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CAISO approves three tariff revisions for storage, DERs [free access]

October 7, 2020

The California Independent System Operator (CAISO) Board of Governors recently approved three tariff revisions related to energy storage and distributed energy resources (DER), directing staff to file the changes with the Federal Energy Regulatory Commission (FERC).


The three enhancements approved by the Board from the ISO’s Energy Storage and DERs Phase 4 proposal were—an optional end-of-hour, state-of-charge (level of charge of an electric battery relative to its capacity) biddable parameter for storage resources, establishing parameters to better reflect demand response resource operational characteristics, and streamlining market participation agreements for non-generator resource participants. The changes include a minimum and maximum MWh range.


Currently, state-of-charge is managed through self-scheduling, thus freezing out flexibility for the ISO and storage operators and not allowing a minimum or maximum state-of-charge range.


Additionally, some demand response programme (DRP) designs have a limited number of activations and set number of hours available for dispatch within a day. The Board approval now allows a demand response resource to identify the maximum number of hours per day the resource could be curtailed, with a 1 MW minimum curtailment size threshold.


Lastly, non-generator resources currently must execute both a participating load agreement and a participating generator agreement; the process for which has now been simplified by allowing non-generator resources to participate under a single participation agreement.


The revisions come at a time when FERC has recently issued the draft Order 2222—requiring the nation's regional transmission operators (RTOs) and independent system operators (ISOs) to develop rules that allow DER aggregators to bundle small-scale resources together and register those aggregations for wholesale market participation.