Total, beam and diffuse solar radiation studies for Rohri, Sindh

ABSTRACT

Global Solar Radiation [H], extraterrestrial [H[o]], diffuse [H[d]] and beam radiation values [H[b]] for Rohri, Sindh [Latitude 27.67[degree]N and Longitude 68.9[degree]E] have been calculated on horizontal surfaces using sunshine hour data [n] of the areas, following a number of methods. The calculated global solar radiation is then compared with the global solar radiation presented by the NASA SSE [22-year] model. The mean bias error [MBE], root mean square error [RMSE], and mean percentage error [MPE] for global solar radiation are also considered. Diffuse radiation is calculated using methods proposed by Page and Liu and Jordan [L-J] and compared with the H[d] obtained from NASA. Diffuse Radiation from the Page method is found to be higher than in the L-J method. Moreover, the monthly clearness index [K[T]] is compared with the measured clearness index. The ratio K[T] signifies a clear sky almost all year round except for the months of June to August. This may be due to the monsoon season where the cloud cover is expected to be thicker compared to the rest of the year. From the estimated results, it appears that solar radiation can be utilized very efficiently throughout the year for photovoltaic and thermal applications.