technology are obtained when we think to the solar generation with an integrated and collective approach rather than an insular ‘single-installation’ approach that is currently employed. This effort seeks to not only find the optimal configuration of installations of solar modules in buildings (beyond the rooftop), but also how to maximize energy collection by benefitting from reflections from the neighboring buildings.”

“We’re obviously just at the beginning of this exciting process of discovery,” Ferralis says. “We’re not entirely sure where our research will take us, but we’re proud to be on the cutting edge of this exciting industry.” SPW

Discuss This and other Solar issues at www.engineeringexchange.com

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[I N VE RTE R

INS I D ER]

AETI

Integrated Solar Inversion Station (ISIS) 1MW

A

represent all levels of PV array production for its CEC. AETI also uses unipolar PV arrays with open circuit voltages up to 1100 Volts DC to obtain 10 to 20 percent more power per string, which also saves up to 40 cents per watt in costs over bipolar designs.

Next is long-term reliability.

The use of noisy high-velocity fans with air intake from the ground fail because of sucked in dust and grit that destroys bearings. Instead, AETI uses vortex-filtered air intake from above with multiple quiet, small and more reliable fans operating at lower velocity for longer life, greater reliability and far less tare loss than competitive offerings.

By combining positive-pressure fan cooling with liquid cooling of the 500-KW, UL-tested power

merican Electric Technologies has been a leading provider of power delivery solutions to the traditional and renewable energy industries for more than 65 years.

When AETI designed its 1.0, 1.5, 2.0, 2.5 and 3.0-MW integrated solar inversion systems, utilities identified three design objectives that were not being met: improved efficiency and lower tare loss, long-term reliability and lower integrated installed cost.

Regarding efficiency, more customers are requiring Nationally Recognized Test Laboratory (NRTL) witness-tested California Energy Commission (CEC) efficiency of 97.5% or better. AETI selected the testing voltages of 650, 775 and 900 volts DC, which

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modules, AETI’s inverter operates up to 55°C without output power derating while dramatically extending the life of the power modules.

This results in megawatts of production power produced even in the sunniest and hottest climates for many years.

Finally, AETI lowers installed costs by integrating the PV master recombiner, DC & AC disconnect switches, inverters, AC panelboard and MV transformer and switchgear together as one NEMA 3R/4 system. SPW

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[PROJ ECT

REVI EW ] K at h ie Z ip p /A s s oc iat e E d it or

The Home of the

Future is Here Now Nexus EnergyHomes builds net-zero homes available at market price

Nexus EnergyHomes’ entire energy electrical system is tied to the electrical or utility grid for net metering. Power is produced during sunshine and drawn from the grid at night, or in periods of extensive cloud cover, to produce annual, zero or near zero electricity demand off the grid.

I

magine opening your mailbox and never seeing another electric bill. This may seem like a dream for the future, but with today’s technology it’s actually possible to build houses that produce as much power as they generate. “Net-zero” homes have made headlines here and there, but at such high prices they are more of a novelty than an option for today’s house hunters. One company, however, set out to change that, and succeeded. Such homes are available— with people living in them right now— 16

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at an affordable market price.

Homebuilder Nexus EnergyHomes has done some innovative work in historic downtown Frederick, Md. The company’s 2,000-sq ft, single-family dwellings in the 55-lot North Pointe GeoSolar Community are the first of their kind. These EnergyHomes sport features including a PV solar array, geothermal heating and cooling, energy recovery ventilation, LED and CFL lights, Energy Star Appliances, windows with high-performance low-E glass and structurally insulated panels.

Such energy-efficient options can be found in similar home designs but with significantly higher price tags.

“Anyone can spend a million dollars and create a net-zero home,” says Mike Murphy, construction division president for Nexus. “But to do it at market price was quite a feat.”

Murphy says from the beginning he and Nexus EnergyHomes President Paul Zanecki were determined to find a formula to balance energy efficiency and cost.

“We knew that in this economy,

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Besides being energy efficient, North Pointe homes are loaded with sustainable materials, such as bamboo flooring, recycled glass countertops, and carpet with recycled content.

there was a demand for an affordable net-zero home,” Murphy says. “Our goal was to offer these homes to the masses, to change the way homes are built in this country.”

But finding the right recipe wasn’t easy. The team spent several years working with the National Association of Home Builders (NAHB) with funding from Building America, a Department of Energy sponsored program.

“It was more than adding some insulation and slapping on solar,” Murphy says. “We researched every piece of the home design right down to the screws, drywall and paint. We took a holistic approach, peeling back the skin and looking inside to see all the parts and how they work together harmoniously.”

Murphy admits researching and testing was a challenge, but didn’t find it a chore. He viewed the scrapping, putting back together, and going back to the drawing board as fun. The real challenge, he says, was working with architectural designs that had already been approved by the local historic preservation committee. Obviously, historic houses don’t usually host solar, but the parties compromised on aesthetically-pleasing Schüco panels— the sleek, black modules hide well against charcoal shingles. The homes were actually the first historic buildings in the country to have solar approved

on the front and side of their roofs.

Another challenge Murphy encountered was getting the HVAC (heating, ventilation and air conditioning) contractor to understand the design. He says the contractor had to practically throw his way of looking at a home out the window and work with a design that hadn’t been developed yet. But again, the NAHB intervened to help with the analytics of Nexus’ plan. Zanecki agrees the process was challenging, but worth it.

“The approval process is never fun,” he says, “but the city itself and all government leaders could not possibly have been more supportive. Their desire to get this up and going helped us move along.”

All the hard work paid off when the company finally broke ground in January 2011 and opened sales in the summer of 2011. The final models run for a mere $285,000-$320,000, considered affordable for the Washington D.C. area.

The home maintains traditional architecture but inside it’s strikingly sophisticated. Humidity is monitored and kept at comfortable levels year-round, along with a constant temperature across four floors. Mold spores, mildew, and animal dander are filtered through a whole house HEPA filtration system to ensure the highest www.solarpowerworldonline.com

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quality indoor air—a godsend for those who suffer from allergies. Such features have made homeowner response overwhelmingly positive.

“People enjoy a sense of luxury and livability,” Zanecki says. “The home is well-crafted and solid. For example, 7-in. walls provide peace and silence on one of the busiest streets in the city.”

Murphy says the neighborhood has come around full circle from the former remnants of a HUD revitalization project that reached a standstill with the recession.

The homes have attracted national attention with their EVHA 2012 Builder of the Year win, as well as the EVHA New Homes Gold Award for Production in Moderate Climate.

But even with the great success the company has already experienced, Murphy and Zanecki say it’s just the

The core of every Nexus home is NexusVision, an energy management system that allows homeowners to better manage their homes’ energy use and production.

The system monitors energy consumption in every room and level of the home. Owners can access this data in real time on any computer, iPad or iPhone.

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beginning. For them, the question is always how to continually innovate. “I want to make homes that are better in every way— integrating all the best performing technologies under one roof,� Zanecki says. “Until that vision is realized, I keep pushing.�

Even from home to home within the North Pointe Community, features have changed as technology progresses. Murphy says he wants to ensure Nexus’ homeowners are offered the most current, cutting-edge technologies available. Of course, price is also a concern, but he is thankful for falling solar prices, large quantity discounts and home-system financial incentives that lower costs for homeowners. “Initially, our homes might be 7 percent more expensive than conventional homes, but the overall cost of homeownership is much less,� he says.

Financial incentives beyond the reduction or elimination of power bills can include county incentives, Maryland state grants, and federal tax credits, and the utility savings alone will immediately outweigh the slight

ÂŽ

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increase in mortgage payments.

Another area that will continually see innovation is with the company’s NexusVision Smart System, a web-based tool that tracks home energy production and consumption. Homeowners can adjust climate controls, switch lights on or off, and control their security system from any computer or even their smart phones. In the future, this system may practically allow your home to talk to you, letting you know you left the door open or it’s time to change a filter.

The idea of a futuristic “smart house� is cool, but Zanecki says the system’s real value is allowing homeowners to easily monitor their energy use.

Nexus builds the home so that it is capable of achieving net-zero, but it’s up to the homeowner to maintain it. “If little Johnny is upstairs with five TVs, his stereo, phone charger and Xbox, and the home is using more power than it’s producing, NexusVision will show it,� Zanecki says. “It’s a measuring tool that we hope will help people become increasingly aware of how much energy they’re using, and learn from it.�

More people will be able to use such tools in their own net-zero home as the company takes their models elsewhere—they’ll need to, as North Pointe is averaging selling a home a week. Of course, Nexus will have to adjust their recipe for hot South Carolina summers and the area’s $250,000 to $260,000 market. Sites in Philadelphia must also be fitted for cold winters. It’s a lot of work, but Murphy says he loves it. “Paul and I have a passion for this and it’s not even a job for us, just a fun journey and something we love to do,� he says.

