Vitreous LabsEnergy transparency

Rock Farm

16 MW, about 16 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 22 September 2026, or is labelled as an estimate.

What it is

Registered power16 MW response and reserve auction registration
Storage duration1.0 hours capacity market de-rating class
Charging zoneMid Wales and The Midlands
Connection siteShropshire
PostcodeSY8 2DS
Balancing mechanism unitnone found under the codes we search

Who owns it and who trades it

Traded byEDF Energy Limitedruns several sitesconfirmed, Elexon's register
Owned bynot published anywhere we can read
UltimatelySUSI Partners and Eelpower joint venture probable source

How we know. The register names no owner. The capacity market holds a Rock Farm agreement belonging to SUSI Storage Development UK Ltd 1.3 km away, and RCKF reads as Rock Farm.

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

Until 1 December 2025 this battery sold as EDFE-8 under EDF ENERGY CUSTOMERS LIMITED, taking £168k inside this page's year. The handover shows in the register as a new code, not a renaming, and the old page keeps its record.

What it earned

Line364 days to 22 September 2026
Balancing mechanismnot published
Response and reserve auctions auction implied£1.4m
Capacity market£104k
Three lines together£1.5m

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 at the price the agreement cleared at, before inflation uprating, so it is a floor. 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 response and reserve delivery, and its losses, together. That position is valued here at the market index for each half hour. The volumes are measured. The price is a public benchmark, not this unit's trade. The product is derived, and is shown apart from the three measured lines above. 281 days to 12 September 2026, 38 of them still provisional in Elexon's settlement runs. Method and caveats

LineMWh or £
Metered export, what crossed the meter out6,723 MWh
Metered import, what crossed the meter in8,005 MWh
Equivalent full cycles, everything sent out over one full charge420 over 281 days, 546 a year at that rate
Apparent meter to meter efficiency84%, an ordinary battery: round trip losses alone
Balancing offers accepted0 MWh
Balancing bids accepted0 MWh
Position outside balancing, export6,723 MWh
Position outside balancing, import8,005 MWh
Valued at the market index, sold£637k
Valued at the market index, bought£786k
Outside balancing, net, at the index−£149k
Balancing and outside balancing together−£149k £-12.08/kW/yr

When it moved, against when power was dear

Across every half hour this unit was metered the market index averaged £97.46. What it sent out was worth £94.72 a megawatt hour at that same index, 0.97 times the average. What it took in was worth £98.15, 1.01 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.

Checks this unit did not pass cleanly. Published anyway, because a flagged figure with its flag is more use than a blank.

  • only 281 of 364 days metered
  • the meter exceeded the 16.0 MW registration on 15 days between 2025-12-04 and 2026-05-11, peaking at 19 MW export and 23 MW import: more than this battery can do, so another asset on the same meter, a commissioning period, or a settlement run error

Where it stands

All three measured lineswhole fleet, £/kW/yr95th percentile199 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
Rock Farmthis battery161h£94.2/kW/yr
Flatworth171h£54.1/kW/yr
Gipsy Lane161h£50.3/kW/yr
Gses 1 (GSET-04)181h£42.9/kW/yr
Gses 1 (GSET-05)181h£39.8/kW/yr
Gses 1 (GSET-03)181h£31.7/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.