Inter-comparability of solar radiation databases in Indian context

Abstract

Solar radiation resource assessment is one of the most important exercises towards implementation of large-scale solar power projects. The quality of resource makes significant impact on the selection of technology to be used at a specific location for solar electricity generation. In this study, inter-comparability of several solar radiation databases (i.e. ground, satellite and statistical) is assessed in Indian context. The long-term measured Global Horizontal Irradiance (GHI) over 23 representative locations is compared with the GHI obtained from satellite and weather databases. Direct Normal Irradiance (DNI) is estimated through long-term measured global horizontal and diffuse irradiance using basic sun–earth geometry and compared with the DNI obtained from different solar radiation and weather databases. It is observed that with respect to long-term measured data of GHI the average range of deviation varied from 0.20% to 22.53% whereas DNI varied from 0.64% to 35.12% across select locations. Impact of the variation due to solar radiation resource assessment on the annual electricity generation and levelized cost of electricity of grid-connected solar power projects is also underlined.