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"Company creates solar power that floats in water"

Written by Jim Motavalli

SAN DIEGO — Sometimes you encounter an idea so seemingly brilliant  you wonder why you didn’t think of it yourself. OK, here goes:  utility-grade “concentrating” solar power in water. You’re not applauding — what’s going on?

I know it doesn’t sound all that incredible at first, but think about it. Solar is only important if it gets big. Right now, it’s still a pitiful  percentage of the energy mix. If we’re ever going to be able to  comfortably answer the questions about electric cars charging up from a  dirty grid, we have to start injecting more renewable energy into the  mix, and that’s what’s so great about concentrating solar, which through  the use of focusing mirrors and other tech substantially increases the  electron yield of a photovoltaic array.

Pyron Solar test installationMost  concentrating solar installations also swivel to track the sun during  the day, which is far more effective than a fixed array. In Pyron Solar’s small 20-kilowatt test installation in San Diego (at left), the solar panels sit in what looks like a big above-ground  swimming pool, and because they’re floating, the water acts as a bearing  and they can be moved very easily on a ring — with a tiny 12-volt  electric motor of less than one horsepower.

Installations like this aren’t intended for the open ocean, of  course, but, as Pyron President Stephanie Rosenthal explained to me, for  placid rivers, ponds and man-made pools. There’s no reason systems like  this can’t be installed in wastewater, or in reservoirs, or even in the  water hazards on golf courses. The water host also means they can be  mounted low to the ground, kept cool on hot days, and easily withstand  weather events that could topple a tall solar tower. The system avoids  the problem of panels shading each other, and it also has a very small  “footprint” — with three acres, you can install a megawatt of solar.

Pyron’s Joe Bentley, the chief technology officer, pushed down on  one of the connected panels with his finger, and it gave way but didn’t  lose its relationship with the sun. As he did that, I could see, down in  the pool, the mosquito-eating fish that Pyron had installed to help keep the water clean. (There were supposed to be tiny sharks, too, but I didn’t see them.)

Pyron uses an acrylic concentrating lens, which focuses the  equivalent of the light from 6,500 suns on a small optical device, which  then spreads it across the surface of the solar cell. The system was  originally developed by a German scientist in 1986, and Pyron’s test  version represents something of a dream fulfilled. It’s installed at San  Diego Gas & Electric’s Mission Controls/Skills Training Center  (formidable security!), which is an indication of the utility’s interest in the technology. (SDG&E is a major investor in concentrating solar.)

The installation I saw was test-sized — 50 of them would equal a  megawatt. Electricity from Pyron Solar’s arrays “should be below 10  cents per kilowatt-hour,” Rosenthal told me. “That’s a very attractive  proposition.” Pyron isn’t quite ready for commercialization, but the  team is working on its third-generation technology, which is the version  that will go on sale.

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Mr. Motavalli writes for The New York Times, CBS MoneyWatch, and NPR’s Car Talk, among others. He is an author, editor, and two-time winner of the Global Media Award from the Population Institute.