Silicon's band gap is about 1.1 eV, corresponding (by chance) to about 1.1 um wavelength. Therefore a silicon solar cell will have practically no response to longer wavelengths than 1.1 um, and it would be senseless to measure its response in that band. The solar radiation reaching the earth drops dramatically below about 300 nm:
The optical properties of silicon measure at 300K 1. While a wide range of wavelengths is given here, silicon solar cells typical only operate from 400 to 1100 nm. There is a more up to date set of data in Green 2008 2. It is available in tabulated form from pvlighthouse as text and in graphical format.
A spectral response curve is shown below. The spectral response of a silicon solar cell under glass. At short wavelengths below 400 nm the glass absorbs most of the light and the cell response is very low. At intermediate wavelengths the cell approaches the ideal. At long wavelengths the response falls back to zero.
While a wide range of wavelengths is given here, silicon solar cells typical only operate from 400 to 1100 nm. There is a more up to date set of data in Green 2008 2. It is available in tabulated form from pvlighthouse as text and in graphical format. The data on this page is also available as an Excel spreadsheet.
Crystalline silicon solar cells are the most widely used solar cells, which have intrinsic limitation on the theoretical conversion efficiency (33.7% based on Shockley and Queisser's analysis) , and the actual conversion efficiency of crystalline silicon solar cells is as low as 20%.
With a band-gap of 1.12 eV, crystalline silicon cannot absorb light of wavelength less than 1100 nm. This causes a transmission loss of around 20%. These cells offer the highest quantum efficiency in the wavelength range from 800 nm to 1100 nm.