Plugging into the Sun: Solar Energy for the Future

Photovoltaics may be the ultimate energy source for the twenty-first century.

| May/June 2002

  • This grid-connected 1.8 kW system features Altair Energy’s Family-Safe system, which provides backup power for pre-selected appliances.
    Photo Courtsey Altair Energy
  • The PV panels on this California roof are connected to the grid and have a battery backup. Shown here is a Silicon-Film SunUPS System with 4.8 kW-rated peak-array capacity.
    Photo Courtsey AstroPower
  • Boston Edison commissioned this demonstration home, known as Impact 2000, to highlight future technology trends. The house features a 4.5 kW utility interactive PV system and solar thermal system, which form a uniform glass plane on the south roof.
    Photo Courtsey Solar Design Associates
  • The roof of this Massachusetts house is composed of 480 Sunslates that generate almost 7,700 kilowatt hours annually. Electrical installation: Solar Works, Wilton, New Hampshire; roof and flashing: Copper and Slate, Waltham, Massachusetts.
    Photo Courtsey Atlantis Energy Systems
  • 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

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.

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