Assessment and validation of global horizontal radiation: a case study in Mauritius

Validated solar maps are very crucial for a holistic site selection, design and financial evaluation of photovoltaic (PV) projects. During this research, the temporal and spatial variations of global horizontal solar radiation are investigated. The performance of PV systems has been analyzed. A solar map has been developed and validated against performance of PV systems for Mauritius. For the purpose, initially global horizontal irradiance was measured at intervals of 30 s across five sites in the country since 2013. Measurement data showed that yearly averaged daily insolation varied between 3.25 kWh/m(2) and 5.04 kWh/m(2) across the country. Angstrom Prescott (AP) coefficients were then calibrated in order to model daily radiation at the measurement sites. AP coefficient, a, varied between 0.132 and 0.278 while, a + b varied between 0.662 and 0.831. With the aid of sunshine hour data obtained from Mauritius Meteorological Services, monthly averaged and yearly averaged insolation are computed for additional six sites in order to have a wide coverage of the country. Statistical performance indicators were computed and results showed good agreement between measurement and the linear univariate AP model. Yearly averaged daily global horizontal insolation for eleven sites were used to generate a solar map. The average annual insolation levels have been estimated to vary between 1237 kWh/m(2) and 1901 kWh/m(2) over the island. The latter values represent the average capacity utilization factor of photovoltaic plants, which are estimated to vary between 14.1% and 21.7%. The results add up to highly valuable information on solar exposure for adoption of off-grid and grid tied photovoltaic technologies.