Solar Resource Assessment for Sri Lanka and Maldives

The countries of Sri Lanka and the Maldives lie within the equatorial belt, a region where substantial solar energy resources exist throughout much of the year in adequate quantities for many applications, including solar water heating, solar electricity, and desalination. The extent of solar resources in Sri Lanka has been estimated in the past based on a study of the daily total direct sunshinehours recorded at a number of weather and agricultural stations throughout the country. These data have been applied to the well-known Angstrom relationship in order to obtain an estimate of the distribution of monthly average daily total solar resources at these stations. This study is an effort in improve on these estimates in two ways: (1) to apply a gridded cloud cover database at a 40-kmresolution to produce updated monthly average daily total estimates of all solar resources (global horizontal, DNI, and diffuse) for the country, and (2) to input hourly or three-hourly cloud cover observations made at nine weather stations in Sri Lanka and two in the Maldives into a solar model that produces estimates of hourly solar radiation values of the direct normal, global, and diffuseresource covering the length of the observational period. Details and results of these studies are summarized in this report.