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Solar Tubes More Efficient

It would seem counter intuitive that cylinder shaped solar panels would be more efficient and cost effective than flat. After all, anything with a curve is usually more expensive to make, and the loss of perpendicular surface area to the sun should make these solar tubes less efficient…right?

Well according to Solyndra, the company who makes these cylindrical solar cells, many factors are not taken into consideration. “With a cylinder, we are collecting light from all angles, even collecting diffuse light,” says CEO Chris Gronet, who founded the solar cylinder company in 2005 based on an idea he had late one night while pondering less expensive ways to install photovoltaic panels. Because the arrays do not have to be angled or anchored into the roof, he adds, “we have half the installation cost and can install in one third the time.”

These cells essentially look like dark flourescent light bulbs and have many advantages over their flat counterparts.

Solyndra is now churning out copper-indium-gallium-selenide (CIGS) thin-film solar cells, wrapped into a cylindrical shape and encased in glass. This design not only seals out moisture but allows the glass to act as a sunlight concentrator, funneling photons onto the thin film, according to Gronet. He says the Fremont plant, which opened in the spring, will ultimately be capable of producing 110 megawatts worth of solar cylinders annually, but he declined to specify how many cylinders that is.

The company says that the solar cylinders—paired with a roof painted white to better reflect sunlight—can collect 20 percent more sunshine than their conventional flat counterparts. The estimate is based on 50 kilowatts worth of the tubular cells that the company installed on its own roof.

As it stands, Solyndra’s CIGS solar cells convert as much as 14 percent of the sunlight that hits them to electricity and, all told, Gronet expects that a Solyndra system will deliver twice as many kilowatt-hours of electricity from a given rooftop.

The cylindrical design also allows Solyndra to lay its arrays flat and to space them so that the wind can flow through them, rather than lift them up like it can with angled arrays. This means that the solar cylinders can be installed without affixing them onto the roof—and still withstand up to 130 mile-per-hour (209 kilometer-per-hour) winds.

via sciam

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