A relative normalized irradiance-dependent efficiency of photovoltaic modules is recommended as an objective means of quantifying their behaviour under variable irradiance conditions. It allows users to decouple the irradiance-dependent behaviour of photovoltaic modules from their temperature dependence. This criterion is shown to have a broad applicability in diagnostics by manufacturers and users of photovoltaic moduleâ€™s data sheets. A recommendation is made for the following study to require that the measured power-irradiance, power-temperature matrix according to the new standard could be incorporated. With the increase in temperature the rate of photon generation increases thus reverse saturation current increases rapidly and these results on reduction in band gap. Hence this leads to marginal changes in current but major changes in voltage.