Zanecki says he hopes the homes will offer freedom from rising energy costs, projected electric shortages, and reliance on foreign fossil fuels. He projects a strong 2012 and beyond for Nexus. “It’s not hard to understand why we are succeeding in a market where other builders are struggling to make sales,� he says. “When you can buy a new home with the highest green-building technology and certifications combined with a modern layout and amenities, all for the same price of traditional homes, why would you choose anything else?�

To learn more about Nexus EnergyHomes, neighborhoods and communities, or Nexus custom homes, call 410.604.2870 or visit www. nexusenergyhomes.com SPW

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Fr a n k A n d ork a/ E di to ri al D i rec to r

No Holes Necessary S-5!’s clamps sped the process of installing solar panels on a rental care facility in record time.

The Phoenix Sky Harbor International Airport wanted to install a 5.4 MW solar system on its rental car facility. But before it could happen, the managers had two problems to solve.

Covering the facility are three bowl-shaped metal roofs. Punching holes would defeat the purpose of using such a durable material. In addition, the project needed to be done quickly to qualify for funding under the Arizona Public Service Co.’s Renewable Energy Incentive Program.

So the managers went in search of a mounting system that would allow them to solve both issues.

They found their answer solution with S-5!.

“The airport was under a tight deadline from the government to get the project done,” says Shawn

Haddock, product manager for S-5.

“It was installing 12,500 SunPower panels and needed to get it done in 4.5 weeks. The managers decided that our S-5! Z-Mini clamps were the way to go.”

S-5! Z-Mini clamps are mediumduty seam clamps that have one setscrew instead of two. When the one-point setscrew goes into the roof, it dimples instead of making a hole. That way, the roofing warranty isn’t voided.

The clamps speed the process because of their easy installation,

Type: Roof Mount Size: 5.4 MW

Phoenix Sky Harbor International Airport Rental Car Facility PV Installation Vital Statistics

Energy Generated: 51% of total for facility Number of Panels 12,500 320-W panels Total Install Time: 4.5 weeks Crew Size: 20 people each day Best Installation Day: 700 panels by three crews Number of Roofs: 32 Amount of Time Worked (Per Week): 8 hours a day, 5 days a week Savings: $4.7 million over 20 years Racking Company: S-5!

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S-5! Clamp Installation Haddock says. They are also strong: S-5!

Minis have as much as 2,500 pounds of holding strength and can be installed in around 21 seconds.

“Our clamps allow for thermal movement and avoid pinning the panels avoiding problems,” Haddock says.

“When the sun hits it in the morning, the metal can expand up to one inch per day, and then at night it contracts.”

Furthermore, the Minis allow installers to mount the panels without having to cut holes in the roof and place pipe boots at each penetration. This is a rather lengthy process and creates potential leak points in the structure of

First, determine how to position the clamp and which side of the clamp to load the setscrews into.

When attaching to machine-folded seams (regardless of panel profile and geometry), S-5! clamps are designed to engage the seam as shown (4). For horizontal seam applications, the setscrews must be accessible from the top for tightening (1). On many snap-together type seams, the setscrews are opposite the open (or overlap) side of the seam (2). On some seams, this aspect of clamp orientation is not critical (3,5).

the roof.

On the best day of the installation, crews installed 700 panels with three crews of about six people (the average speed of installation was 150 panels per day). There were 33,000 S-5! Minis — or 10,030 clamps per roof — used on the project.

“If it’s not the largest metal rooftop installation in the United States, it’s one of them,” Haddock says. “We’re just happy to have played a part in helping them with their deadlines without hurting the roof.” SPW

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Why Metal Roofs The concept of combining photovoltaic arrays with standing seam metal roofing is growing—and for good reasons. A standing seam metal roof has a life expectancy consistent with that of framed PV modules. A 30-year power source on a 40-year roof, along with zero-penetration technology creates the most sustainable roof system available with alternative power generation, all without compromising the roof’s warranty.

Source: S-5! Solar Introduction, www.s-5.com

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I N S TA L L E R S

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The State of the Solar Inverter:

Insights From Installers

Installers share their likes and gripes with solar inverters

Kat h i e Zi pp/ Asso ci at e E di t o r

Inverters are a critical component of any solar system. But with so many options, perhaps now is a good time to examine important inverter characteristics, trends, issues and what to expect in the future. Who better to ask than the installers who work with these devices every day? After interviewing representatives from four companies across as many states, here—from likes to gripes—is what they had to say.

Solar is such a young industry that anyone who’s been in it for more than a few years is practically a veteran.

Technology progresses so quickly these folks have seen rapid innovation. From DC optimizers to grid-tied models to the ability to monitor production on an iPhone, these developments make their job easier—and they appreciate it.

“Inverters are a lot better than they were ten years ago,” says Christopher Maingot of Superior Solar in Longwood, Florida.

He remembers a time when inverter manufacturers only offered five-year warranties. Now upgraded warranties can extend twenty. Alex Norman of Lenexa, Kansas’ Brightergy has also been in the industry for some time. He remembers when SolarCity was “the big guy,” and since has seen lots of companies start, fail and take off. The development of maximum power point tracking (MPPT) is what he’s thankful for. The technique allows solar inverters to get the

maximum power from the PV array.

Inverters have also gotten much more efficient, but—although this is an important development—most range from 96 to 98 percent. So efficiency isn’t exactly a distinguishing factor for picking one out.

Considerations When Choosing An Inverter For Maingot, choosing an inverter is all about proven technology.

He prefers to use inverters that have been around for years.

“I don’t like to be anybody’s guinea pig,” Maingot says. “Stability of the company and its reputations are important for us. We prefer to use inverters from tried and trusted names in the industry.”

Maingot says price is a driver—but not as much as quality.

“Our mission is to sell quality, and the best quality isn’t always cheapest,” he says. “But quality, in the long run, is cheaper than anything else.”

J. Wesley Cravens of Quanta Power Generation in Greenwood Village, Colorado says when he looks for an inverter, he puts the client’s needs first and foremost.

“It’s really what the client wants as far as system specification,” he says. “We put out the RFP (request for proposal) and then evaluate the inverters based on technical requirements.”

Other characteristics important to Cravens are accessories, options and if the inverter can provide more power than it’s rated for.

• • Installers put in a solar system at a Kansas City high school. The right inverter choice differs from project to project and depends on preference, technical specs and other characteristics. www.solarpowerworldonline.com

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Alex Norman Brightergy http://brightergy.com

Christopher Maingot Superior Solar www.superiorsolar.com

J. Wesley Cravens Quanta Power Generation www.quantapower.net

Microinverters Microinverters have grown to become a popular option for solar installers. Randy Velker of Crossville, Tennessee’s Simple Energy Works says he’s a fan.

“If I can put a microinverter on, I will,” he says.

Microinverters reduce shading and stringing issues that can otherwise bring a whole series of panels offline. They also provide the ability to monitor each inverter and panel individually, as each has their own IP address connected to a broadband modem. This also allows viewing the system’s complete energy history and targeting problems at their sources.

“Last week, we had a large system of 160 modules that was underproducing,” Velker says.

“Through microinverter monitoring, we were able to link the problem to five panels in the middle of the array, get in there and fix the problem.

Without microinverters we would have had to test every model. They certainly help us troubleshoot.”

Velker also likes the ease of

system design microinverters provide, allowing for the adjusting of modules to separate slopes. This advantage is great for residential installations, where homeowners also enjoy monitoring their systems’ energy production on their smartphones.

Norman agrees that microinverters are great for residential installations, but says their use should stop there.

“Microinverters are an intriguing idea,” Norman says. “They have a long warranty—about 25—years, and increase system transparency on smallscale projects. But an inverter on every module in a 110-unit system is too much equipment—too much can go wrong.”

Norman prefers to have one or several main inverters to simplify the system. This allows unplugging one central inverter or taking a few off the wall instead of replacing so many units.

Still, Velker thinks microinverters could revolutionize the solar industry.

He says it used to take years of experience to become fluent in system design, but microinverters are making it simple, and a lot of electrical knowledge unnecessary.

