In its annual report on resource adequacy (RA) transactions, the CPUC reports the wrong result for the market price to be used for valuing capacity from the RA market data. The Commission’s decision issued in the PCIA rulemaking on establishing the CCA’s “exit fee” uses this value in error. In the CAISO energy and ancillary services markets, the market clearing price used to set the value of the energy portfolio is determined by the highest accepted bid in a single hour, and then averaged across all hours. In contrast, the average reported RA price in The 2017 Resource Adequacy Report incorrectly reports the average of all transactions. This would be equivalent to the CAISO reporting the average of all accepted bids, including those at zero or even negative, as the market clearing price.
The appropriate RA price metric is the highest RA transaction price for each month. This price represents the market equilibrium point at which a consumer is willing to pay the highest price given how low a price a supplier is willing to provide that quantity of the resource. (The other transactions are called “inframarginal” and such transactions are common in many markets.) In a full auction market, all transactions would clear at this single price, which is why the CAISO reports a single market clearing price for all transactions in a single hour. That should also be the case for the RA market price, except the time unit is a month.
Due to a lack of an auction for the moment, it is possible to manipulate the highest apparent price through a bilateral transaction. Instead, the Commission could choose a price near the highest point, but with sufficient market depth to mitigate potential manipulation. Using the 90th percentile transaction is one metric commonly used based on a quick survey of market price reports.