Provisional — figures revise at settlement runs
Every figure here is computed on initial-settlement data: the first pass at the numbers by Elexon, the body that settles Britain's electricity market. Later settlement runs move the figures. This page is a pulse; the settled quarterly report is the record. Basis id: section17_rebased.
What you are looking at
Revenue per megawatt of grid battery in Great Britain, for each calendar month and for the last 30 days. £/MW·yr is pounds per megawatt of battery per year, before operating costs. It is a fleet figure, not any one site's.
The split shows where the money came from. Wholesale is buying power when it is cheap and selling it when it is dear. The Balancing Mechanism is the grid operator paying batteries to change what they are doing at short notice. Frequency response is being paid to stand ready to steady the grid's frequency. The Capacity Market, an annual contract to be available when the system is tight, sits beside the monthly total rather than inside it; the reason is a few lines down.
What it is not
Not the settled record; the quarterly report is. And not a forecast or an appraisal of any one site; to model a site forward, open the New Site appraisal in the app.
Why wholesale appears twice
The headline is the trading position: what each battery declared it would do, valued at the auction price for that hour, with any gap between the declaration and what it actually delivered valued at the grid's imbalance price. Beside it is the floor, marked ᶠ: the same metered energy valued at Elexon's within-day market index, net of balancing volumes. The floor is deliberately cautious and never comes off the page. Where a month publishes the trading position, that basis gives the month's headline total, highlighted, with the floor-basis total beside it; otherwise the floor leads and the trading-position cells show a dash (hover for why).
Read this page for the shape of the month. For the number itself, go to the quarterly report; that is the one I sign off.
About the Capacity Market column
The Capacity Market is an annual contract. Its Settlement Body pays it out monthly on a weighting of its own, and nothing settles what a given month was worth. So we spread the year's sum per day and show it as an accrual beside the monthly streams. The data file's own label for that column: Capacity Market ACCRUAL — the annual obligation revenue accrued per day of the delivery year; not a monthly settlement (the Settlement Body pays by its own monthly weighting); PROVISIONAL. The three monthly streams make the headline total. A total including the accrual is printed beside it, on the floor basis. These are our conventions, not the regulated benchmark's; the quarterly report shows the difference step by step, and a CE month is never to be set beside a benchmark month.
Basis section17_rebased: the quarterly report's published rules, applied month by month on initial-settlement data.
Loading the provisional series…
Settled and provisional. Elexon settles the market in passes: a quick first pass, then corrections, sometimes months on. This page uses the first pass, so its figures move, and the settled quarterly report is the record: this series is computed on initial-settlement data and revises at later settlement runs. Provisional points are never restated silently: each refresh re-emits the full series with its computation date, and the settled quarterly report supersedes this page. Basis. The series follows the rules the quarterly report publishes, listed on the public protocol record. When they change, the outgoing basis stays published beside the new one for at least four quarters and a switch appears above; every view names the basis it shows. Why the Balancing Mechanism can be negative. In a month when batteries paid more for the energy they were instructed to take on than they were paid for the energy they put out on instruction, the net is negative. That energy is netted out of the wholesale floor, so it counts once, and the month's total is the net of everything. The older, outgoing series still carries the double count; it stays published beside this one for continuity.