Estimation of daily solar radiation flux at Western Highland, Simikot, Nepal using RadEst 3.0 software

A precise knowledge of solar radiation flux distribution in each particular geographical location is key to the promotion of solar energy technology. The amount of solar radiation flux can be estimated using experimental data and modeling parameters as well. This research work is based on the use of the RadEst 3.0 ver software to estimate daily solar radiation flux at high altitude mountain area using meteorological parameters such as precipitation, maximum and minimum temperature, and solar radiation of Simikot, Nepal (Lat. 29.967 °N, Lon. 81.833 °E and Alt. 2990.0 m). The radiation is estimated using four different models: Bristow and Campbell, Campbell and Donatelli, Donatelli and Bellocchi, Donatelli-Campbell-Bristow-Bellocchi as the product of the estimated transmissivity of radiation for each model and radiation outside the earth’s atmosphere and compared with measured solar radiation. The model parameters are fitted in two years (2012 and 2015) ground measured data by using iterative procedures. The performance of the models was evaluated using statistical tools such as root mean square error, mean bias error, mean percentage error, co-efficient of residual mass, and coefficient of determination. The graphics and statistical evaluation suggested that among the four models, the Donatelli-Campbell-Bristow-Bellocchi model is better than others for Simikot. The value of statistical tools for this last model are 3.012 MJ/m2/day, −0.029 MJ/m2/day, 2.402%, 0.002 MJ/m2/day and 0.595 respectively. The finding empirical coefficients of different models can be utilized to estimate of solar radiation flux at similar geographical locations in Nepal.