All eyes were CAISO last night as coastal heat brought high demand to SP15 all while surrounding regions were competing for megawatts on the ties. We’ve been covering the heat and the conditions in CAISO, including the natural gas market, in recent CAISO market flashes. We also wrote a recent battery report, titled ‘Heat is on Batteries’, about the impact of flexible generation including hydro and batteries in responding quickly in high demand scenarios. Now the tightest day has come and gone and it’s time to look back at the part batteries played in this September heat.

Figure 1 | CAISO Load Forecasts and Actuals, SP15 and NP15 Real-Time and Day-Ahead Prices

Peak demand for CAISO was impressive, falling short of the forecast, but still reaching 47.8 GW. PGE was able to stay below their forecasted peak load at 18.3 GW while SCE came in over at 25.3 GW. All in all, however, real-time prices were unimpressive. While day-ahead SP15 prices surpassed $600/MWH in the evening, real-time SP15 prices peaked just under $90/MWh while NP15 only managed $64/MWh. The figure above displays daily CAISO peak load, both forecasted and actual, as well as hourly day-ahead and real-time prices for both SP15 and NP15.