The best run battery earns 5.4 times what the middle of the fleet earns
Every grid scale battery in Great Britain that took a balancing instruction, ranked by what the grid operator paid it, per kilowatt, at an annual rate. Over a week, over a month, and over the year to 19 August 2026. Same market, same rules, same weather.
Balancing money arrives in bursts, which is why one ranking is not enough
What the whole fleet was paid to discharge, each day of the year to 19 August 2026. The best week any single battery has had ran at 3.5 times the best annual rate on this page. A league table over twelve months tells you which assets are well placed. A league table over seven days tells you which ones are being worked.
One bar is one day. The red bar is the busiest day of the year. Hover any bar for its date and figure.
The league
The first three windows rank on balancing, which is the only line published day by day. The fourth ranks every operating battery on all three measured lines over the year, including the ones that have never taken a balancing instruction and sell only into the reserve auctions.
What this counts, and what it leaves out
One revenue line, not four. This page ranks on the balancing mechanism alone, because it is the only line published day by day and therefore the only one that can be cut into a week. Standing ready settles monthly and the capacity market annually, so putting them in a seven day table would mean quietly spreading an annual figure across seven days and calling it performance. The operating page carries all three measured lines together, and every asset page carries them for one site.
Income, never income minus charging cost. The ranking is on what the grid operator paid the unit. A battery that charges through a balancing bid sells that energy in the wholesale market, and nothing public measures the sale, so subtracting the purchase would charge it for a cost and credit it with nothing. Ranked that way the Scottish constraint fleet finishes last for doing exactly the job it was built for. Charging cost has its own column and is never taken off the income. This is the same rule the map uses to colour a site, so the league and the map cannot disagree.
Annualised, so a week and a year can share a column. Pounds per kilowatt per year, worked out over whichever window is selected. A unit that has been on the system for less than the full year is annualised over the days it has, and the year table shows that count. A unit with fewer than 30 days is left out of the year ranking and its rate is not published, because three good days in a first week annualise to a number nobody should rank on.
Per kilowatt of what. The rate divides income by the balancing register's capacity for the unit. For twelve units the capacity market agreements matched to the site cover more de-rated megawatts than the register gives the unit, which means the plant earning the money is larger than the registration and a rate worked out on the registration is too high. Glassenbury reads 9 MW in the balancing register and holds 45 MW of de-rated agreements. Those rows divide by the larger figure and carry a dagger. It is still a floor, because de-rated megawatts are a fraction of connected ones. How the matching works
Wholesale trading is missing, for everybody. For most batteries it is the largest of the four revenue lines and nobody publishes it site by site. We publish an estimate and never add it to a measured figure. No number on this page is an asset's full income, and none of it is profit.