Benchmark Forecasts – DRAFT

The Arbiter will include the capability to create and evaluate benchmark irradiance, power, and net load forecasts. Comparisons of test forecasts against benchmark forecasts can help forecast users and developers understand the relative merits of models. The most appropriate benchmark will depend on the use case and forecast horizon. We believe that the following benchmark forecast attributes are appropriate for most use cases:

Additional information on the Arbiter’s benchmark forecast capabilities will be available in January, 2019.

If you’re attending AMS 2019, please visit our Benchmark Solar Power Forecasts poster on Monday, January 7 from 4:00 - 6:00 PM.

Built-in benchmark forecasts

The Arbiter will provide built-in support for the following benchmark options.

Intrahour horizons

Intraday and longer horizons

The Arbiter will derive irradiance forecasts from NAM and GFS cloud cover forecasts to properly account for the solar position and time averaging. The Arbiter will include options for bias-corrected NWP-based benchmark forecasts.


Calibration of probabilistic benchmark forecasts is a topic of discussion.

User-supplied benchmark forecasts

Some evalulation applications may require users to provide their own benchmark forecasts. For example, Solar Forecasting 2, Topic Area 2 teams may choose to run an earlier version of WRF Solar and then upload its forecasts for particular evaluation points. Benchmark models should be run in consultation with the framework administrators. The framework will accept uploaded forecasts for predefined evaluation point or area-average values. The framework will not accept gridded datasets.

PV power forecasts

The Arbiter will include functionality for converting benchmark solar irradiance forecasts into benchmark solar power forecasts in a simple, auditable manner. The Arbiter will use solar power modeling functions from the pvlib-python library.

Net load forecasts

Net load is defined here as true system load minus behind the meter PV. Net load is the load that must be served with utility scale resources, regardless of whether or not they are dispatchable, conventional, or renewable. We make no allowance for wind power or utility scale solar power. Therefore, net load is not equal to the load that must be served with conventional generation.

The Arbiter will include the capability to create benchmark net load forecasts as defined above. This requires the development of a simple benchmark load model.