“They’re changing the landscape,”

Velker says. “Many start-ups are using microinverters because it’s easy. It opens the doors to those entering the solar market.”

Inverter Issues Even though inverters have come a long way, installers say there’s still room for improvement. Higher reliability and lower costs would obviously be nice, but Norman says so would technical support.

“Demand is greater than available expertise in the solar industry,” Norman says. “It’s hard to know if you’re installing the inverter wrong or how much power the

Randy Velker Simple Energy Works www.simpleenergyworks.com

• • Microinverters can reduce shading and stringing issues, as well as monitor panels individually making it easier to find problem sources. On the flip side, one inverter per module means more equipment to go wrong.

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T H E S TAT E O F T H E S O L A R I N V E R T E R

system can actually handle.�

Norman says many times installers rely on string-sizing calculators, but if these aren’t accurate, power may be clipped at high points, reducing inverter life. He would like more transparency for designers who rely on manufacturers to tell them the best way to configure DC input. “There’s a heavy reliance on the manufacturer to provide recommended data,� Norman says. “It’s not ideal, but that’s the reality of it. We expect them to provide support.�

Cravens says most of his inverter issues revolve around international voltage limits.

For instance, a European inverter may be designed for 1000-V systems, but it’s really only suited for 600V in the United States.

“The voltage limits don’t transfer,� Cravens says. “Companies just want to bring the design over quickly, but they’re not always thinking about the end user.�

For example, Cravens says he just worked on a project in Mexico and had a difficult time finding a company who makes inverters with Mexican output voltages. He has the same problem with monitoring capabilities, saying none speak a language that everyone knows.

Cravens would like to see companies adapt to a single communications protocol to make monitoring easier.

efficient and don’t require cooling associated with transformers. He even recalls seeing one solar farm with a liquid-cooled inverter that uses a radiator to cool the system. Maingot notes it was much quieter than other designs.

Also, better technology will lead to longer inverter warranties. Right now panel warranties are about twice that of inverters. This is because inverters, like most electronic devices, break down over time. Therefore, Maingot knows he will have to replace inverters at least once during the life of the system, so it makes sense to upgrade warranties up front. It’s cheaper to pay for the extended warranty than all new units. “We live in a world where we can monitor system data on our smartphones,� Maingot says. “Overall, I’d say technology is rapidly getting better.� SPW

Future Developments Maingot expects more transformerless inverters, which he can see his company using. Such units are lighter weight, more

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The State of the Solar Inverter:

Full Speed Ahead

The race is on for higher inverter efficiencies, voltages, controls and standards.

Fra n k An do rk a / E di t o ri a l Di re cto r

Prices of photovoltaic (PV) solar panels

plunged nearly 51% last year. The downward spiral in panel costs have made solar the fastest growing energy segments in the United States.

As installations have risen, there has been increasing pressure on inverter manufacturers to build more powerful, efficient and standardized products. Those three areas of inverter development are where manufacturers are focusing their energies. The inverter industry is changing rapidly, and industry experts predict the companies that don’t adapt will wash out.

“We’re in the infancy of the inverter industry,” says Steve Levy, vice president of sales for Bend, Ore.-based Advanced Energy. “It’s an exciting time to be investing in this space.”

could handle 2.5-MW systems. Now they’re getting larger.”

Skibinski says AETI doesn’t play in the commercial and residential-scale markets — they are strictly utility-scale players.

“All utilities are looking for 1000-V inverters,” Skibinski says.

“People have been hesitant to build so large because the National Electric Code (NEC) doesn’t mandate them to be that big. So why fight the NEC?” Such inverters, however, are standard in Europe, and will eventually become standard in the United States, he says.

Alan Beale, director of sales-and-marketing for San Josebased REFUsol USA, says there are even companies that are putting 1500-V inverter pilot projects in the ground.

“There’s a handful of companies doing 1500-V inverters and 1500-V panels,” Beale says. “In another two years, that’s where the entire industry will be.”

Higher Power The first thing John Skibinski, vice president of new markets development at Houston-based AETI, wants people to know about the inverter market is that the focus is changing to utility-scale projects.

“When we first came into the market, we produced 500-KW power modules,” Skibinski says. “Then we multiplied up over the years to produce an inverter that

Control Freaks Beale says the focus on the technological side of the inverter market has been increasing efficiencies.

“If you’re not at 98% or higher these days, you’re not competitive,” Beale says. “That’s becoming increasingly important to engineering, procurement and construction firms (EPCs) as they’re looking to price projects.”

Efficiencies are improving for two main reasons, says Chris

• • The rising rate of solar installations has put pressure on inverter manufacturers. They are focusing on building more powerful,

efficient and standardized products. www.solarpowerworldonline.com

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Thompson, solar business unit manager for Cleveland-based Eaton Corp. The power semiconductor components and the topologies of inverter have gotten better, leading to overall improvements in inverter technology.

“The industry has evolved from small businesses to one where global manufacturers are delivering innovations and establishing a new standard of reliability,” Thompson says. “As the industry overall scales up, the focus on process controls tightens, and expectations of equipment reliability increase.”

Since the efficiencies are becoming increasingly standardized, a differentiation point for many companies is the control software that comes with the systems.

“The demand in this market is for increasingly sophisticated control systems,” says Phil Vyhanek, president of Lawrence, Mass.-based Solectria Renewables. “Three or four years ago, people would largely trust that the system was working. Now I’m seeing far more emphasis on monitoring systems to make sure they do.”

Vyhanek says EPCs and other customers, particularly for any decently sized system, are requiring real-time information on consistency of performance.

“It used to be that the scrutiny stopped

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at the panels,” Vyhanek says. “Now there’s a lot more scrutiny placed on the inverter companies. People look at your experience, history and the quality of systems.”

Thompson concurs.

“Organizations are expecting inverters to last 10 to 20 years,” he says. “They’re asking who’s going to be there if equipment needs to be serviced 10 or 15 years from now. It’s no longer sufficient to lean on past experience.

In general, organizations are looking for longterm performance and support for decades to come.”

Advanced Energy’s Levy says investors and customers are looking for companies to provide systems that can sustain efficiency, landed costs and energy harvest over time.

“We have customers ask us all the time: ‘What’s the predictability of your systems?’”

Levy says. “They’re taking all that into account as they do their risk-mitigation assessments. They want to make sure the inverters are going to deliver the energy as promised.”

If the inverter industry does this right, inverters are going to create much more stability in the grid, which will take solar adoption to heights unseen today, Levy says. “That’s where we — and the rest of the industry — want to go,” he adds.

Standard Operating Procedures Solectria’s Vyhanek says there are at least three separate standards inverter companies have to manufacture to: Underwriter Laboratories (UL); IEEE; and The SunSpec Alliance.

“The key to knowing what you have to produce is constant communication with the governing bodies,” Vyhanek says. “You have to realize that the United States is made up of hundreds of different utilities that have slightly different standards. On top of that, you’re dealing with European listings. Bottom line? You have to customize inverter units to each job.”

AETI’s Skibinski says the utilities are much more strict about what tests they’ll accept.

“Most of our utility partners are insisting on third-party testing,” Skibinski says.

“Otherwise, they won’t be approved by the utility.”

Other testing standards out there, such as the California Energy Commission (CEC) and CSA International will test products and give companies ratings, REFUsol’s Beale says — but those ratings don’t mean anything for manufacturers doing business overseas.

“Right now, those ratings apply to North America only,” Beale says. “We wish there were more international standards. Maybe

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With too many suppliers and not enough projects, experts predict the solar inverter industry will see consolidations in the next few years.

we’ll get there someday.”

Future Trends According to Skibinski, the inverter industry is headed toward consolidation.

“There’s going to be a lot of shakeout,” Skibinski says. “There are too many suppliers and not enough projects. If you’re not a diversified company, you’re going to have sustainability problems. I expect significant consolidation to happen within five years.”

Advanced Energy’s Levy says his company is including operations and maintenance (O&M) into their business model to ensure

its customers have end-to-end lifecycle support for their power generation needs.

“You have to think big picture,” Levy says.

“We believe this is the next frontier that inverter companies will have to conquer, and we want to be on the frontline of those developments.”

Solectria’s Vyhanek says he believes the future for the inverter industry is bright in 2012 — and beyond.

