Nowcasting and forecasting of solar irradiance for solar energy electricity grid integration

Abstract

Solar energy systems are reaching a size of up to 50 MW electrical power. Their integration into the electricity grid as well as the management of regional grids with larger renewable shares requires extended irradiance forecasting. The paper uses an island power system as example for a regional grid with a large renewable energy share. The system was investigated under power generation deviation due to solar irradiance variations measured from ground and Earth observation. To optimize operations satellite nowcasting and short-term forecasting could be used. A 15 min advance notice about cloud cover, would be adequate to start up the back up systems and to reduce electrical reserve need in clear sky cases. For a test case, satellite nowcasting of clouds and irradiance, atmospheric modelling of aerosol load, numerical weather prediction of clouds and irradiance with deterministic and ensemble modeling is conceptually evaluated against electricity grid integration needs.