Regional PV power prediction for improved grid integration

The contribution of power production from PV systems to the electricity supply is constantly increasing. An efficient use of the fluctuating solar power production will highly benefit from forecast information on the expected power production, as a basis for management of the electricity grids and trading on the energy market. We present and evaluate the regional PV power prediction system of University of Oldenburg and Meteocontrol GmbH providing forecasts of up to 2 days ahead with hourly resolution. The proposed approach is based on forecasts of the global model of the European Centre for Medium-Range Forecasts (ECMWF). It includes a post-processing procedure to derive optimised, site-specific irradiance forecasts and explicit physical modelling steps to convert the predicted irradiances to PV power. Finally, regional power forecasts are derived by up-scaling from a representative set of PV systems. The investigation of proper up-scaling is a special focus of this paper. We introduce a modified up-scaling approach, modelling the spatial distribution of the nominal power with a resolution of 1 degrees x 1 degrees. The operational PV power prediction system is evaluated in comparison to the modified up-scaling approach for the control areas of the two German transmission system operators 'transpower' and '50 Hertz' for the period 2.7.2009-30.4.2010. rmse values of the operational forecasts are in the range of 4-5% with respect to the nominal power for intra-day and day-ahead forecast horizons. Further improvement is achieved with the modified up-scaling approach. Copyright (C) 2010 John Wiley & Sons, Ltd.