The spectral response of a typical, cheap, silicon solar cell with just one layer is expected to look something like the graphs below. The way the junction responds is by producing current (A), and the way its being forced is with light power (W), so the vertical axis "response" is given in units of A/W (amperes/watt). If you're wondering where the ideal shaped graph came from, I think that's just based on the assumption of perfect quantum efficiency, one photon/second producing one electron/second. Plus there is a sharp cut-off at the wavelength where the photon energy equals the bandgap energy. BTW, if you drew the graph as a function of frequency, or photon energy, the line would slope the other way. Also the low response at low wavelength (high frequency) reflects the fact the incomming photons have much more energy than that needed move just one electron across the junction, but it's still just 1electron per photon, so energy is being lost/wasted at high photon energies.

Anyway the graphs below are for typical silicon solar cells with just one layer. Graphs for a different material, or a cell with multiple layers, those graphs will look, you know, different.

Solar cells will pretty much work with most visible and near-visible light you shine at it but it works far more effectively with whatever wavelengths the particular solar cell you're looking at is most sensitive to. To find what its sensitive to take a look at the cell's manufacturers datasheet for a graph with voltage output vs wavelength, wherever the peak(s) are, that's the "best light" for it.

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active| newest | oldestAnyway the graphs below are for typical silicon solar cells with just one layer. Graphs for a different material, or a cell with multiple layers, those graphs will look, you know, different.

The graphs below, I found here and here:

http://en.wikipedia.org/wiki/Photodiode

http://pvcdrom.pveducation.org/CELLOPER/spectral.htm