Online Data and Tools for Estimation of Solar Electricity in Africa - the PVGIS Approach

Photovoltaics (PV) holds great promise for developing countries where the solar resource is abundant and electricity grid penetration is low. Compared to other electricity generation systems, and to developing extended electricity grid within countries, small-scale off-grid applications are already now cost-effective. However, the economic constraints call for careful configuration of components of a PV system whose effective performance depends on the knowledge of the solar resource, which, although generally high, shows considerable geographical and seasonal variation. In this paper we present a solar radiation database and three interactive web applications for map-based query and for the performance assessment of photovoltaic installations. Besides Africa, the database covers also regions of the Mediterranean Basin and of South-West Asia. The solar radiation data were primarily computed from Meteosat satellite images and stored in the HelioClim-1 database and consist of daily and monthly totals of radiation on a horizontal surface, with a grid spatial resolution of 15’ x 15’. Without the existence of the Meteosat satellite, such a database would not have been possible, as the few stations of radiometric ground network in the region cannot provide a detailed structure of the solar resource. The HelioClim primary data represent the period 1985-2004. They were further processed to derive monthly and yearly averages of global irradiation on horizontal and inclined surfaces and to enhance the spatial resolution of the grid to 2 km x 2 km. Together with other geographic data the solar radiation was integrated into a geographical information system (GIS) for further processing. A set of PHP applications and embedded C programs was developed to provide open access to the data and to enable interactive assessment of the solar electricity potential at any location of the above mentioned region. The web interface is designed to display solar irradiation and PV performance data in the form of maps, graphs and tables. A location can be chosen either by browsing, zooming and clicking on a map, by selecting a country and city from a list, or by directly setting latitude and longitude values. The monthly and yearly values are displayed in a separate window. In the first web application, a user may browse selected map and query global irradiation incident on a PV module for different inclination angles. The second application simulates daily profiles of irradiance for a chosen month and module inclination and orientation. The application shows both clear-sky and average real-sky irradiance values for fix-mounted and tracking modules, taking into account also shadowing due to terrain features. The third tool estimates electricity generation for a chosen PV configuration. It also calculates optimum inclination and orientation of PV modules for a given location to maximize monthly or yearly energy yields. The database and the applications are accessible at http://re.jrc.cec.eu.int/pvgis/pv/imaps/imaps.htm.JRC.H.8-Renewable energie