The battery fleet continues to be a focal point in both CAISO and ERCOT as both regions are seeing an influx of solar generation hit the midday period while the evening ramp still has plenty of power demand to deal with.  Over the years, the discussion around the belly of the duck has turned into an analogy of a giraffe’s neck as the sun sets, wind generation swings and load growth are front and center.  In CAISO, every day plays out where the battery charge profile reaches new heights in the middle of the day as the solar presence is instrumental in driving the hourly real-time settle prices into negative territory.

Figure 1| CAISO Battery Summary Profiles

Once the dust settles across the Golden State, the price action quickly reverts to positive territory with some hours spiking.  The volatility in both the midday charge and the evening ramp discharge periods makes sense when you analyze the battery operations.  For starters, without the demand in the midday block, the system operators would resort to more curtailments, which typically drives the price lower.....