Intra-hour to day-ahead global and direct solar irradiance forecasts

Abstract:

In solar energy literature one can find the bits and pieces necessary to create solar irradiance forecasts that cover time scales ranging from intra-hour to days-ahead.
The caveat is that rarely these models cover more than a single time scale making them unattractive to solar power producers that require accurate forecasts for all time scales. Thus, in this work we present a framework that can be used to create direct and global irradiance forecasts for intra-hour, intra-day and days-ahead in real time.

The methodology presented uses ground telemetry, local sky images (if available), satellite images and the output of numerical weather predictions (NWP) models. Given that ground telemetry must be available and satellite images and NWP data are freely available for the entire US territory this methodology can be applied to any location of interest.

Furthermore, the proposed methodology uses different figures of metric depending on the forecast horizon. For instance, in the intra-hour time scale the goal is to predict large ramps in irradiance and not bulk error metrics such as the RMSE or MAE.

This methodology is applied to locations in California with varying climates in order to assess its performance.