Solargis approach on site-adaptation of satellite-based DNI and GHI time series
Accurate solar resource data is needed for planning, engineering and financing of a solar energy project. Site adaptation is an approach of reducing uncertainty in the estimate of solar resource by combining satellite-based long-term time series with short-term high-accuracy ground data measured near the project site.
We presented a review of methods and the SolarGIS approach at the SolarPACES 2015 conference held in Cape Town, in September 2015. Our experience shows that the best-achievable uncertainty of long-term assessment of annual values based on combining satellite and ground-measured data approximates to ±2% for GHI, and ±3.5% for DNI. This can be compared to the best-achievable uncertainty of the annual estimates of the SolarGIS satellite-based solar radiation model, which approximates to ±3.5% for GHI, and ±8% for DNI. The uncertainty is considered for 80% probability of occurrence, which translates to 90% probability of exceedance that is commonly used for calculation of P90 values.