2011 Ex Post Load Impact Evaluation of California's Statewide Base Interruptible Program

This report provides the 2011 ex post load impact estimates for the Base Interruptible Program (BIP), which is offered by each of California’s three major investor-owned utilities, Southern California Edison (SCE), Pacific Gas and Electric (PG&E) and San Diego Gas & Electric (SDG&E). Each utility called a territory-wide test BIP event in 2011. SCE called a test event on September 21 from 2 PM to 4 PM, which provided an average load drop per customer of 790 kW and an aggregate impact of 522 MW. This represents nearly a 70% reduction relative to the estimated reference load of 751 MW. PG&E implemented a test event on September 7 from 3 PM to 5 PM, which provided an average load drop per customer of 827.5 kW and an aggregate impact of 183.7 MW. This represents roughly an 83% reduction relative to the reference load of 220.9 MW. SDG&E called a BIP test event on August 18 that lasted from 12 PM to 4 PM for BIP option A customers and 3 PM to 6 PM for the single BIP option B customer. From 3 PM to 4 PM when all SDG&E BIP customers were participating in the event, the average load drop per customer was 114.1 kW and the aggregate impact was 2.4 MW. This represents roughly a 35% reduction relative to the reference load of 6.9 MW. In addition to the 2011 ex post load impact estimates, the report provides an overview of the program and detailed discussion of the evaluation methodology.

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