Estimation of sunshine duration from the global irradiance measured by a photovoltaic silicon solar cell

Sunshine duration can be estimated using photovoltaic solar cells instead of conventional pyranometers or pyrheliometers, which are more expensive and therefore not suitable for low cost measurement applications in developing regions. A one-year meteorological dataset from Nicosia (Cyprus) including direct irradiance, global irradiance from a pyranometer and global irradiance from a reference PV cell was used to calculate sunshine duration following the WMO pyrheliometric method and three pyranometric methods by WMO Slob and Monna, Hinssen–Knap and Olivieri. Pyranometric algorithms were adapted to the tilted pyranometer and reference solar cell. Main results indicate that all the pyranometric algorithms underestimated sunshine duration over the span of a year in Cyprus in comparison with the reference pyrheliometric method; and that results between the pyranometer and the solar cell were comparable. The PV silicon solar cell is capable of measuring sunshine duration on a daily basis with an uncertainty similar to the obtained with a pyranometer when using the Olivieri algorithm.