Shilton Lane BESS
40 MW, about 80 MWh (2 hours, measured from its behaviour) in South West Scotland. 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 | 40 MW balancing mechanism registration |
| Storage duration | 2 hours measured from twenty one days of behaviour |
| Charging zone | South West Scotland |
| Connection site | Renfrewshire |
| Postcode | PA8 6HH |
| Balancing mechanism unit | E_SHILB-1 |
Who owns it and who trades it
| Traded by | Octopus Energy Trading Limitedruns several sitesconfirmed, Elexon's register |
| Owned by | not published anywhere we can read |
| Ultimately | Gresham House Energy Storage Fund confirmed source |
How we know. The register names no owner. Gresham House bought the 40 MW Shilton Lane project near Glasgow in 2022, and the capacity market holds three Shilton agreements at that location belonging to Gresham House Energy Storage Holdings plc.
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
| Engineering and construction | Jones Bros Civil Engineering (principal civils); Nairn Construction, bases and ducting |
| Entered operation | 2026-07 |
| Container count | civils scale: over 1,200 m3 of reinforced concrete bases, 4,000 m of cable ducting (counts of units not published) |
From published documents, not from any register: supplier and contractor project pages, owner announcements and the trade press. Confidence: confirmed. Checked 2026-08-30. source 1 · source 2. 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 | £45k |
| Response and reserve auctions auction implied | £43k |
| Capacity market | no agreement we can attach |
| Three lines together | £88k |
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 | 15,978 MWh |
| Metered import, what crossed the meter in | 19,080 MWh |
| Equivalent full cycles, everything sent out over one full charge | 200 over 346 days, 211 a year at that rate |
| Apparent meter to meter efficiency | 84%, an ordinary battery: round trip losses alone |
| Balancing offers accepted | 1,368 MWh |
| Balancing bids accepted | 5,248 MWh |
| Position outside balancing, export | 17,484 MWh |
| Position outside balancing, import | 16,706 MWh |
| Valued at the market index, sold | £2.1m |
| Valued at the market index, bought | £1.3m |
| Outside balancing, net, at the index | £752k |
| Balancing and outside balancing together | £798k £21.04/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 £120.03 a megawatt hour at that same index, 1.28 times the average. What it took in was worth £80.58, 0.86 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 5,248 MWh of accepted bids it paid an average of £29.14 a megawatt hour. The market index averaged £87.25 across those same half hours, so it bought back at £58.11 a megawatt hour below the going price.
| Price it paid | Volume | Average | Cash |
|---|---|---|---|
| below zero | 928 MWh | −£21.20 | £20k received |
| £0 to £25 | 1,388 MWh | £11.52 | £16k |
| £25 to £50 | 1,803 MWh | £35.38 | £64k |
| £50 to £75 | 574 MWh | £60.56 | £35k |
| £75 to £100 | 263 MWh | £85.92 | £23k |
| above £100 | 292 MWh | £121.45 | £35k |
On 928 MWh the price was below zero: NESO paid this unit an average of £21.20 a megawatt hour to take energy, £20k in all. That is a constrained network with more generation on it than it can move.
The other direction, offers, is much smaller here: 1,368 MWh where NESO asked for more, paid at an average of £144.97 against an index of £109.72.
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 | 15th percentile98 units | |
| Balancing incomeScotland peer group | 30th percentile28 units | |
| Balancing income2.0 hour duration cohort | 12th percentile61 units | |
| All three measured lineswhole fleet, £/kW/yr | 16th percentile229 units | |
| Energy sent outhours at full power | 20th percentile96 units | |
| Energy taken inhours at full power | 35th 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 Scotland, 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 |
|---|---|---|---|
| Wishaw BESS | 51 | 2h | £44.7/kW/yr |
| Auchteraw | 49 | 2h | £33.3/kW/yr |
| Erskine BESS | 30 | 2h | £11.1/kW/yr |
| East Ayrshire (KILSB-2) | 52 | 2h | £3.1/kW/yr |
| East Ayrshire (KILSB-1) | 53 | 2.1h | £3.0/kW/yr |
| Shilton Lane BESSthis battery | 40 | 2h | £2.2/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.