A sinusoidal model to assess PV generation from daily irradiation data

The estimation of photovoltaic (PV) efficiency depends on the solar cell temperature, which varies with ambient temperature and solar irradiation. When only daily averages are available, for instance, when assessing solar potential in a future climate, the standard procedure leads to a non-negligible error in the estimation of PV generation, as it disregards the fact that changes in efficiency at low irradiance are less relevant than changes in efficiency at high irradiance. A correction factor based on a sinusoidal model for solar irradiation and temperature is proposed and tested for locations with diverse latitudes and climates. The results show that this approach features random and bias errors below 2%, at least three times smaller than the standard averaging method, thus validating its application for estimation of PV generation.