Mother Earth Living

Plugging into the Sun: Solar Energy for the Future

Photovoltaics may be the ultimate energy source for the twenty-first century.
By Joe Hurst-Wajszczuck
May/June 2002
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PV shingles and slates such as this Sunslate from Atlantis Energy Systems can take the place of conventional roofing materials and generate electricity.
Photo by Joe Coca

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In a way, all of us are already using solar power. Burning coal, oil, and natural gas to run the turbines in our power plants releases the solar energy trapped by plants millions of years ago. Unfortunately, the process also releases tons of carbon dioxide, sulfur dioxide, and nitrous oxide emissions. Mining and drilling operations further damage our environment.

In stark contrast, photovoltaic (PV) systems produce electricity with no noise, air pollution, or moving parts, and use an inexhaustible resource—the sun. According to some estimates, by 2010, PV systems will reduce carbon dioxide emissions by ten million metric tons per year by replacing fuel-burning power plants.

Bill Lord of Cape Porpoise, Maine, invested $25,000 in a 4,200-watt array for his house. His six-year-old home generates 4,100 kilowatt hours (kWh) annually—330 kWh more than he uses. “I’m happy to donate the surplus to my local utility company,” he says.

Now that recent advances in PV technology have created thin-film PV modules that can be integrated into asphalt shingles and metal roofs, solar systems are no longer as unsightly as they were, and more homeowners are considering sun power. However, think before you leap; according to Lord, solar electricity can be a “free lunch—just as long as you are willing to pay for breakfast [installation].” Here’s how you can decide if a solar system makes sense for you.

PV primer

In 1994, Subhendu Guha, executive vice president of United Solar Systems, was lecturing on the benefits of solar energy and showing a picture of solar cells arrayed on the roof of a house when an architect in the audience said, “But it’s so ugly. Who would want that on their house?” Two years later, Guha developed a solar shingle that could be nailed directly on the roof. The shingle uses a thin-film solar cell made from amorphous silicon, an environmentally safe element found in sand, applied to a sheet of stainless steel. Unlike traditional solar modules, which attach to the roof, these PV shingles are the roof. Most recently, United Solar has developed a solar film that can be easily affixed to standing-seam metal roofs. Although less efficient than earlier crystalline cells, these modules can be integrated into an asphalt roof or used instead of traditional roofing materials, and they have brought solar electricity back into the spotlight.

Is PV for me?

There are many good reasons for investing in PVs, but first you must be prepared to make some changes. According to Steve Strong, an architect who has been designing energy-autonomous homes for twenty years, solar systems can easily be integrated into new designs, but they’re much more difficult as a retrofit. “It’s important to make your home worthy of the investment,” he says. As a first step, Strong advises investing in a home energy audit to improve your home’s overall efficiency.

Next, consider your home’s location and orientation. For maximum solar gain, your solar array should be installed on a south-facing roof. “The problem is that most homes are oriented according to a zoning map, not for solar efficiency,” says Strong. He points out that houses in the Sunbelt will be candidates regardless of orientation, but that orientation becomes more important as you travel north.

Lastly, a well-designed PV system needs clear access to the sun’s rays for all or most of the day—unobstructed by trees, roof gables, chimneys, or other features. “PVs don’t like shadows,” says Strong. For example, the shadow from a flagpole creates a resistance field that will impede the entire module’s flow of power production.

A photovoltaic installer should be able to assess the viability of outfitting your home with solar array. For a rough estimate, you can check out the National Renewable Energy Lab’s PV calculator, PVWATTS (see “Resources” on page 76). The site also contains a “pollution prevention calculator” that will determine the yearly amount of pollutant release your system will prevent.

Paying for PV

Even though improved manufacturing processes have reduced the cost of photovoltaics to less than 1 percent of what they cost in the 1970s, solar electricity still costs two to five times more than electricity from the utility companies.

Determining the price of a system depends on several variables. The most significant factor in determining the total and per-watt cost of your PV system is size (see “Stepping into Solar Power,” below). For example, a seventy-five-watt single-PV-panel system with a built-in inverter can cost as little as $900 installed, or about $12 a watt. In comparison, a five-kilowatt system that can completely satisfy the electrical needs of most homes may cost $30,000 to $40,000 installed, or $6 to $8 dollars a watt. For those who choose to live completely off the grid, or who require backup power, batteries can increase the system’s cost by an additional $1.50 to $3 per watt. Although it may seem like a sizeable investment, “buying a photovoltaic system is like paying for years of electric bills up front,” explains Lord.

There are times when investing in PV can pay off immediately. For example, in remote areas, PV electricity can cost about as much as paying the local utility to bring in a new line. And because being “at the end of the line” can mean lengthy outages, using PV means that no one will be able to cut your power off.

To help defray costs, many states are now offering financial incentives, including income tax credits, property tax exemptions, state sales tax exemptions, loan programs, grant programs, and net-metering programs. A few utility programs are also offering financial incentives, such as leasing programs, rebates, low- and no-interest loans and grant programs.

Some of the best deals can be had in California. Currently, state rebates will pay up to half the cost of the PV system, and other tax incentives are offered. There is also a $750 rebate available from the California Energy Commission. California homeowners are responding enthusiastically to the incentive program. In fact, California Home Depot outlets are now selling PV kits, made by AstroPower, that are designed for do-it-yourselfers.

Investing in PV isn’t simply about saving money. As Strong points out, “Photovoltaics allow people to take control of their energy destiny. For those people who want to be technological pioneers, to fix future operating costs, and simply tread lightly on the earth, it’s their best option.”

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