Solar forecasting by meso-ensemble prediction system-case study of Hokkaido area in Japan and challenges in areas with winter snowfall

Photovoltaic (PV) power generation systems (hereafter referred to as "PV") are being installed in large numbers in Japan. From the viewpoint of electricity supply and demand, PV should generate electricity only during the daytime, and supply from other sources (e.g. thermal power in Japan) should be reduced during that time. Thermal power plants need to plan the next day’s operation by the evening of the previous day. Therefore, information on the PV power forecasts for the next day (day-ahead forecast is necessary). In actual operation, the results of the numerical weather prediction model (NWP) are used. The PV power forecast is greatly affected by the forecast of global horizontal irradiance (GHI). It is also important to use ensemble forecasting to improve the accuracy of forecasting and to understand the uncertainty of forecasting in advance. In this paper, we present the results of a case study analysis of GHI forecasts (for the Hokkaido Electric Power Company area) by weather conditions using the meso-ensemble prediction system (hereafter referred to as MEPS). In addition, the presence of snow on the PV also causes a discrepancy in PV power forecasts. The presence of snow cover on PV will also be discussed.