AR0006-BLOX
42 MW, about 42 MWh (1 hour, from the capacity market de-rating class) in Mid Wales and The Midlands. Everything on this page is read from published data for the 364 days to 27 September 2026, or is labelled as an estimate.
What it is
| Registered power | 42 MW balancing mechanism registration |
| Storage duration | 1 hour capacity market de-rating class |
| Charging zone | Mid Wales and The Midlands |
| Connection site | Bloxwich |
| Postcode | WS2 |
| Balancing mechanism unit | E_ARNKB-1 |
Who owns it and who trades it
| Traded by | Octopus Energy Trading Limitedruns several sitesconfirmed, Elexon's register |
| Owned by | BLOXWICH ENERGY STORAGE LIMITED |
| Owner established from | capacity market registered holder |
| Ultimately | Gresham House Energy Storage Fund confirmed source |
How we know. The registered office of each company names Gresham House Asset Management, read company by company on 31 August 2026. The address alone would not settle it, because 875 companies sit at 5 New Street Square; the care of line naming the manager is the discriminator.
Market registers name the party that sells into the market, which for a battery is usually an optimiser under contract rather than the owner. Elexon's balancing mechanism unit register names the seller here and the name is checked against it on every build. How we tell them apart
What it is built from
| Battery system | GE (Grid Solutions era build) |
| Engineering and construction | GE UK Grid Solutions, main contractor for Arenko; Alpha Construction adapted the existing industrial building |
From published documents, not from any register: supplier and contractor project pages, owner announcements and the trade press. Confidence: confirmed. Checked 2026-08-31. source 1. Fields not shown are not published anywhere we have found, and we do not guess them.
What it earned
| Line | 364 days to 27 September 2026 |
|---|---|
| Balancing mechanism | £509k |
| Response and reserve auctions auction implied | £134k |
| Capacity market | £93k |
| Three lines together | £736k |
Balancing is offer revenue and does not net off the cost of the power. The response and reserve figure is the value implied by the published auction results, award quantity times clearing price times the length of the delivery window, and not a settled payment. Capacity market income is the cleared price raised for inflation where the auction set a base period, split by month on EMRS's weights. Method
Outside the balancing mechanism, derived from the meter
Elexon publishes what this unit's meter recorded every half hour. Take away the balancing volumes NESO accepted and what is left is the position the unit ran outside the balancing mechanism: its wholesale trading, its frequency response delivery, and its losses, together. This unit held no frequency response contract in the window, so the whole position is treated as traded. The volumes are measured. The prices are public benchmarks, not this unit's trades. The product is derived, and is shown apart from the three measured lines above. 346 days to 12 September 2026, 33 of them still provisional in Elexon's settlement runs. Method and caveats
| Line | MWh or £ |
|---|---|
| Metered export, what crossed the meter out | 10,638 MWh |
| Metered import, what crossed the meter in | 13,774 MWh |
| Equivalent full cycles, everything sent out over one full charge | 255 over 346 days, 269 a year at that rate |
| Apparent meter to meter efficiency | 77%, plausible: losses plus a standing load that is material against a modest throughput |
| Balancing offers accepted | 5,932 MWh |
| Balancing bids accepted | 3,884 MWh |
| Position outside balancing, export | 9,193 MWh |
| Position outside balancing, import | 14,377 MWh |
| Valued at the market index, sold | £1.1m |
| Valued at the market index, bought | £1.1m |
| Outside balancing, net, at the index | −£86k |
| Balancing and outside balancing together | £401k £10.14/kW/yr |
When it moved, against when power was dear
Across every half hour this unit was metered the market index averaged £93.43. What it sent out was worth £115.03 a megawatt hour at that same index, 1.23 times the average. What it took in was worth £79.54, 0.85 times. Selling above one and buying below one is a unit positioned into the dear half hours and out of the cheap ones. It measures the half hours it chose, not the price anyone paid it, which is not published.
What it paid to buy energy back
When NESO accepts a bid, this unit delivers less than it had already sold, or takes more in. It pays for the energy it no longer delivers, and that payment is most of what makes the balancing figure above negative. Whether that is a cost or a margin depends on the price it paid. Across 3,884 MWh of accepted bids it paid an average of £52.94 a megawatt hour. The market index averaged £86.29 across those same half hours, so it bought back at £33.35 a megawatt hour below the going price.
| Price it paid | Volume | Average | Cash |
|---|---|---|---|
| below zero | 470 MWh | −£18.13 | £9k received |
| £0 to £25 | 406 MWh | £14.92 | £6k |
| £25 to £50 | 769 MWh | £39.44 | £30k |
| £50 to £75 | 1,166 MWh | £62.43 | £73k |
| £75 to £100 | 708 MWh | £86.11 | £61k |
| above £100 | 365 MWh | £120.40 | £44k |
On 470 MWh the price was below zero: NESO paid this unit an average of £18.13 a megawatt hour to take energy, £9k in all. That is a constrained network with more generation on it than it can move.
The other direction, offers, is much smaller here: 5,932 MWh where NESO asked for more, paid at an average of £116.72 against an index of £79.42.
Physical checks passed: the meter never exceeded the registered power by more than fifteen per cent, and the year's exports against imports are what a battery does.
Where it stands
| Balancing incomewhole fleet, £/kW/yr | 51st percentile98 units | |
| Balancing incomeEngland and Wales peer group | 38th percentile70 units | |
| Balancing income1.0 hour duration cohort | 83rd percentile24 units | |
| All three measured lineswhole fleet, £/kW/yr | 37th percentile229 units | |
| Energy sent outhours at full power | 59th percentile96 units | |
| Energy taken inhours at full power | 29th percentile96 units |
Percentiles, so 90 means better than nine in ten of the cohort named beside it, on that measure alone, over the same 364 days. Rates are pounds per kilowatt per year, annualised over the days the unit has been on the system, the same figures the performance league ranks on. A high position in the taken-in table is not a fault: a constraint asset is paid to charge, and charging is its job.
The nearest comparables
The five nearest in size in England and Wales, and this battery among them, ranked by what each was paid for every kilowatt it holds over the 364 days to the same date. They run for about the same length of time. Same market, same rules, same weather.
| Battery | MW | Hours | Measured, per kW |
|---|---|---|---|
| Gses 1 (GSET-07) | 45 | 1h | £41.9/kW/yr |
| Hunningley Stairfoot BESS | 44 | 1h | £37.0/kW/yr |
| Minety (AG-HLIM04) | 44 | 1h | £36.3/kW/yr |
| AR0006-BLOXthis battery | 42 | 1h | £17.7/kW/yr |
| Halesworth | 40 | 1h | £12.3/kW/yr |
| Stairfoot | 40 | 1.5h | £10.0/kW/yr |
See it on the map
Every figure on this page traces to a published file. If something here is wrong about your asset, the methods section says how to tell us.