New Empirical Models for Estimation of Global Solar Radiation around the Earth Surface

摘要

Solar radiation is a primary driver for many physical, chemical and biological processes on the earth's surface. Complete and accurate solar radiation data at a specific region are quite indispensable to the solar energy related research. For locations where measured values are not available, a number of formulas and models have been developed to estimate solar radiation. This study aimed to develop new model(s) for estimating global solar radiation data using meteorological parameters. Measured solar radiation, air temperature, relative humidity, wind and moisture data from 210 sites around the earth was used for model development for estimating the monthly average daily global radiation on a horizontal surface. Several models and correlations that embrace such variables as the fraction of air temperature, relative humidity, wind and moisture, latitude, longitude and altitude have been selected. In this study, using air temperature, relative humidity, wind and moisture and derived parameters as independent variables, the most accurate equations have been obtained. The results show that the general formula developed could be used for the estimation of solar radiation with the local site parameters. After validation with 665 data sites on these models, finally two candidate models have been proposed. These models are capable of covering 50% of the land area on earth surface between latitude ± 30°, enabling estimation accuracy to 93% of sites, with an estimation error (RMSE) limiting to 15%. Thus it is envisaged that, the proposed equations can be used to estimate the monthly average daily global solar in area where the radiation data is missing or not available. This helps in assessing the solar energy potential over large area.