Solar panels that float on water? Very impressive and very cool:

Already, 144 solar panels sit atop pontoons moored on a three-acre irrigation pond surrounded by vineyards in Petaluma in Sonoma County. Some 35 miles to the north, in the heart of the Napa Valley, another array of 994 solar panels covers the surface of a pond at the Far Niente Winery.

"Vineyard land in this part of the Napa Valley runs somewhere between $200,000 and $300,000 an acre," said Larry Maguire, Far Niente's chief executive. "We wanted to go solar but we didn't want to pull out vines."

. . . . The solar panel aqua farms have drawn interest from municipal water agencies, farmers and mining companies enticed by the prospect of finding a new use for — and new revenue from — their liquid assets, solar executives said.

. . .

Solar entrepreneurs had hoped to persuade the California State Water Project to cover the 400-mile California Aqueduct with photovoltaic panels. The panels could then generate electricity in the canal that irrigates the agricultural empire of the Central Valley and helps supply water to 25 million Californians.

. . .

That is Sunengy's strategy. Mr. Connor said the company was looking to developing countries to turn hydroelectric dams and village reservoirs into giant batteries.

"Any solar power you generate on the dam allows you to feed the transmission line and save water in the dam for use on rainy days or at night," he said.

Sunengy's plan would deploy rafts of solar units that use a plastic lens to track the sun and concentrate sunlight on small photovoltaic cells that use less expensive silicon than conventional cells. In high winds, the lens stows under the water.

"If you have a drought on a hydroelectric dam, your asset is dead," Mr. Connor said. "If you have solar power on that dam, you can continue to generate electricity."

An interesting benefit to floating solar power plants would also be to control algae.

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