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From Through Apply dates

Daily DART spread

Average of the 24 hourly spreads each trading day at the selected hub. Blue days: day-ahead cleared above real-time (INCs paid). Red days: real-time ran above day-ahead (DECs paid).

DART fingerprint — hour × day

Each cell is one hour's spread. Vertical red bands are real-time price excursions; persistent horizontal structure is the systematic hourly bias virtual bids chase.

Inspect one hour

Click a heatmap cell or daily bar, or choose a date and hour. The daily bar opens that day's largest absolute spread.

Trading date Hour ending Inspect hour

Select an hour to connect its prices and forecast revisions.

Forecast skill — how much the ISO's view moves between DA and RT

Trailing 7-day mean absolute error and bias. Load: the day-ahead demand forecast vs. the RTPD (real-time market) forecast for the same hours — the same-definition demand surprise the RT market trades on (the published "actual integrated load" sits on a different BTM-solar accounting basis, so it is not compared directly). Wind & solar: DA production forecast vs. actual generation; midday economic curtailment shows up as persistent positive bias in summer.

Spread conditional on net-load surprise

Hourly observations bucketed by how far real time's view of net load moved from day-ahead's: (RTPD load fcst − DAM load fcst) − (wind + solar actual − DA forecast). When net load comes in above the DA view (right side), real time must buy more energy than the DA market cleared — the spread should go negative. Bars are the mean spread per bucket; the label is the share of hours with DART > 0.

Virtual-bidding intel

Left: expected value of a 1 MW INC by hour-ending over the selected range (a negative bar means the DEC side paid). Right: cumulative P&L of mechanical 1 MW strategies — INC across the evening ramp, DEC across midday, and a trailing-14-day signal that takes the historically profitable side of each hour. Gross of fees, bid-cost recovery, and uplift; this is a diagnostic, not advice.

Data table

The long view — system-wide DART since 2020

System DLAP benchmark · independent of the hub/date filters above.

Everything above is the last few months at a single trading hub. This panel is the six-year backdrop, and it is measured differently: DART at the load aggregation points (DLAP), weighted PG&E 40% / SCE 40% / SDGE 20% — the spread as the system average load actually experienced it. It is not affected by the hub and range filters above. The story is convergence: the day-ahead and real-time markets used to disagree violently and now mostly don't, as batteries absorbed the evening ramp that used to blow real-time prices past the day-ahead forecast. Each dot is one day, coloured by the hour-ending in which that day's single largest |DART| landed — violet and blue are overnight, green and amber the solar middle, orange and magenta the evening ramp. Switch to Hour of peak spread to put that hour on the vertical axis, where the shift out of the evening ramp is easiest to read.

Method. Day-ahead prices: OASIS PRC_LMP (DAM, hourly) at TH_NP15_GEN-APND / TH_SP15_GEN-APND / TH_ZP26_GEN-APND. Real-time prices: PRC_INTVL_LMP (RTM 5-minute dispatch), averaged to hour-ending — the unweighted hourly mean a 1 MW flat virtual settles against. Load: SLD_FCST for the CAISO TAC — the DAM forecast is compared against the RTPD (real-time market) forecast, not against "Total Actual Hourly Integrated Load": every OASIS forecast run (2DA/DAM/RTPD/RTD) is published net of estimated behind-the-meter solar while the actual-load series is not, a definitional gap that peaks around 8 GW midday. The DAM−RTPD revision is the same-definition demand surprise the RT market actually prices. Actual integrated load is still used for the peak-load regime classification. Wind/solar: SLD_REN_FCST DAM forecast vs. actual generation summed over trading hubs; actual generation reflects curtailment, so the solar "error" mixes forecast miss with economic curtailment — read it as "MW that didn't show up," which is what the real-time market experiences. All dates are Pacific trading days, hours are hour-ending 1–24. Backtests ignore transaction costs, bid-cost-recovery allocation, and market impact. Nothing here is investment advice.

Long-history panel. Separate series, separate price definition: DART at the three DLAPs (DLAP_PGAE-APND, DLAP_SCE-APND, DLAP_SDGE-APND) weighted 40/40/20, from the same PRC_LMP (DAM) and PRC_INTVL_LMP (RTM, averaged to the hour) reports. Days before June 2026 were seeded from the hourly day-ahead-vs-actual series behind the duck curve analysis and everything after is fetched from OASIS on the same definitions; a seven-day overlap check reproduced the seeded values to three decimals, so the seam is not a break in method. Days with fewer than 20 usable hours are dropped. The colour channel is the hour-ending containing that day's single largest |DART| — a cyclical scale that closes on itself, so HE24 and HE1 read as neighbours rather than opposites. Both this series and the hub series above refresh together in the same daily job.