Dispelling a Common Myth about Solar Energy

When people hear the term “solar energy,” they instantly think of solar panels and photovoltaic (PV) technology, whereby sunlight is converted into electricity. This is a common misconception. In fact, solar energy experts wish the term "solar energy" was not pegged with PV, giving the impression that solar energy is expensive. It’s not.

Under the umbrella of solar energy is solar thermal technology and PV technology. Solar thermal technology is very different than solar panel, or PV, technology. Solar thermal concentrates sunlight to create heat, which is used to run a heat engine that turns a generator to make electricity. And unlike solar panels that are only effective during daylight hours, with solar thermal, heat can be stored during the day and then converted into electricity at night.

Their efficiency ratings and prices are also very different. PV only has a 12- to 19-percent efficiency rating. Bright sunshine produces 300 BTU/square foot. PV converts 12 to 19 percent of that energy into usable electricity at a cost of 25 to 35 cents per kilowatt hour. Solar thermal, which includes solar air and solar water, delivers much higher efficiencies. Solar water offers 55-percent efficiency at 12 to 15 cents per kilowatt hour, and solar air delivers 80 percent at 3 to 9 cents per kilowatt hour.

Solar thermal is a much more easy and efficient method, but doesn’t get as much attention as PV.

“There’s a tremendous amount of subsidies going into PV that it’s not a self-sustainable business,” said Christian Vachon, president of Enerconcept Technologies. “And if you want to make margins, you have to have them made in China. You see companies like Solyndra and Evergreen falling in that trap. Governments should stop thinking that solar is expensive and needs to be heavily subsidized in order to be sustainable. With PV, we’re putting all our eggs in the longest possible payback basket. Our leaders should instead focus on an energy policy that promotes the lowest-cost energy technology.”

It’s interesting that a technology that was used in the 1800s is making a comeback today. In the 1890s, homes and buildings employed black-painted, roof-mounted water tanks, and in 1896, Clarence Kemp of Baltimore patented the first solar thermal system. In 1897, nearly 30 percent of the houses in Pasadena, Calif., had solar water heaters.

Today, Japan and Israel lead the world in the adoption of solar thermal energy. In Japan, 10 million solar thermal systems are in use, and in Israel, 90 percent of homes use solar hot water heating. In the United States, solar thermal energy has some catching up to do—approximately 1.5 million homes have solar thermal systems—but this clean technology has the opportunity to lead us into a future that relies on renewable energy.

Posted by Sherleen H. Mahoney on Oct 10, 2011

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