CAISO (California Independent System Operator) manages the flow of electricity across the high-voltage, long-distance power lines that make up 80 percent of California’s and a small part of Nevada’s grid. CAISO oversees energy trade on the day-ahead market (DAM) and the real-time market (RTM).

CAISO real-time market (RTM) is divided into 3 regions. Energy providers place bids for the quantity of electricity that they would like to provide to one of these regions at a given time and the minimum prices that they will accept. Supply and the demand not met through the day-ahead market determine prices. This report examines the CAISO RTM prices for 2016 and 2017 for the Northern region (NP-15)

Daily Pattern in the Average Hourly Real-Time Prices

The plot below shows the real-time prices averaged over each hour and year. The data are the 2016-2017 5-minute RTM prices for northern California (NP-15 CAISO zone).

The prices follow the ‘Duck Curve’: they are highest in late afternoon and evening, peak around 6 pm, and experience a smaller peak around 6 am. The pattern is more pronounced in the 2017’s data. The average hourly prices mask the volatility occurring within each hour.

Daily Pattern in Real-Time Prices (not Averaged by the Hour)

The plot below shows the real-time market prices that are posted every 5 minutes averaged over 2016 and 2017.

The 5-minute prices follow the general shape of the ‘duck curve’, but are difficult to predict at any given time.

Prices on the Real-Time Market for Dec 21 -Dec 24 2017.

The plot below displays the actual prices on the RTM for 4 days in December.

The prices fluctuate between -39 $/MWh and $660/MWh. On December 22 the prices changed from $50/MWh to $-39/MWh in 25 minutes.