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Great Britain · the operating fleet

Tollgate Energy Storage

49 MW, about 49 MWh (1 hour, from the capacity market de-rating class) in Oxfordshire, Surrey and Sussex. 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 power49 MW balancing mechanism registration
Storage duration1 hour capacity market de-rating class
Charging zoneOxfordshire, Surrey and Sussex
Connection siteWelwyn Hatfield
PostcodeAL4 0NY
Balancing mechanism unitE_TOLLB-1

Who owns it and who trades it

Traded byTollgate Energy Storage Ltdconfirmed, Elexon's register
Owned byTOLLGATE ENERGY STORAGE LIMITED
Owner established fromcapacity market registered holder
UltimatelyRNK UK Investments (Tokio Marine Holdings), managed by Low Carbon confirmed source

How we know. Companies House: Tollgate Energy Storage Ltd, the company that trades the battery, is controlled at 75% or more by Tollcux Finance Ltd, which is controlled by Tollcux Investments Ltd, which is controlled by RNK UK Investments Ltd, all care of Low Carbon Ltd; RNK UK Investments is controlled by Tokio Marine Holdings since 15 May 2025, after Nippon Koei and then ID&E Holdings. Built as a Nippon Koei and Low Carbon project with TMEIC batteries.

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 systemTMEIC, battery procurement (two 49.5 MW systems, Tollgate and Cuxton)
Engineering and constructionNippon Koei Energy Europe (EMS and delivery)

From published documents, not from any register: supplier and contractor project pages, owner announcements and the trade press. Confidence: confirmed. Checked 2026-10-06. 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£110k
Response and reserve auctions auction implied£1.5m
Capacity market£374k
Three lines together£2.0m

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 a frequency response contract in 15,743 of those half hours. The energy the contract asked of it, contracted megawatts times NESO's published delivery curve at the measured grid frequency, is taken out of the position and valued at the imbalance price, because it sits outside the unit's declared position and that is the price Elexon settles it at. What remains is the traded position, valued at the market index. In 16 half hours a contract was held but the grid frequency is not yet held, so those are left in the traded position. 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 out16,528 MWh
Metered import, what crossed the meter in19,685 MWh
Equivalent full cycles, everything sent out over one full charge337 over 359 days, 343 a year at that rate
Apparent meter to meter efficiency84%, an ordinary battery: round trip losses alone
Balancing offers accepted1,041 MWh
Balancing bids accepted491 MWh
Position outside balancing, export16,133 MWh
Position outside balancing, import19,841 MWh
Of which expected response delivery, net367 MWh 1,964 out, 1,597 in
Traded position, net−4,074 MWh 15,263 out, 19,337 in
Traded position at the market index, sold£1.9m
Traded position at the market index, bought£1.5m
Traded position, net, at the index£318k
Response delivery, net, at the imbalance price£23k £32k at the index
Balancing and outside balancing together£441k £9.15/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 £122.30 a megawatt hour at that same index, 1.26 times the average. What it took in was worth £80.11, 0.82 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 491 MWh of accepted bids it paid an average of £83.09 a megawatt hour. The market index averaged £137.83 across those same half hours, so it bought back at £54.74 a megawatt hour below the going price.

Price it paidVolumeAverageCash
below zero43 MWh−£25.31£1k received
£0 to £2540 MWh£15.27£609
£25 to £5058 MWh£38.34£2k
£50 to £7549 MWh£66.63£3k
£75 to £10080 MWh£89.28£7k
above £100221 MWh£129.28£29k

On 43 MWh the price was below zero: NESO paid this unit an average of £25.31 a megawatt hour to take energy, £1k in all. That is a constrained network with more generation on it than it can move.

The other direction, offers, is much smaller here: 1,041 MWh where NESO asked for more, paid at an average of £135.92 against an index of £75.96.

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/yr8th percentile100 units
Balancing incomeEngland and Wales peer group6th percentile72 units
Balancing income1.0 hour duration cohort7th percentile30 units
All three measured lineswhole fleet, £/kW/yr57th percentile230 units
Energy sent outhours at full power9th percentile98 units
Energy taken inhours at full power2nd 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
Pillswood 2 Battery Storage501.5h£59.4/kW/yr
Tollgate Energy Storagethis battery491h£41.3/kW/yr
Cowley491.5h£30.5/kW/yr
Clay Tye Farm 1 Battery Storage501h£27.4/kW/yr
Red Scar491h£16.5/kW/yr
Wickham Market491h£6.2/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.