“There’s a lot more scrutiny placed on inverter companies today than in the past,” Vyhanek says. “The industry is maturing and getting more sophisticated. Inverter

manufacturers are going to have to rise to that challenge — and that means improving our products to meet those higher expectations — and we’re in the process of doing so.” SPW

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SEGIS Vision and Objective The SEGIS Program Concept Paper outlines the following vision and primary objective for the program:

Vision: The Solar Energy Grid Integration Systems (SEGIS) concept will be key to achieving high penetration of photovoltaic (PV) systems into the utility grid. Advanced, integrated inverter/controllers will be the enabling technology to maximize the benefits of residential and commercial solar energy systems, both to the systems’ owners and to the utility distribution network as a whole. The value of the energy provided by these solar systems will increase through advanced communication interfaces and controls, while the reliability of electrical service, both for solar and non-solar customers, will also increase.

Program Objective: The objective of this program is to develop the technologies for increasing the penetration of PV into the utility grid while maintaining or improving the power quality and the reliability of the utility grid. Highly integrated, innovative, advanced inverters and associated balance-of-system (BOS) elements for residential and commercial solar energy applications will be the key critical components developed in the effort.

Advanced integrated inverters/controllers may incorporate energy management functions and/or may communicate with stand-alone energy management systems as well with utility energy portals, such as smart metering systems.

Products will be developed for the utility grid of today, which was designed for one-way power flow, for intermediate grid scenarios, and for the grid of tomorrow, which will seamlessly accommodate two-way power flows as required by wide-scale deployment of solar and other distributed resources.

Source: U.S. Department of Energy Solar Energy Technologies Program SPW

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Laying the Foundation for the

Grid-Tied Smart Inverter

of the Future

[

M e s a S c h a r f / D ir e c to r o f S o l u tio n s En g in e e r in g a n d Mich a e l M i l l s-Pri ce / AE Co n t ro l S o l u tio n s En g in e e r in g M a n a g e r M e m b e r o f Te c h n ic a l S taf f Sc harf

In the next 10 years, the electric grid will change more

than it has in the past fifty. Some utilities are already embracing the new smart grid; others are clinging to the status quo, believing if it isn’t broke, don’t fix it. But whether driven by mandates or market forces — or both — the migration toward a more intelligent grid infrastructure is inevitable for all electric utilities.

The primary driving force is the Renewable Portfolio Standard (RPS), which a growing number of states are adopting to set target percentages and dates for the integration of renewable sources of energy. The impact on the grid of large-scale intermittent distributed energy resources like wind and solar will be profound, forcing the grid to transition from a one-way source of power distribution to an intelligent, multi-directional infrastructure. Society and utilities both stand to benefit in many ways long-term as the percentage of renewable sources grows, although achieving these benefits will require overcoming some challenges.

In its Renewable Systems Interconnection Technical Report, the U.S. Department of Energy (DoE) states: “Now is the time

to plan for the integration of significant quantities of distributed renewable energy into the electricity grid. Concerns about energy independence, climate change, the adoption of state-level renewable portfolio standards and incentives, and accelerated cost reductions are driving steep growth in U.S. renewable energy technologies. The number of distributed solar photovoltaic (PV) installations, in particular, is growing rapidly. As distributed PV and other renewable energy technologies mature, they can provide a significant share of our nation’s electricity demand. However, as their market share grows, concerns about potential effects on the stability and operation of the electricity grid may create barriers to their future expansion.”

To address the challenges presented by high penetrations of distributed PV power generation, the DoE created the Solar Energy Grid Integration System (SEGIS) program (see sidebar.) The challenges of

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Case Study: Portland General Electric Portland General Electric (PGE) is a fully integrated electric utility that was established in 1889. Today PGE has a 4,000 squaremile service area with a population of some 1,663,000 people and more than 818,000 residential, commercial and industrial customers, making it Oregon’s largest electric utility.

PGE’s peak load has exceeded 4,000 MW, and the utility now has over 12 MW of solar capacity, three-fourths of which is customer-owned.

PGE earned a Solar Business Achievement Award from the Solar Electric Power Association (SEPA) for being the first utility in the nation to develop a unique third-party ownership model (a “turn-key” solar energy engineering, procurement and construction, or EPC, consortium) to help develop large-scale solar projects throughout its service area.

In a green state like Oregon, it should come as no surprise that the largest electric utility, PGE, now generates over 10% of its electricity with renewable resources. Such an aggressive posture puts the utility well on its way to meeting the Oregon Department of Energy’s Renewable Portfolio Standard of 25% by 2025.

Although most of the utility’s renewable capacity is currently in wind energy, PGE already ranks eighth in the nation for total solar capacity, according to the Solar Energy Power Association (SEPA). As a pioneer in distributed, renewable energy resources, PGE knew it would eventually face some challenges integrating wind and solar power. “What we didn’t know, is just how soon we would need to tackle these challenges,” says Mark Osborn, PGE’s Distributed Resources Manager.

Osborn attributes the rapid growth in solar power to a convergence of several factors, including the state’s aggressive renewable energy standard, generous federal and state grants and tax credits, the emergence of new business models for both utility and customerowned generating facilities, and the continual decline in the cost of PV power. Osborn also notes the growing risks posed by coal-fired plants with the likelihood of future restrictions or taxes being imposed on carbon emissions.

Rather than resist the inevitable, PGE is taking a leadership position by fully embracing PV power. (continued on page 33)

E NG I NE E RI NG T E CHNO L O G Y D E V E L O P M E N T S

integrating renewable energy sources are becoming familiar to many utilities as the percentage of intermittent generation, such as solar and wind, continues to increase over traditional power sources. One of the biggest challenges with photovoltaic power is the existing requirement in the IEEE 1547 and UL1741 standards for inverters to disconnect from the grid at the first sign of instability, which limits the inverter’s ability to help stabilize the grid. As the penetration of PV power production increases, such behavior threatens to undermine grid stability and the real potential of this important renewable source of energy. With smarter inverters capable of contributing to grid stability, utilities stand to gain the monitoring and control they need to successfully integrate PV power on a large-scale, distributed basis.

Art for Smart Inverters Advanced Energy’s SEGIS program addressed both economic and technical challenges involving the inverters used in PV power generation. The material in this section is, therefore, divided into these two respective areas: 1. Energy Economics, which covers the five advances that have the greatest impact on lowering the Levelized Cost of Energy for photovoltaic power generation; and 2. Utility Systems Integration, which covers three technological advances that together complete the foundation for a smart grid-tied inverter.

The focus on inverters here is not meant to downplay the importance of solar panels and other balance of system components in the economics and technology of photovoltaic power generation. Its emphasis is, rather, a recognition of the key role the inverter will play as a smart interface to the utility’s smart grid. As such, the smart inverter has paramount importance to a utility’s ability to successfully integrate distributed PV power generation on a large scale.

Energy Economics SEGIS is part of the DoE’s Solar America 32

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Initiative (SAI) that has a goal to make PV power cost-competitive with other sources of energy by 2015. Lowering the Levelized Cost of Energy (LCOE) by reducing lifetime PV system costs and increasing overall PV performance are, therefore, also goals of SEGIS. Five such advances are highlighted here.

• Improving Inverter Reliability Objective: Enable more dependable production of photovoltaic power by minimizing disruptive and costly failures in the inverter.

Historically, inverters have been one of the least reliable components in a solar power generation system. The reason is understandable: Harsh environmental conditions place tremendous stress on this piece of electronic equipment. Traditional hydroelectric, nuclear, and coal- or gasfired power plants typically reside in a controlled environment. By contrast, most components of a solar PV power plant are directly exposed to the outside environment, subjecting them to temperature fluctuations and extremes, humidity, corrosive elements, dust and other environmental stresses that are influenced by the geographic location of the installation and which must be factored into any reliability analysis.

Advanced Energy’s work under the SEGIS program has, therefore, built on the existing industry-recognized advances the company has made in the field of inverter reliability.

Advanced Energy has designed commercial and utility-scale inverters from the ground up for maximum reliability and uptime with improvements at the component, sub-system and system levels, and extensive quality control measures are used during the manufacturing processes. Rigorous stresstesting with root-cause analysis during the design phase yielded the greatest gains in long-term reliability, while redundant Smart Air Management cooling features help extend the service life of the inverters.

To accurately predict component stresses and associated wear-out mechanisms that solar inverters experience due to natural

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(continued from page 32) “Most utilities look at distributed solar as just negative load,” Osborn explains. “We view solar as the future of renewable energy and are aggressively pursuing its adoption under several initiatives.”

Among those initiatives is the partnership with Advanced Energy under the SEGIS program.

Under this initiative, PGE installed an enhanced prototype of a PV-powered inverter in a smart islanding demonstration along the Oregon Solar Highway that uses measurements from synchrophasors manufactured by Schweitzer Engineering Labs.

