Advances in Radiation Forecast Based on Regional Weather Models MM5 and WRF
With growing installations of solar power plants and integration into the electricity grid there is a demand for forecasting the energy production on a short-term basis for the entire electricity Management. Within IEA SHC Task 36, which ran from mid 2005 until mid 2011, METEOTEST made tests in the Alpine region with its operational numerical weather forecast models to forecast hourly global radiation of the next 72 hours or three days. With the regional weather models MM5 and WRF, setups with different horizontal resolutions were tested. Forecast data series were validated at Swiss measurement sites from the national meteorological network for each forecasted day separately. The first tests analyzed only the direct model output while at project end statistical post-processing methods were applied. In order to have comparable datasets only periods of more than 6 months are shown. As a measure for the quality of the forecast the root mean square error (RMSE) was chosen. Improvements in setups and post-processing techniques resulted in lowering the relative RMSE from 55% to 41% on hourly global radiation. With relatively low effort significant enhancements are possible.