The infra-red region does not have enough energy to pluck the electrons and send them to the higher energy levels. Whereas the ultra-violet region has extra energy than required by the electrons of the solar cell to start conducting, resulting in the heating of the solar cell which further reduces the efficiency of the cell.
Amount of light
When it is dark, the solar cell stops conducting as there is no sunlight. As the amount of light increases gradually with the rise of the sun, the output of the solar cell also starts responding in the same manner. There comes a saturation point when the solar cell gives no additional current even after increasing the amount of the light.
The electromagnetic spectrum is the band of energies including Gamma rays, X-rays, Ultra-violet, Visible rays, Infra-red, micro waves, and the radio waves. The solar cell produces electricity in the visible region of the spectrum and this region is also detectable by the human eye.
The solar panels work best with the sunlight that is why we see panels outside the houses, at the top of the roofs inclined at a certain angle with the sun rays. The solar cell also produces electricity with the artificial light like produced by the florescent lamp (CFL) and the incandescent bulb. Because the energy of these artificial sources of light falls under the visible spectrum as required by the solar cell to produce the current. But the amount of light produce by these artificial sources is very less, therefore we cannot run big solar panels under this light. Although we can power and run small devices like solar calculators, watches and mini toys like a small solar car.