The Solar Highway, the first of its kind in the United States, is a PV proof-of-concept demonstration conducted by a collaboration of PGE, U.S. Bank and the Oregon Department of Transportation (ODOT). The more than 100-KW system contains about 8,000 square feet of solar panels extending about the length of two football fields along the right-of-way at the interchange of Interstate 5 and Highway 205 in Tualatin, a suburb of Portland. The state, through the leadership of its governor, has plans to build the world’s largest solar highway with a total capacity exceeding 3 MW. During the SEGIS demonstration project, PGE evaluated different techniques for overcoming challenges in two key areas: unintentional islanding and grid instability, particularly when caused by voltage/frequency sags.

According to Osborn: “We’ve found that inverters are rather benign when generating below 15 percent of the load on any distribution feeder. But as the percentage approaches 30, there can be significant problems if the utility fails to implement some means of monitoring and control.”

A particular problem PGE wanted to solve results from the now common practice of inverters disconnecting during a voltage or frequency sag.

“Sags usually occur during periods of peak demand, just when PV power is normally needed the most,” Osborn notes.

“Two-way communications with the inverters, combined with constant measurements from the synchrophasors, enables us to use the inverters to mitigate against sags and flicker much more effectively.”

The two-way communications also enable PGE to remotely disconnect and reconnect the inverters.

PGE explored two other advancements throughout the SEGIS program: using inverters to export VAr power and integration with the utility’s GenOnSys distributed generation and demand response control system. GenOnSys, which was custom-developed by PGE, is the first such application to implement the International Electrotechnical Commission’s new distributed resources standard (IEC 61850- 7-420).

“The goal with GenOnSys is to make solar power more dispatchable by treating all inverters, whether owned by PGE or our customers, as a sort of ‘virtual power plant’ possessing significant capacity,” Osborn says. “With this approach, largescale, distributed PV power can become more of an asset than a problem.”

cycles, a complex time-dependent modeling approach is required.

Because temperature cycling contributes to device wear-out, simpler constant hazard rate and MTBF calculations that might apply in other situations are not accurate in this case. Advanced Energy has created a set of time-dependent prediction tools and analytical methods to predict real-world inverter reliability with much greater accuracy and granularity than the simpler methods commonly used today.

The result of these efforts is the industry’s first 20-year warranty offered as an option on all commercial Advanced Energy inverters.

Continual improvements in reliability, combined with the advances made under the SEGIS program, may enable Advanced Energy to extend the warranty to 25 or 30 years, further lowering LCOE for PV power generation.

• Increasing Energy Harvest Objective: Demonstrate and quantify possible energy harvest improvements, under both static and dynamic irradiance conditions, with Maximum Power Point Tracking (MPPT) algorithms optimized for specific solar module types.

Although MPPT functionality is fundamental to inverter technology, its greatest contribution is ultimately economic. Inefficient solar power generation increases LCOE, and further improvements are necessary to achieve PV power parity on the grid. The situation is further complicated by the lack of universally accepted Maximum Power Point (MPP) efficiency testing standards.

Under the SEGIS program, Advanced Energy pursued two developments. The first was a proposed MPP testing plan, which weights static and dynamic irradiance and temperature conditions equally, quantifying the efficiency of the inverter to track the MPP of the connected solar panel array. As an essential metric for total energy harvest, the proposed testing matrix takes into account observed energy harvest of the total PV system. Conversion efficiency is also a vital metric in the planning, development and even the rebate structures of PV installations. But current metrics fail to reflect the contribution of MPP efficiency to the overall efficiency of the inverter system and, ultimately, to the actual energy harvest of the PV power system. The proposed testing methodology allows for third-party measurements to qualify MPP performance of inverter manufacturers as part of a standard listing. The end result is a set of efficiency numbers (much like the California Energy Commission’s efficiency number) quantifying both static and dynamic performance that more accurately quantifies the ability of the inverter to harvest energy from the solar panel arrays.

The second development effort was intended to produce a set of MPPT algorithms optimized for different commercially available types of solar modules. The different fill factors, temperature and irradiance effects, as well as settling times for different solar modules, are driving the need to improve energy harvest algorithms and otherwise maximize the total energy harvest from each type of module. The algorithms developed allow the inverter to be

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customized to the specific module type, enabling it to perform optimally with commercially available solar module panels.

The solar module technologies specifically included in these design experiments were: crystalline silicon, thin-film silicon, copper indium gallium arsenide (CIGS) and cadmium telluride (CdTe), including in concentrated photovoltaic (CVP) and tracking configurations. The effort also included incorporating enhancements being made to DC-side intelligence (DC boost) and functionality at the string- and subarray-level that contribute to increased energy harvest

• Enhance Balance of System Monitoring and Performance Objective: Development of string and zone monitoring and control solutions capable of improving overall system uptime and performance.

While string-level monitoring could contribute substantially to improving overall PV energy harvest, the technology has proven to be difficult to integrate cost-effectively into the PV control system. As a result, its use has been limited. An effective but less expensive approach is needed to lower LCOE for distributed PV power.

This effort builds on Advanced Energy’s existing IntelliString line of smart string combiner boxes. IntelliString’s performance monitoring at the string level enables more rapid and accurate diagnosis of PV system underperformance as a result of failed modules, shading or soiling. Enhancements under the SEGIS program for inverterintegrated string and zone combiner monitoring are expected to further reduce downtime and, thereby, improve system performance and lower total lifetime costs. To maximize the benefit, these enhancements are tightly integrated with the existing inverter monitoring and control system that continuously measures and records its power output.

• Improve Solar Power Forecasting Objective: Use forecasting and other techniques to minimize problems caused 34

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by the adverse effects of irradiance transients, which “While string-level monitoring are currently a barrier to effective short and long-term could contribute to improving planning for integration of distributed photovoltaic overall PV energy harvest, the power resources.

Rapid changes in cloud technology has proven to be very cover create intense power transients that can shorten difficult to integrate cost the life of switch gear and distort power quality effectively.” and stability at the host facility and in the utility grid. The transients also make it difficult for power producers, energy traders, utility dispatchers and commercial users to effectively match PV foundation that enables inverters to produce power generation to electrical demand. more stable power and avoid faults that can This Advanced Energy effort under the occur during and after cloud transients.

SEGIS program leveraged a partnership with Northern Plains Power Technologies (NPPT) • Integration with Building Energy to pursue enhancements at two levels: Management Systems Objective: Ensure that inverters can 1. utility level with the use of long-term interoperate with leading building energy irradiance forecasting to enable more management systems using advanced energy accurate predictions for optimal integration control algorithms to minimize energy into utility planning processes; and utilization and costs, and maximize return 2. inverter level with the use of realon investment (ROI). time satellite imagery on cloud position, Under the SEGIS program, the term movement and transparency to soften “Energy Management System” refers to the weather-induced transients. customer’s control over its use of energy and not to the utility’s EMS. As such, it involves Integrating weather awareness into the participation of the inverter in demandthe inverter control system is the most side management, potentially during promising approach for reducing the adverse islanding. effects of cloud position, movement and Integration with building energy transparency. When coupled with the ability management systems simplifies and of the inverter to curtail output power reduces the cost of managing commercialusing pre-defined ramping functions, the scale PV, while unlocking opportunities result is a reduction of the duty factors on to use PV more effectively as part of a tap changers and other voltage regulation comprehensive energy management strategy. equipment. This effect is more recognizable The integration effort leverages standard on feeders with higher penetrations of modbus communications over both RS485 PV power generation. Further, as a future and TCP to ensure interoperability for metric, the inverter’s ability to foresee cloud basic monitoring of and optional advanced transients will allow for more seamless control over inverter’s energy production. integration of energy storage capabilities.

Integration of the controls, communications These enhancements are laying the and safety features of the PV plant into the www.solarpowerworldonline.com

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building EMS system sets the foundation for future optimization of energy usage, including a path toward reliable, integrated on-site storage. This effort involved popular energy management systems from Johnson Controls, Delta, Tridium and Echelon.

Utility System Integration Many of the challenges to integration of distributed PV power generation on a large scale remain technical. For this reason, the primary objective of SEGIS was “to develop the technologies for increasing the penetration of PV into the utility grid while maintaining or improving the power quality and the reliability of the utility grid.” Three such advances are part of Advanced Energy’s efforts under the SEGIS program.

