I think the most fundamental answer is that the efficiency reduces when the temperature of the solar cell increases. The solar cell acts as a heat engine between the sun and the solar cell. There will be no energy conversion if the temperature of the solar cell reaches that of the sun. There is also a `temperature coefficient' for the open circuit voltage. It can be analytically calculated, and depends on the bandgap of the solar cell. The smaller the bandgap of the solar cell, the more rapidly its performance degrades with increasing temperature.
For all solar PV technologies, there is operating temperature range mainly suggested by the manufacturers which is based on STC conditions. However if not given by the manufacturers, there are equations that can be use to calculate it based on the parameters given by the manufacturers.
In general, the answer to your question is, for all PV systems the higher the increase in operational temperature the lower the efficiency of the module.
Hello Smita, the performance of the solar cell decreases with increasing temperature, because this increases the internal carrier recombination rates, caused by increased carrier concentrations. You can check the reference below for more information:
The temperature coefficient Gamma is 1/Pmax * dPmax/dT. It depends on cell technology and may be as small as -0.25%/K for some thin films, about -0.35%/K for advanced c-Si and -0.45%/K for standard c-Si. The value will be given on all datasheets as standard and is used in simulation programs like PVSYST.
For temperature effects relevant for solar cells with a photocurrent based on diffusing minority carriers, have a look at http://www.pveducation.org/pvcdrom/effect-of-temperature
In fact diffusion constant (both for electron and hole) and intrinsic carrier concentration will be increased when the temperature will increase and reverse saturation current density is increased when these two parameter increased.
With the increase of temperature, the reverse saturation current density is also increased which reduces open circuit voltage that leads to reduce the efficiency.