CAISO

CAISO's defining physics is the daily solar cycle. Utility-scale solar floods the middle of the day, hollowing out net load, and then exits within a couple of hours of sunset, right as demand peaks. That evening ramp sets the tempo for everything else: when batteries charge and discharge, when gas is called, when imports matter, and when prices spike. It is also why CAISO publishes an unusually clean storage series: five-minute net battery output for the whole footprint, positive discharging, negative charging.

The market itself is nodal and component-split. CAISO prices carry explicit energy, congestion, and loss components at every pricing node, in both the day-ahead market and 15-minute real-time pre-dispatch, so a price separation can actually be decomposed rather than guessed at. Constraint evidence is public too: five-minute shadow prices on interties show when import and export paths to neighboring balancing areas bind and in which direction, and nomogram shadow prices flag the multi-element stability limits that single-line views miss.

Beyond its own borders, CAISO runs two separate Western market services, not one expanded territory. The Western Energy Imbalance Market (WEIM) is real-time-only, reaching roughly two dozen independent balancing authorities across the West without folding them into CAISO's own footprint. The Extended Day-Ahead Market (EDAM), live since May 1, 2026, adds day-ahead co-optimization for a much smaller set — so far just CAISO and PacifiCorp's East and West balancing areas. That makes the tie constraints and border prices in this data the visible seam between California and everyone it trades with.