The Pacific Gas and Electric Company (PG&E) Excess Supply Demand Response program (XSP) demonstrates capabilities of demand-side resources to consume or decrease load as a service to the grid to address intermittency due to oversupply of renewables generation as distributed generation accelerates. The California PUC Load Shift Working Group noted in 2018 that the XSP was the only existing load shifting participation model. Designed to capture the full value of flexible resources to the grid it has been incorporated into initiatives across various consumer types including the California Energy Commission EPIC Total Charge Management project, PG&E’s Electric Vehicle Charge Network Load Management Plan, and the Pittsburg USD School Bus Renewables Integration Project.

In 2018, events were triggered using PG&E developed excess-supply forecasts. Of the total number of dispatches in 2018, 221 of the dispatched hours aligned with the CAISO’s reported renewable curtailment hours for 385 MW of consumption. On average, participants in the XSP can expect eight dispatches per month. Regulatory efforts have already begun in California to develop new models of participation for resources that can respond to load increase dispatches and lessons from the operation of the XSP have already gone on to inform these efforts. The XSP is the first step of what is to come with regards to developing participation models that can fully utilize resources with these flexible characteristics as a service to the grid.