• Real-time, Two-Way Utility Communications and Control Objective: Leverage existing and emerging communications technologies, including Advanced Metering Infrastructure (AMI) and others, which already do or will cover utility service areas to enable real-time, twoway communications with and control of distributed smart inverters.

Utilities today are unable to exert significant control over inverters, especially those owned by their customers. Anticipated changes to regulations, which now prohibit such control in most situations, are beginning to clear the way for numerous advancements in this area.

Advanced Energy worked with multiple utilities during the SEGIS program to develop solutions that enabled advanced controls over differing communication media.

As the intelligent node in solar electric power generation, a utility’s ability to communicate with and exert control over distributed inverters facilitates effective integration of high-penetration PV power generation into the grid. These control capabilities include ramp rate, curtailment, power factor (volts-amp reactive support) and on/off functionality. The ability to remotely control an inverter’s output 36

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characteristics minimizes the adverse impacts of solar power as an intermittent source of energy. The additional ability of a utility to treat distributed generation as an aggregate resource to improve power quality and regulate voltage on the grid facilitates PV penetration rates that can far exceed what is feasible today. This real-time, two way communications capability, coupled with a base-line set of controls, has laid a framework for a new set of interactive Smart Grid support features for the utility.

• Smart Islanding Detection and Power Quality Enhancements Objective: Develop more intelligent intentional islanding techniques that can enhance power delivery and quality in high-penetration PV scenarios, while still ensuring the safety of utility personnel.

Currently, most inverters cannot differentiate between a true utility outage (when an anti-islanding disconnect is required) and a grid disturbance or brownout situation during which the PV system could actually assist in supporting the electrical grid. Even for those inverters that can differentiate between these two different conditions in many or most situations, current regulations (IEEE1547/UL1741) require the inverter to disconnect from the grid. In addition, many inverters now use a disruptive “perturb and observe” technique to determine if the grid is still connected, which may further degrade power quality, especially in high-penetration scenarios.

Finally, interactions between inverters from different manufacturers may result in false island detection and increased run-on times that compromise the safety of utility line personnel.

To address these issues, Advanced Energy is working closely with Schweitzer Engineering Laboratories (SEL) and NPPT on Smart Islanding Detection. Smart Islanding Detection is an enhancement intended to better distinguish between a true island condition and a voltage or frequency disturbance that could benefit from additional power generation by the inverter.

The approach employs synchrophasor measurements to enable the inverter to detect both conditions more accurately. The synchrophasor measurements are taken at different locations in the power system, and then compared to provide a precise and reliable method of determining the state of the utility at the point of inverter interconnection.

The use of synchrophasor measurements for island detection has many near-term benefits. These include reducing power quality problems caused by taking active and intrusive “perturb and observe” measurements, and eliminating the potential for increased run-on time in installations with multiple inverters.

The use of synchrophasors has also shown to be extremely reliable in detecting islanding events on those inverter installations that are coupled with synchronous generators, motors and other adverse loads on the same feeder line without subjecting it to false trips.

With the development of the synchrophasor-based islanding technique, it has become feasible to use the synchrophasor measurements throughout the grid to implement other grid support and power quality enhancements. For example, intentional islanding for microgrid partitioning is being investigated and shows promising results, as the islands can be synchronized before re-connection, allowing for loaded islands to be re-energized from a live feed with minimal current surging. Adaptive volts-amp reactive (VAr) compensation techniques are also being investigated that will allow for “self-healing” grid characteristics and improved power delivery to customers.

In addition, the knowledge of upstream voltage and current enables the inverter to make changes in its control paradigm to improve power quality, regulate voltage and improve grid stability throughout the feeder line, without compromising the safety-critical island detection. Finally, synchrophasor-based island detection eliminates the safety concerns associated

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with multiple inverter cross-talk, inverterto-generator cross- talk, and feeder lines that have unusual load/generation characteristics.

With the assistance of synchrophasorbased measurements, further enhancements to inverter operation and grid stability have become possible, further laying the foundation for a smart grid compatible inverter system.

• Distributed and Hierarchical Smart Inverter Management Objective: Integrate the advancements described above to afford utilities with unprecedented capabilities for managing distributed photovoltaic power generation.

To fully and successfully integrate high penetrations of renewable energy sources, utilities need better visibility into and control over these resources. Such control is virtually impossible today with the lack of standards and certain regulatory restrictions.

Advanced Energy’s work under the SEGIS program, therefore, involved both making advances in smart inverter management and coordinating those advances with the pertinent standards bodies.

This aspect of the SEGIS program builds on both existing management capabilities in Advanced Energy’s inverters and the other technology advances being made in the program. The real-time, two-way communications and control capabilities are obviously fundamental to a distributed and hierarchical smart inverter management system. So too are the Smart Islanding Detection and power quality enhancements that together help enable the inverter to contribute to grid stability. These and other advances constitute the flexible communications and control platform that was needed to interoperate with both the electrical grid of today and the smart grid of the future.

Although the “intelligent” or smart inverter management ecosystem is still evolving, some of the essential requirements utilities have for exerting direct control are already apparent. These include (in no particular order): automatic discovery with

unique identification; power production monitoring; event data logging; time synchronization; remote on/off control; remote software updating; and power quality scheduling and control (including for storage). Additional capabilities will also be needed, of course, to afford full control over the inverter, and its prominent role in monitoring and managing other balance of system components.

The best and most likely management scenario for distributed generation is a corresponding distributed hierarchy. Under this hierarchy, smart inverters would be monitored and controlled centrally by the utility, either directly or through another system, such as a plant controller. Direct management is likely with individual or master/slave configurations of commercial and residential inverters. A hierarchy of control is likely to exist with large-scale PV power generation facilities, as well as where multiple sources of distributed generation are aggregated into a “virtual power plant”.

Advanced Energy is actively participating with standards organizations to ensure interoperability for the advancements being made under the SEGIS program and elsewhere. These organizations include the National Institute of Standards and Technology (NIST), the Institute of Electrical and Electronics Engineers (IEEE), the Electric Power Research Institute (EPRI) and the SunSpec Alliance. Advanced Energy is also monitoring other organizations for potential activity involving smart inverter management.

The combination of improving the economics of PV power and laying a full foundation for the management of smart inverters by utilities, the SEGIS program and Advanced Energy’s leadership role in it are accelerating the adoption of distributed renewable sources of energy and helping to put PV’s LCOE on the path to parity with traditional sources of electrical energy.

Conclusion By the year 2020, the electric grid will have undergone a remarkable transformation. www.solarpowerworldonline.com

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PGE and many other utilities will be getting 20% or more of their power from renewable sources of energy. Key to this promising future is the performance and inter-operability of the smart inverter. The smart inverter is to the smart grid what the router is to the Internet: an intelligent device designed for coordinated, end-to-end control in a distributed environment. The result will be a more resilient and stable grid with better prediction of and management over widespread PV power generation from both utilities and their customers. Improvements in forecasting and integration of energy storage options will make it possible to better match supply with demand. Microgrids and their energy management systems will benefit from more intelligent islanding capabilities. And enhanced energy harvest and improved reliability, combined with continual declines in the cost of PV panels, will put the LCOE of solar on a par with other sources. SPW Scharf is the director of solutions engineering, and Mills-Price is PE Control Solutions Engineering Manager Member of Technical Staff, for Advanced Energy.

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This gasket incorporates a ceramic-based sealing material to withstand molten salts in CSP plants.

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How To

Seal Molten Salts In Concentrated Solar Plants

S h e rwi n Da m d a r / S e n io r P r o d u c t En g in e e r a n d Wa y n e Ev a n s / P r o d u c t D evelopm ent Engi neer/ Ga rl o ck S e a l i ng Te c h n o l o g ie s

Solar power will undoubtedly be a key component in most countries’ energy portfolios as the world turns to more renewable resources. But the cost of solar energy – it is still considerably more expensive than fossil fuels — will remain an impediment to rapid, widespread commercialization until concentrated solar power plants become more efficient.

One way to do this is by using hotter heat transfer media, which is generating considerable interest in molten salts. The use of this medium requires developers to convert from traditional graphite-based sealing to ceramic-based solutions due to the temperature limitations of graphite. Once the sealing material of choice for high-temperature applications, graphite is being replaced by a new generation of advanced materials that can seal molten salt systems more effectively.

