The most important metric for solar panels is the cost of generating a given amount of power. As this number drops, the case for using solar power becomes increasingly compelling.
The technical specification that attracts the most attention is energy conversion efficiency. This is a measure of what fraction of the incoming solar energy is converted into electrical energy. The world record using exotic and expensive technologies is about 45%. Most commercially available panels, on the other hand, have efficiencies no higher than 15% or so.
Off-hand, this sounds like a pretty low number. However, there are two mitigating factors: one is that there is an awful lot of solar energy out there to work with and the other is that it is free anyway, so efficiency is not all that important.
That being said, the efficiency of solar panels does determine how many of them are needed to produce a given amount of power and if the amount of space available is limited, this is important.
As a result, solar cell researchers are constantly working to increase solar cell efficiency. A new company in North Caroline called Semprius is developing a solar cell technology that stacks up multiple layers of different semiconductors that each collect different frequencies of light. They claim they will be able to reach efficiencies as high as 50% by this method.
It remains to be seen if this kind of solar panel can be made at low cost. If they can be, the future of this solar start-up company is very bright indeed.
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Photo, posted August 14, 2013, courtesy of The Bakken Museum via Flickr.
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Earth Wise is a production of WAMC Northeast Public Radio.