Schedule batteries in Spain before the day-ahead auction

To schedule a battery for the next day, an operator must commit the plan before the 12:00 auction. The daily gap between the highest and the lowest price averages EUR 109/MWh. The forecast determines how much of this spread the battery earns.

The case covers one national price. A battery anywhere in the country sees the same price and the same forecast.

To compare forecasts on equal terms, the backtest schedules one 100 MW / 400 MWh battery on each forecast. The battery has 85% round-trip efficiency, one cycle per day, and a degradation cost of EUR 10/MWh.

The comparison includes a naive schedule that repeats the previous day and three rival foundation models that read price history only. The free public forecasts are the demand, wind, and solar forecasts published by Red Eléctrica, which a gradient-boosting model converts into a price forecast.

eomer Expert adds three agents to the eomer forecasting model. Site Agent forecasts the output of the largest solar and wind plants, Grid Agent reads the published system forecasts, and Border Agent reads interconnector capacities and neighbouring markets.

eomer Expert captures 98% of the perfect-foresight profit, compared with 98% for the free public forecasts and 96% for the most profitable rival model. eomer Expert is ahead of the most profitable rival model in 10 of 11 months and ahead of the free public forecasts in 8 of 11 months.

The 80% uncertainty interval of eomer Expert contains 75% of outcomes, compared with 48% for the public-forecast benchmark. Relative to the naive schedule, eomer Expert adds EUR 648k per battery-year.

The schedule settles at the day-ahead price without intraday updates, so the estimate excludes intraday trading and balancing markets. A deployment must add the constraints and the market access of the actual asset.