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Avoiding Sun Burn: Rooftop Solar Panel Safety Tests
New facilities use everything from guns to temperature extremes to test the safety of photovoltaics and other clean energy technologies
A new2,100-square-meter building outside Frankfurt, Germany, houses a series of chambers that can simulate a hot, humid day or temperatures so frigid that metals crack, and every punishing weatherscenarioin between. It's all for testing one product—solar photovoltaic panels—and it's the third such facility opened since 2008.

Underwriters Laboratories, perhaps most recognizable for the ubiquitous"UL" in a circle that is printed on many gadgets, was founded back in the late 19th century by insurance companies looking to forestall the fires endemic to the new era of electrification by safetycertifying electrical products. And that's exactly what UL is doing today for solar panels, which have grown from roughly 20,000 modules made or installed in the U.S. alone in 2000 to more than 520,000modules by 2008, according to theU.S. Department of Energy.

"In the U.S. we tend to build our houses out of fuel [wood]. Then we put these solar panels on the roof," says UL CEO Keith Williams."Most of our activity right now is related to safety testing for solar panels and modules as well as electrical components that would connect the solar panel to the house and grid."

That doesn'tmean such panels aren't safe, just that they pose at least a fire threat if improperly connected. UL also tests the products' capacity to stand up to the rigors of home use. That means shooting sphericalice cubes from a pneumatic gun to mimic a hailstorm, baking panels at temperatures of up to 90 degrees Celsius, and blasting them with concentrated spotlights to put heat and thermal stress onspecific parts of a given panel. The units are even subjected to high humidity followed by a chill-down to –40 degrees C—a condition unlikely to occur in the real world—to see if the PV will crack or...