PV Gap

Kathleen Said:

what is the prospect of solar cells becoming really succesful?

We Answered:

Pretty good. The real question is how long will it take for either to change.

First off, the efficiency of solar cells has already grown by leaps and bounds, with the disadvantage being that the methods with the greatest efficiency are very expensive.

There's a couple of ways to improve the efficiency, perhaps without the associated increase in cost.

1) Increase the spectrum of light that can be converted to electricity. Currently, solar cells only convert a very small range of light frequencies to electricity. You could theoretically expand that range by combining different materials in a solar array, but if the crystal lattices of the different materials differ too much efficiency also suffers.

A new development, discovered during development of LEDs rather than solar cells, could expand the range of frequencies that could be converted to electricity without increasing the cost. Indium gallium nitride holds the promise of increasing efficiency to 50 to 70 percent (the best current solar cells run around 30%). The material is very defect tolerant, meaning the crystal lattices don't have to match so precisely, decreasing the cost of production, plus it has a high heat capacity. Of course, a p-type version compatible with indium gallium nitride still needs to be developed, but if one is found, the efficiency of solar cells would leap while the cost would plummet.

2) Increase the number of electrons emitted in response to being struck by photons of light. Current solar cells can convert one photon of solar energy to one electron with the rest being lost as heat. Nanotechnology could increase that to three electrons per photon of solar energy, increasing solar cell efficiency to around 65%.