A battery earns from price spreads — charge cheap, discharge dear — plus frequency response, Capacity Market and Balancing Mechanism. But the GB fleet is building out fast: our settled index measured 6.4 GW active across 154 units in 2026Q3 (7.0 GW / 155 on the re-based basis now published) — its headline wholesale line is the trading position, £17.9k/MW·yr, with the measured floor £16.9k/MW·yr beside it — and our scenario set carries 12–25 GW by 2030 (18 GW central). Every new battery charges and discharges in the same hours, flattening the spreads they live on. That is cannibalisation: forecasts that ignore it overstate 2030 revenue badly, and a project financed on that number breaches its covenants.
It solves the whole system in equilibrium — the future fleet, how every battery dispatches, and the resulting prices — all at once, until they are mutually consistent. The headline output is the bias: how far a naive, price-taker forecast overstates the realistic, cannibalisation-aware number. That single figure is what protects a financing decision. It is anchored to measured revenue: recalibrated in October 2026 to our GB index, itself re-based that month on pre-registered rules, with the old basis and restated quarters published beside it.
The naive-vs-equilibrium gap, per scenario and year — the number a lender needs to see.
£/MW/yr split across wholesale arbitrage, frequency response, Capacity Market and BM.
NPV / IRR / DSCR against the 1.40× (P50) and 1.10× (P90) covenants, with P90/P50/P10 bands.
Appraise a candidate by location and duration; compare sites head-to-head; NPV tornado drivers.
An investment committee usually sees one forward curve, from one provider, with nothing independent to test it against. Run ours beside it and the disagreement becomes the diligence. And ours is graded, the misses published with the hits.
To our knowledge the only GB BESS forecast with a graded, pre-registered validation record — commitments in dated commits before outcomes were known.
Ask any forecast vendor for their graded record. The price is published too: a single-asset second opinion is a £12,000 one-off, creditable against a subscription taken within 90 days.