Concentrated solar power (CSP) systems employ mirrors or lenses to concentrate sunlight onto small areas where it is converted to heat to drive an engine linked to a power generator. www.solarpowerworldonline.com

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Like conventional fossil fuel plants, CSP plants utilize large turbines turned by steam to generate electricity. The only difference is the source of heat for boiling the water. Its simplicity and the fact that little to no rare earth minerals are required in its manufacture make CSP technology attractive to many solar developers, especially in light of environmental concerns.

There are three basic types of CSP systems — linear dish concentrators, dish engines and power tower systems. Linear dish concentrators consist of parabolic reflectors that concentrate light onto receiver tubes positioned along their focal lines and filled with a heat transfer medium.

Dish engines use a stand-alone parabolic reflector that concentrates light onto a receiver at its focal point, where a transfer fluid is heated. Solar power 5 • 2012

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towers employ an array of dual-axis tracking reflectors that concentrate light onto a central tower-mounted receiver containing a heat transfer medium.

These collection systems are often supplemented by thermal storage systems from which transfer fluid can be drawn when heat from the sun is not being harvested. Using molten salts for thermal storage allows electricity to be generated even when the sun is not shining for more even production levels.

This facilitates pricing and allows production to be increased during periods of heavy demand.

Moreover, continuous operation is easier on the overall system; fewer startups and shutdowns reduce operating expenses, both from an equipment and labor standpoint.

Heat Transfer Fluids Many CSP plants use synthetic oil as the heat transfer fluid.

These oils are highly flammable, and their maximum operating temperature is 393°C. Molten salts, by contrast, can be used at operating temperatures in excess of 500°C, improving plant efficiency and lowering the cost of power generated.

There are a number of components in CSP plants that require sealing, including valves, flanges, pumps, piping, joints and reflector connections.

Traditionally graphite has been used to seal systems using synthetic oils. Unfortunately, it begins to lose mass at elevated temperatures in oxidizing environments. Graphite is typically recommended for sealing applications up to 454°C, above the maximum for synthetic oils, but well below that for molten salts. Above this temperature, carbon in the graphite combines with oxygen from the air to produce CO and CO2 , causing it to literally dissipate into the atmosphere. The rate of oxidation varies with the temperature and amount of oxygen to which the seal is exposed.

Ceramic-based sealing solutions To find a solution for effectively sealing highly

Inspection of the pressure vessel confirmed the new gasketing completely stopped the leakage of molten salts.

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effects of the molten salts on sealability, which made it possible to identify the optimal formulation.

In addition to these quantitative results, the gaskets were inspected visually after the pressure vessel was disassembled to determine if the molten salts had penetrated them.

The Kammprofile and sheet gaskets were also successfully tested in a molten salt valve per the below procedure:

Pressure vessel was tested with and without molten salts to evaluate the performance of the ceramic gaskets at 500 C and 30 psi.

oxidizing media like molten salts, a number of prototype ceramicbased gaskets were developed in Kammprofile, spiral wound and compressible sheet form. These gaskets were tested for their ability to withstand molten salts at elevated temperatures. Figure 1 depicts a metal-reinforced Kammprofile gasket with a ceramic sealing element.

The testing apparatus included a pressure vessel for the molten salts, oven, compressed air supply and leak measurement device. The pressure vessel was fitted with a pair of 2 in., 300-lb blind flanges, one of which was modified to allow fluid to be piped into it.

Next, the piping was extended to the oven and connected to the compressed air supply and a leak measurement device (30 in. mercury manometer) to read the pressure. The temperature of the pressure vessel was limited only by the capability of the oven. In some cases, the gaskets were subjected to elevated temperatures for as little as two hours, in others as long as a week.

The objective of the test was to compare the leakage rates of various ceramic-based sealing materials. The data showed the

1. Valve and HiTec solar salt heated to 300˚C and valve exposed to seal.

2. Salt and valve temperature increased to 500˚C. 3. System pressurized to 15 psig.

3.1. Valve actuated through 10 open/close cycles 4. System pressurized to 50 psig 4.1. Valve actuated through 10 open/close cycles.

5. Pressure increased in 50 psig increments to a maximum of 250 psig.

5.1. Valve actuated through 10 open/close cycles at each pressure.

6. System salt maintained at 500˚C for 24 hours.

6.1. Valve actuated until failure.

Conclusion It is estimated that concentrated solar power could account for up to 25% of the world’s energy needs by 2050 as advances in the technology make it increasingly viable. Key to that viability is the ability to effectively seal high-temperature heat transfer media, allowing developers to improve plant efficiency and drive down the cost of solar power. SPW

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Out of the

Incubator Under the wings of a business support system, Pythagoras Solar emerged with breakthrough BIPV technology.

Fr a n k A n d o r k a / Ed ito r ia l D ir e c to r

T

he list of what the land of Israel has bestowed upon the world is virtually immeasurable.

It is the birthplace of three monotheistic religions (Christianity, Judaism and Islam) and has provided some of the greatest politicians and diplomats the world has ever known (Abba Eban, Golda Meir and Menachem Begin). What is less known (at least outside of its own borders) about the country is that it is also a hotbed for technological innovation.

In 1991, the state of Israel’s Ministry of Industry, Trade and Labor launched the Technological Incubators program, whose express purpose was “to transform innovative technological ideas that are too risky and in too early stage for private investments into viable startup companies that, after the incubator term, are able to raise money from the private sector and operate on their own.”

From one such incubator program came a company called Pythagoras Solar, a manufacturer of building integrated PV (BIPV) panels that, through the vision of founders Dr. Itay Baruchi, an award-winning physicist, and Gonen Fink, a leader in taking Check Point Software from startup to a multibillion dollar company, saw an opportunity to develop a new kind of BIPV.

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T E C H N O L O G Y

D E V E L O P E R S

How It Came To Be Brendan Dillon, director of product marketing for Pythagoras Solar, said the initial impetus for the company’s Photovoltaic Glass Unit (PVGU) was that the founders understood that for solar to be a serious energy option for Israel, it would have to move beyond building solar farms in the desert.

“They realized pretty early on that distributed solar energy was going to be the wave of the future,” Dillon says. “So they started looking at different information about the solar industry and devised a plan to accelerate its development.”

Dillon says Baruchi and Fink came up with some prototypes for transparent solar panels. It was through trial and error that they came to develop the PVGU, which were designed around the basic elements of a double-paned window. Baruchi and Fink decided the product had to have three critical attributes before it could be commercially viable:

•It had to replace a more traditional building product; •It had to generate electricity; and

•It needed to be aesthetically pleasing enough for architects to be willing to specify the product as part of their original designs.

How They Work According to the company’s website, the first Pythagoras Solar PVGU products were designed for vertical curtain walls and skylight applications. They can also be optimized for elevation, location and climate zone through Pythagoras’ proprietary software tools.

Dillon says the product is two separate pieces of glass separated by air, PV tiles, optics systems and prisms attached to the solar cells (see diagram). Pythagoras produces 5 ft. by 5 ft. windows that are then sold to glazing companies.

The glazed windows are used in curtain and two insulated negative leads come out of each unit. The leads are attached to the same balance-of-systems (BOS) and inverters that are used with other systems. Windows are then connected in parallel and attached to inverters on the roof or in a closet.

“The way these windows are built basically doubles the efficiency of the cells,” Dillon says. “It also blocks the light from going into the building, which immediately

makes the buildings more energy efficient.

Pilot Installations Pythagoras started pilot installations in 2010 with three buildings in Israel and the Sears Tower in Chicago. The company completed the first installation at the Sears Tower two months ago. The owner was developing a program and examined a number of different technologies.

“We were the first technology deployed in a small installation on the 56th floor,” Dillon says. “It validated a lot of the claims we were making.”

Dillon says the project will take a few years to put together. Pythagoras will be working closely with the developers so when the project really takes off, it can be there to support them.

“We’ve had a good response from the architects around the world,” Dillon says.

“For many architects, solar PV doesn’t make any sense economically or aesthetically.

Most architects see this product and think immediately about how they can use it for different parts of the building.”

Dillon says the company is working on projects this year and moving into 2013. SPW

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September 10 –13, 2012 Orange County Convention Center Orlando, Florida www.solarpowerinternational.com

Generating Business The solar energy industry is in high gear, and it’s time for you to grow with it. At Solar Power International 2012, plug in to the technologies, personal connections and professional insights that give rise to new opportunity.

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[PRODUCTS ]

Modules Yield More Watts Per Square Foot Mage Solar’s Powertec Plus Modules feature high efficiency, a 30-year 80% power output guarantee and zero to +5 W tolerance for maximum power generation. The company’s newest model is a 250-W monocrystalline and a 235-W polycrystalline unit. A black monocrystalline version of the module is also available as an aesthetically pleasing alternative for dark roofs or historical renovation projects. A UL-listed, ARRA-compliant version of the new wattage-types will also be available soon.

