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Great Britain · the operating fleet

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 16 October 2026, or is labelled as an estimate.

What it is

Registered power42 MW balancing mechanism registration
Storage duration1 hour capacity market de-rating class
Charging zoneMid Wales and The Midlands
Connection siteBloxwich
PostcodeWS2
Balancing mechanism unitE_ARNKB-1

Who owns it and who trades it

Traded byOctopus Energy Trading Limitedruns several sitesconfirmed, Elexon's register
Owned byBLOXWICH ENERGY STORAGE LIMITED
Owner established fromcapacity market registered holder
UltimatelyGresham 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 systemGE (Grid Solutions era build)
Engineering and constructionGE 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

Line364 days to 16 October 2026
Balancing mechanism£499k
Response and reserve auctions auction implied£118k
Capacity market£90k
Three lines together£706k

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. 359 days to 11 October 2026, 45 of them still provisional in Elexon's settlement runs. Method and caveats

LineMWh or £
Metered export, what crossed the meter out11,302 MWh
Metered import, what crossed the meter in14,613 MWh
Equivalent full cycles, everything sent out over one full charge271 over 359 days, 276 a year at that rate
Apparent meter to meter efficiency77%, plausible: losses plus a standing load that is material against a modest throughput
Balancing offers accepted6,242 MWh
Balancing bids accepted4,411 MWh
Position outside balancing, export9,849 MWh
Position outside balancing, import14,991 MWh
Valued at the market index, sold£1.2m
Valued at the market index, bought£1.2m
Outside balancing, net, at the index£447
Balancing and outside balancing together£484k £11.80/kW/yr

When it moved, against when power was dear

Across every half hour this unit was metered the market index averaged £97.34. What it sent out was worth £125.69 a megawatt hour at that same index, 1.29 times the average. What it took in was worth £82.55, 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 4,411 MWh of accepted bids it paid an average of £62.14 a megawatt hour. The market index averaged £97.37 across those same half hours, so it bought back at £35.23 a megawatt hour below the going price.

Price it paidVolumeAverageCash
below zero422 MWh−£19.26£8k received
£0 to £25425 MWh£13.91£6k
£25 to £50765 MWh£39.35£30k
£50 to £751,140 MWh£62.87£72k
£75 to £100854 MWh£85.99£73k
above £100805 MWh£125.58£101k

On 422 MWh the price was below zero: NESO paid this unit an average of £19.26 a megawatt hour to take energy, £8k in all. That is a constrained network with more generation on it than it can move.

The other direction, offers, is much smaller here: 6,242 MWh where NESO asked for more, paid at an average of £121.36 against an index of £81.47.

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/yr46th percentile100 units
Balancing incomeEngland and Wales peer group37th percentile72 units
Balancing income1.0 hour duration cohort72nd percentile30 units
All three measured lineswhole fleet, £/kW/yr34th percentile230 units
Energy sent outhours at full power60th percentile98 units
Energy taken inhours at full power31st percentile98 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.

BatteryMWHoursMeasured, per kW
Minety (AG-HLIM04)441h£45.2/kW/yr
Hunningley Stairfoot BESS441h£37.8/kW/yr
Gses 1 (GSET-07)451h£37.5/kW/yr
Halesworth401h£18.5/kW/yr
AR0006-BLOXthis battery421h£17.0/kW/yr
Stairfoot401.5h£10.1/kW/yr

See it on the map

Open the operating map here

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.