Solar Energy, Made In The Shade

What if you want to install a solar energy panel on the roof of your home, but that roof isn't bathed in sunshine all day long?

That's the problem a team of researchers from the Massachusetts Institute of Technology (MIT), who recently won the school's annual clean energy competition, say they have solved.

Residential rooftop solar panels can lose up to 30 percent of their potential energy a year if shade from trees or clouds even occasionally blocks direct sunlight. According to research team member Bessma Alarbou, "A small percentage of shading can cause significant losses."

The problem with conventional solar panels is that if one cell is not performing to its full potential, it drags down the performance of the other cells in the solar array. Current technology adds devices that isolate underperforming cells to prevent this.

But Aljarbou says that effectively subtracts all the potential of the underperforming cells from the panel. The upside is that it keeps them from affecting neighboring cells. The downside is that it reduces the panel's overall potential for absorbing solar energy.

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The MIT team integrated what's called a "power-balance circuit" into a solar panel to prevent that loss of potential.

The new circuit balances power between cells that are receiving direct sunlight with those that aren't, thereby harvesting double the amount of solar energy than traditional solutions can, at a very low cost.

So far, the new circuit has only been tested in the lab, but the team of young researchers has formed a company, United Solar, that will create a prototype that can be manufactured and marketed.

On April 28, their project - with the catchphrase "shade happens" - won both of MIT's CEP grand prizes: the DOE Energy Efficiency and Renewable Energy Clean Energy Prize, worth $100,000, and the NSTAR MIT Clean Energy Prize, worth $125,000.

By Andy Tully of Oilprice.com