Mage Solar USA www.magesolar.com/us/

Multi-Pin Connector Meets PV Requirements Anderson Power Products says its Solar SPEC Pak is the first multi-pin connector to meet the photovoltaic industry requirements specified in UL 6703A, passing the same harsh environmental tests used to qualify solar panels. The connector has power handling capabilities up to 1000V and features a locking latch. The connector is capable of handling up to four individual lines, which reduces the number of traditional connectors needed in solar applications, minimizing the space needed while lowering installation costs.

Anderson Power Products www.andersonpower.com

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[ PR O D U C T S ]

An Inverter With Fanless Technology Growatt, a Houston, Texas-based solar inverter manufacturer, offers its 3600MTL-US/4200MTL-US/5000MTL-US model, which has a number of innovative features including: maximum efficiency 98%, wide input voltage range, internal DC switch, transformerless H6 topology, compact design, multi MPP controller, MTL-String, bluetooth technology, sound control and easy installation.

Growatt www.growattusa.com

DC Converter Module Boosts Panel Output eIQ Energy’s Boost 600 DC-to-DC converter modules boost solar panel output to a predictable, constant voltage, while providing up to 600W of power capacity–enough to handle two crystalline silicon PV panels or multiple thin-film panels. The company’s vBoost DC Parallel System includes the converter modules, communications modules and web-based monitoring software.

Together, these enable solar panels to be wired in parallel, rather than in series. Parallel solar installation is said to have lower up-

Advanced Fastening Systems

front cost, less on-site interconnection labor and less design and

Mudge Fasteners says its DURA-CON fastening systems

installation constraints.

feature fasteners specifically tested for solar applications.

eIQ Energy, Inc. www.eiqenergy.com

Features include: saving up to 40% vs. industry-standard stainless steel, resistance to environmental corrosion, fasteners are tested at 1,500 salt spray hours in aluminum with no corrosion (ASTMB117), the fasteners avoid galvanic corrosion of aluminum caused by stainless steel, eliminate galling, create reliable clamp force and greater tensile strength than stainless steel and can be compatible with the American Recovery and Reinvestment Act.

Mudge Fasteners Inc. www.mudgefasteners.com

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[PRODUCTS ]

Metallization For Thin-Film Photovoltaics DuPont Microcircuit Materials (MCM) has introduces its Solamet PV416 photovoltaic metallization, a frontside silver paste used to raise the efficiency of thin-film photovoltaic cells. This silver enables processing at temperatures less than 140°C, and provides improved contact resistance, conductivity, adhesion and fine line resolution when printed on Transparent Conductive Oxides (TCOs)—properties for improved performance in Copper Indium Gallium (di) Selenide (CIGS), amorphous silicon (a-Si), and Organic Photovoltaic (OPV) cells and modules.

DuPont http://photovoltaics.dupont.com

Large Rooftop Solar Solution Trina Solar Limited offers its high performance 60-cell, up to 260-W Honey module series. The Honey cell features greater surface area and more efficient capture of sunlight, resulting in more power per area. Laboratory tests demonstrated that a 60 Honey cell module set a record for multicrystalline module power by reaching a 274-W peak. By combining the modules with the the company’s mounting system, Trina Solar says customers can install Trinamount Honey systems up to 4.5 times faster while, lowering installation costs by up to 10 percent.

Trina Solar Limited www.trinasolar.com

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[ PR O D U C T S ]

Flexible Solar Modules Global Solar Energy’s PowerFLEX BIPV thin-film modules are low weight (3.5 kilograms per square meter) and well-suited to industrial roofs, which are unable to bear high loads.

After being rolled onto the roof surface, they are simply affixed into position and require no support frames or stands. The roof membrane is not penetrated and no additional wind loads are produced. Each measuring 5.74 x 0.5m, the new modules have a power density of up to 300W. High module efficiencies of up to 12.6% are reached due to technology based on Copper, Indium, Gallium and diSelenide.

Global Solar Energy www.globalsolar.com

Software Simplifies Off-Grid PV An Inverter With Economic Efficiency

SMA says its Off-Grid Configurator assists with designing the ideal off-grid photovoltaic (PV) system. This software analyzes each design aspect, from sizing the PV array to preparing a final cost analysis, thereby providing comprehensive planning that saves time and reduces costs.

All results are displayed graphically and can be printed as

Siemens Industry, Inc.’s Sinvert

Microsoft Excel, Word documents, or as a PDF.

PVM UL inverter is designed for peak efficiency and maximum plant yields. The inverters run from 12 kW to 24 kW for small to medium sized plants in the

SMA America www.sma-america.com

commercial market, and are capable of delivering over 98% peak efficiency. Capable of outputs for PV plants up to the megawatt range, the inverters provide economic efficiency over the entire life cycle of a grid-connected PV system

Siemens www.usa.siemens.com

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The Industry’s Biggest Newsmakers — Now In Their Own Words

Solar Power World’s weekly podcast program ask the questions you would ask if you had the chance.

Subscribe on I-Tunes to download them automatically or check out our multimedia channels.

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[CONTRACTORS C O R N E R ]

LightWave Solar, Nashville, Tenn.

Steve Johnson, president of Nashville, Tenn.-

Steve Johnson

President L i g h t Wa v e S o l a r

based LightWave Solar, first dabbled in the solar industry back in 1982. But it took him until 2006 to launch his own company — and he hasn’t looked back.

“I always liked solar because I liked the idea of making your own electricity,” Johnson says. “Something captivated me about the whole concept. Why wouldn’t you want to do that if you could?”

LightWave Solar is the largest solar installer in Tennessee and has seen steady growth for the past three years. From 2008-2011, the company has grown 760% and added more than 30 employees.

The company covers the entire state and focuses on 90% commercial and 10% residential installations.

Tennessee was involved last month in something of a controversy over its solar industry, as the Tennessee legislature was working on a bill that would have raised taxes on the industry more than 6,000%. Fortunately, the Tennessee Solar Energy Industries Association (TenneSEIA) negotiated with the legislature to pull the legislation for the balance of 2012. The expectation

LightWave Solar Vital Statistics:

is that a compromise bill will be brought up during the 2013 legislative session.

[Editor’s Note: For Solar Power World’s coverage of this issue, check out the website at www. solarpowerworldonline.com in the blog and podcast sections.)]

Johnson, who serves as the vice president of TenneSEIA, is concerned about where the industry, which employs 6,000 in the state, is.

“It’s hard to tell, but it would be a bad idea to cut it off at this point,” Johnson says. “We have a diverse number of companies who have relocated their solar businesses here.

“But the Tennessee Valley Authority (TVA) are cutting back incentives, there are no state incentives to speak of,” he continues. “We keep making the argument that all utilities are subsidized — why not ours? Hopefully, we have enough of a market penetration to stay strong.”

Johnson does believe the public is on the side of continuing Tennessee’s explosive growth in the solar industry.

“We’d like to see it continue,” Johnson says. “People are starting to see solar as the gift that keeps on giving — and that’s good for everybody.” SPW

3-year growth:................760% 2008 Sales: ....................$1.1 million 2011 Sales: ....................$8.4 million Employees:.....................34 Founded: .......................2006 Website: www.lightwavesolar.com

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Partnering with America’s largest solar panel manufacturer allows Kohl to chase big waves and spread his passion for solar. Find out how becoming a SolarWorld Authorized Installer can help you achieve a work-life balance at

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Finally, someone beat Advanced Energy’s 97.5% CEC efficient solar inverter.

It’s the 98% efficient AE 500 NX-HE. Advanced Energy’s AE 500 NX-HE (formerly the Solaron 500 HE) inverter just achieved the industry’s highest efficiency rating on the CEC list for the third year in a row. Now we’re up to 98% weighted CEC efficiency – improving on last year’s industry record of 97.5%, and staying one to three percentage points ahead of the competition. That 98% average includes all auxiliary power so every percentage point increase in efficiency delivers an exponential return on your investment. Oh, and lastly, its peak efficiency is 98.7%, all in.

See how much you have to gain by choosing the 98% efficient AE 500 NX-HE inverter from Advanced Energy. www.advanced-energy.com/98percent sales.support@aei.com | 877.312.3832

Advanced Energy is a U.S. registered trademark of Advanced Energy Industries, Inc.

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