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Solar Energy

Generating it…and Survival Tactics with or without it.

Liesil Alderfer Arredondo World Changing Maymester 2008 Professor Douglas Klahr

A brief look into the history of solar energy: The photoelectric effect was first noted by a French physicist, Edmund Bequerel, in 1839, who found that certain materials would produce small amounts of electric current when exposed to light. In 1905, Albert Einstein described the nature of light and the photoelectric effect on which photovoltaic technology is based, for which he later won a Nobel prize in physics. The first photovoltaic module was built by Bell Laboratories in 1954. It was billed as a solar battery and was mostly just a curiosity as it was too expensive to gain widespread use. In the 1960s, the space industry began to make the first serious use of the technology to provide power aboard spacecraft. Through the space programs, the technology advanced, its reliability was established, and the cost began to decline. During the energy crisis in the 1970s, photovoltaic technology gained recognition as a source of power for non-space applications.

Source: Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.

Solar Cell

A number of solar cells electrically connected to each other and mounted in a support structure or frame is called a photovoltaic module. Modules are designed to supply electricity at a certain voltage, such as a common 12 volts system. The current produced is directly dependent on how much light strikes the module. Multiple modules can be wired together to form an array. In general, the larger the area of a module or array, the more electricity that will be produced. Photovoltaic modules and arrays produce direct-current (dc) electricity. They can be connected in both series and parallel electrical arrangements to produce any required voltage and current combination.

Today's most common PV devices use a single junction, or interface, to create an electric field within a semiconductor such as a PV cell. In a single-junction PV cell, only photons whose energy is equal to or greater than the band gap of the cell material can free an electron for an electric circuit. In other words, the photovoltaic response of single-junction cells is limited to the portion of the sun's spectrum whose energy is above the band gap of the absorbing material, and lower-energy photons are not used.

One way to get around this limitation is to use two (or more) different cells, with more than one band gap and more than one junction, to generate a voltage. These are referred to as "multijunction" cells (also called "cascade" or "tandem" cells). Multijunction devices can achieve a higher total conversion efficiency because they can convert more of the energy spectrum of light to electricity. As shown below, a multijunction device is a stack of individual single-junction cells in descending order of band gap (Eg). The top cell captures the high-energy photons and passes the rest of the photons on to be absorbed by lower-band-gap cells.

Ground Breaking Materials

Much of today's research in multijunction cells focuses on gallium arsenide as one (or all) of the component cells. Such cells have reached efficiencies of around 35% under concentrated sunlight. Other materials studied for multijunction devices have been amorphous silicon and copper indium diselenide. As an example, this multijunction device uses a top cell of gallium indium phosphide, "a tunnel junction," to aid the flow of electrons between the cells, and a bottom cell of gallium arsenide.

How Solar Works In Your Home or Business After installation, solar panels absorb the sun's rays, even on cloudy days, and convert sunlight into usable electrical energy. Next, an inverter converts the DC current from the solar panels to AC current for use throughout your home. Your solar system is connected to the utility grid through a standard utility meter that tracks your net power use while taking into account the electricity production from your solar system. During sunny days when your solar system generates more power than your home needs, your electric meter actually reverses direction and spins backwards as you lend that energy to the utility grid. When the sun goes down, you effectively retrieve that energy when you need it. This process is called net metering.

Ready Solar Solar in a box Specifications

Ready Solar’s Standardized Solar in a Box Includes: Pre-mounted, grounded, solar modules Patented Ready Solar mounting frame in bronze Inverter with integrated AC & DC disconnects & GFCI Weather-proof combiner box & connector cables Comprehensive Warranty Each 3-panel Solar in a Box unit measures 10' L x 6' W; 2 units = 1kW

Consumer needs to hire electrician to install

Each RS unit: 1/2 kW Peak Wattage (AC)


Square Feet


Weight on Roof (lbs.)


Lbs./Sq. ft.



1.5 -5kW DCAC Inverter; AC & DC disconnects

Code & Standards Compliance


for warranty to be valid.

UL1703, UL1741, IEEE 1547, NEC 2005, CEC


Contact a Ready Solar representative for pricing. Pricing does not reflect the $2000 Federal tax credit and the state or utility rebate: Customer will need to apply to receive tax credit and rebate upon confirmation of permit approval. Price does not include estimate for installation, shipping or sales tax. Sun Run 180 Montgomery Street San Francisco, CA. 94104 1-877-SUN-MOJO

Koepp-Baker Residence, Morgan Hill, CA

Gross Cost: Federal Tax Credit: Net Cost: First Year Bill Savings:

Is SunPower a Smart Decision ? With Sun Power

Without Sun Power

Monthly Loan Payment



Tax Savings *







$38,000 $2,000 $36,000 39%

Monthly Electric Bill

Monthly Net Cost

Smart, YES, but difficult for the average consumer to pay forâ&#x20AC;Ś.. Nellis Air Force Base uses SunPower to build the largest PV solar power plant in North America

When taking into account the average consumerâ&#x20AC;&#x2122;s yearly electrical usageâ&#x20AC;Ś

Environmental Benefit of a switch to solar energy: Eliminate 9,102 lbs of CO2 emissions over the first year. This is equivalent to...

Planting 0.70 acres of trees

Driving a vehicle for 10,922 miles

This is not a how-to-book; it is meant to illustrate some of the concerns of passive solar design and at the same time to tickle the imagination. It is my hope that the basics offered in this book will aid people in their efforts to design energy efficient buildings which are attuned to the environment, integrated with the landscape, beautiful to behold, and above all, in harmony with the whole of nature. Dedicated to the world around us; David Wright Environmental Architect The Sea Ranch, California

Think Thermos

Designing and implementing simple things that workâ&#x20AC;Śis the key:

Handy Hardware

Green house to cool the effects of the harsh sun before the living space begins

Air- locks are used in submarines and space vehicles to keep from losing vital support substances. Today, the energy for heating and cooling buildings is valuable, and air-locks help to retain the invested energy.

Sod Roofs… in some urban environments, animals are kept up on building roof tops… not a crazy idea if space is meager…designing roof tops that can structurally support additions, family activities, live-stock might be a necessity in the future.

Adjustable and seasonal designs make senseâ&#x20AC;Ś

Shading devices where there is no shadeâ&#x20AC;Ś

Water Harvesting Container

How to buy a container or two of your own? Contact: Warehouse address:

Jon McMillan 214.417.3464 Oak Cliff Metals 523 Pontiac Avenue Dallas, TX 75203

330 gallon tank $50

275 gallon tank $40

This stretch of roofing fills the tank in about 3 heavy rain falls.

Vines have already just naturally started to wind their way up and around the tankâ&#x20AC;Śyou could plant your own fast growing vines.