Temporal and spatial solar resource variation by analysis of measured irradiance in Geba catchment, North Ethiopia

Abstract

The availability of solar energy resource information in Ethiopia is limited due to the lack of ground measurement stations. The aim of this work was, therefore, to estimate the temporal variation and spatial distribution of solar radiation for Geba catchment located in the Northern part of Ethiopia based on four selected measurement sites. To achieve this, ground measurement data at ten-minute interval that has been recorded for five years was employed. Time series data and temporal variation analysis were done for all the sites. The spatial distribution analysis was carried out by interpolation of the data from the sites across the catchment using Inverse Distance Weight (IDW) method of the ArcGIS software.The temporal data analysis indicated higher solar radiation of greater than 5 kWh/m2/day during the dry months of September to May and in the range of 3–4 kWh/m2/day during the rainy season of June to August. The result of the analysis on spatial distribution of solar radiation showed 5%–7.5% variation with daily average solar radiation of 5.6 kWh/m2/day across the catchment. Areas in central part around Mekelle and southern part around Mayderhu site have relatively higher solar radiation.