You may already have a site and want to purchase a multiyear or TMY data time series for modelling purposes. GeoSUN Africa provides P50 and P90 TMY files based on satellite derived data time series from the SolarGIS data base in various formats (e.g. PVSyst, SAM, PVSol). The Solargis data base has been ground-truthed at a number of solar measurement stations throughout South Africa. Data from this model is considered bankable for small (<5 MW) projects. For larger PV plants, a combination of measured data from a nearby source (data up to 25 km away could be considered) and multiyear satellite-derived data is recommended.
The measured data is used to site-adapt (update) the satellite derived data set and reduce its uncertainty. If no solar data in the region can be sourced, we recommend installing an on-site solar measurement station. It is recommended to have 12 months of on-site data collection, after which the data is ready to be used for site-adaptation of the satellite derived data, reducing its uncertainty. Under the South African RE-IPPP programme, CSP developers are mandated to conduct on-site measurements for at least 12 months. GeoSUN Africa strongly recommends on-site measurements for PV or CPV plants above 5 MW as well.