A day through the stack

The intraday price shape isn't data — it's the merit order read out by the day. Demand sweeps from the overnight trough to the evening peak, solar swells and dies, and each hour lands on a different rung of the same staircase: the price is flat where the stack is flat and spiky where it's steep. The gas staircase is why the evening peak costs what it does; the solar bell is why a sunny afternoon barely clears above nuclear.

The storage fleet plans like a trader with perfect foresight of the raw shape: greedy pair-matching of the cheapest charging hours against the dearest discharge hours, within its power and duration limits. But its own dispatch feeds back — charging lifts the trough, discharging shaves the peak — so the shape it actually earns on is flatter than the one it planned on. That gap is drawn (ghost shape behind, flattened shape in front) and quoted: storage flattens the very shape it feeds on, and its margin per MW falls as the fleet grows.

One representative day, cleared pay-as-clear hour by hour, inheriting the merit-order toy's named simplifications (flat bids, no unit commitment, no network). The fleet has perfect foresight of its own day — real fleets forecast, and miss; the gap between greedy and truly optimal dispatch is small at toy scale and belongs to a sibling toy. The solar bell is a shape, not weather. No live data, ever.