A battery in North Scotland is turned down thirty three times as often as it is turned up
Elexon publishes every accepted bid and offer in the balancing mechanism with the price it was accepted at. Reading a full year of it, unit by unit, across 4,685 MW of the 4,814 MW that traded at all, shows that a battery in Scotland and a battery in the Midlands are doing two different jobs.
| Where | Placed | Turned up | Turned down | Ratio | Offer revenue |
|---|---|---|---|---|---|
| Scotland | 1,580 MW | 48 h/y | 373 h/y | 7.8x | £5.67/kW/y |
| England and Wales | 3,214 MW | 322 h/y | 249 h/y | 0.8x | £34.71/kW/y |
Measured as full power hours a year, weighted by registered capacity so a large unit is not one vote. England and Wales earns 6.1 times what Scotland earns for each kilowatt installed.
What turned up and turned down actually mean
Volume in the balancing mechanism is measured against the unit's own physical notification, not against zero. A battery that has told the system it will charge at 57 MW, and is then instructed to sit at plus 57 MW instead, books a 114 MW upward deviation even though it spent part of that time simply not charging. So turned up covers discharging and charging less, and turned down covers charging and discharging less.
This also sets the arithmetic ceiling. A unit can swing from full charge to full discharge, so the most it can book in half an hour is its registered megawatts expressed in megawatt hours, not half of that. Every unit in the set was tested against that ceiling and one exceeded it, by five per cent, which is within the tolerance of a rounded registration figure.
It is a gradient, not a border
Split by charging zone rather than by country, the pattern is continuous and it runs north to south.
| Charging zone | MW | Up h/y | Down h/y | Ratio | £/kW/y |
|---|---|---|---|---|---|
| North Scotland | 209 | 43 | 1,407 | 32.8x | £5.08 |
| Eastern Grampian and Tayside | 125 | 58 | 794 | 13.7x | £6.30 |
| Stirlingshire and Fife | 250 | 78 | 392 | 5.0x | £8.91 |
| South West Scotlands | 433 | 75 | 184 | 2.4x | £9.22 |
| Lothian and Borders | 563 | 13 | 34 | 2.5x | £1.59 |
| North East England | 95 | 204 | 335 | 1.6x | £23.24 |
| Oxfordshire, Surrey and Sussex | 224 | 382 | 436 | 1.1x | £41.75 |
| Essex and Kent | 769 | 334 | 222 | 0.7x | £36.32 |
| Mid Wales and The Midlands | 612 | 409 | 281 | 0.7x | £43.38 |
| South Lancashire, Yorkshire and Humber | 686 | 410 | 285 | 0.7x | £43.62 |
North Scotland is the extreme. The four Blackhillock units spent 1,407 full power hours a year being held down and 43 being called up, and were paid £5.08 for each kilowatt of registered capacity. Assets in Mid Wales and the Midlands were paid £43.38 for the same kilowatt, eight times as much, for doing the opposite thing.
Three corrections are folded into the figures above. The largest: NESO publishes a postcode with every ancillary auction result, and checking our positions against it found six units at Kilmarnock South, 300 MW between them, sitting 257 km away in Lancashire. Moving them into Ayrshire where they belong changed both sides of this comparison. An earlier version reported six times, and £10.15 against £24.73, calculated on 2,406 MW because the rest of the fleet carried no coordinate; placing Blackhillock, Coalburn, Whitelee, Neilston and Cathkin trebled Scotland's mapped capacity and widened the gap. Separately, the per unit money had been computed over 2025-08-10 to 2026-08-08 while every page printed 2025-08-21 to 2026-08-19. Thirty five of ninety four units carried a figure for the wrong window. Everything here is now computed once, on the window it declares.
What the system is using the asset for
In Scotland the balancing mechanism is using batteries as a sink for wind that cannot get south. In England it is calling them up as a resource and paying them to deliver. The same equipment, two different jobs, decided by which side of the constraint it sits.
That sits underneath a fact about the queue: roughly three quarters of the Gate 2 storage book is Scottish, and Scotland's operating assets are currently earning an eighth of what an English one earns. Whether that is a mispricing or a correct read of a future in which the Scottish constraint is worth more than the English one is a commercial judgement. The tool presents both and resolves neither.
The number is one revenue line, not profit
A battery charges through balancing bids and sells that energy in the wholesale market. The cost leg shows in this data and the income leg does not, so net balancing cash is negative for many assets and that is a purchase rather than a loss. Offer revenue, what the system paid to have the asset discharge, is the clean comparable figure and it is the one reported.
How it was checked before it was published
Summing every unit in the market for 6 to 8 August 2026 gives £43.66m against NESO's published balancing cost of £44.83m for the same three days, a ratio of 0.97. The 3% gap is the non balancing mechanism services NESO's total includes and the settlement stack does not. Across the full year the market paid £2,682m in balancing offers, of which batteries took £227.9m, 8.5%.