UK BESS Queue Fee (CMP470): Costs, Co-location and Dates

What CMP470 Would Change

Today a battery project's financial commitment to its grid connection builds up late. Developers post securities against cancellation charges, and the amounts grow as energisation approaches. The trigger date, when larger securities start, is generally 1 April three financial years before a project connects.

CMP470 adds a floor under that. It was raised on March 20, 2026 by developer Field Energy and is called the Oversubscribed Technologies Commitment Fee, or OTCF. Where a project's cancellation charge or secured amount sits below the floor, it is topped up to the floor. Projects already above it pay nothing extra.

The rules that matter most:

• Who: projects with a Gate 2 place in a technology that is oversubscribed, whether connected to the transmission or the distribution network. At present that means batteries only. Demand projects are excluded.
• When it switches on: when a technology's total capacity (operating, plus Gate 2 offers signed or confirmed) is more than 50% over its target in the government's Clean Power 2030 plan, and the target itself is above 5 GW. It switches off when the figure falls below 25%.
• How long it lasts: from Gate 2 offer acceptance until the project energises.
• How it steps up: it starts at £3,000 per MW. Before each six-monthly securities statement, NESO checks the queue. If oversubscription has not fallen by at least 25% since the last check, the floor rises to £5,000 per MW and then by £5,000 per MW each time, to a maximum of £25,000 per MW.
• Discretion: NESO may choose not to switch the fee on or not to raise it, and Ofgem can overrule that. Neither can switch it on or raise it when the thresholds are not met.

This is an illustration, not a forecast. It assumes the fee switches on in the July 2027 statement and that oversubscription never falls by 25% in a review period.

Why Ofgem Thinks It Is Needed

The numbers behind CMP470 are stark. About 7 GW of battery storage is operating and roughly 83 GW has Gate 2 status, around 90 GW in all. Ofgem puts the need at 23 to 27 GW by 2030 and 24 to 29 GW by 2035. NESO estimates another 20.9 GW of protected batteries could qualify in the next application window, which would take the total to about 111.5 GW.

Only batteries are above the 50% line. The figures come from NESO's connections reform results as quoted in the Final Modification Report, and they will move as offers are signed or lapse.

Ofgem's argument is about timing. NESO and the transmission owners must plan and build as if every Gate 2 project will connect, so unviable projects can hold up viable ones and push network spending onto consumers. Ofgem's impact work estimates at least £460 million of inefficient network costs if all current projects were to leave the queue. It says the question is not whether projects will drop out, but whether they do so early enough to inform network plans.

Its evidence is that commitment is currently light:

• About 58% of battery capacity has not yet reached its trigger date and faces little or no liability.
• Only around 16% has both passed the trigger date and secured planning consent.
• More than 25% of projects have no securities exposure, and about 89% have posted less than £3,000 per MW.
• Half of projects have posted under £800 per MW and carry about £1,500 per MW of liabilities. Projects being commissioned in 2027 have posted about £5,600 per MW and carry £12,200 per MW.

Market forecasts cited in the Final Modification Report suggest the GB battery market can support only about 15 to 30 GW by 2035, well below the queue.

What It Would Cost a Project

The fee is a minimum, so the extra cash depends on what a project has already posted. The table shows the most a project would need to hold at each step if it had posted nothing.

The figures are simple multiplication of the per MW floor by project size.

Ofgem puts the initial level at about £230 million of extra security across affected projects, and the securities come back when a project connects. It sees the main effect as financing and liquidity pressure, not an equal increase in spending. At the maximum level, the fee would equal roughly a quarter of capex for a short-duration battery and just over 7% for a medium-duration one.

The breadth is large. The Original Proposal would raise liabilities for about 78% of projects at the start and up to 97% at the maximum.

Co-Located Solar and Battery Sites

Co-location is where solar EPCs should look closest. A project is exempt if all three conditions hold:

• The oversubscribed technology connects after the other technology.
• It adds no Transmission Entry Capacity (TEC), the export capacity the site is allowed.
• It adds less than £250,000 of attributable works and connection costs.

If a co-located site does not qualify, the fee applies to the lower of the battery's installed MW and the site's total TEC. For example, a 100 MW battery sharing a 100 MW connection with 100 MW of solar pays on 100 MW. Staged projects pay on the capacity not yet energised. If two technologies were ever both over the line, only the higher £ per MW rate would apply.

The scale of the exemption is limited. Of 82.8 GW of Gate 2 batteries, 52.8 GW are standalone, 21.3 GW connect first or at the same time as another technology, and 8.7 GW connect after another technology. In 2.7 GW of that last group the battery is larger than the first technology. The workgroup concluded the exemption could cover at most about 6 GW and probably less.

One workgroup alternative, WACM4, would remove the exemption. Ofgem is not minded to adopt it, saying it has not seen enough evidence that the extra reach brings extra benefit.

Solar-only projects are not in scope. Solar is only 1.2% over its target, far from the 50% line, although the proposer estimates a further 4 GW could be protected in future application windows.

The Alternatives Ofgem Did Not Pick

The workgroup produced six alternatives to the Original Proposal. Ofgem's provisional view is that the Original Proposal best meets the code objectives.

Industry is split. The workgroup majority backed the Original Proposal and WACM4. Network companies mostly wanted stronger intervention. Many developers accepted there is an oversupply but argued for more time for natural attrition, and warned that the fee could favour better-capitalised developers. Ofgem says it has not seen evidence that competition would be materially distorted.

Key Dates

• March 20, 2026: Field Energy raises CMP470, which is handled on an urgent basis.
• July 14, 2026: NESO sends the Final Modification Report to Ofgem.
• September 17, 2026: Ofgem publishes its minded-to position to approve the Original Proposal.
• October 1, 2026: the consultation closes. Ofgem's page lists it as closed, awaiting a decision, and gives no decision date.
• After the decision: the change would enter the code 10 business days later, but the fee would not be live yet.
• Activation: after the Gate 2 offers from the connections reform process are signed or lapse and the first new application window is settled. The current assumption is the July 2027 securities statement, with payments from October 2027. NESO's June timeline had the final Gate 2 offers going out in January and March 2027, due for signature in April 2027, so check for changes.

What This Means for Storage and Solar EPCs

Five practical points follow from the documents.

First, expect pipeline attrition. The purpose of the fee is earlier exits, and Ofgem's own impact work says every fee option would help remove low-commitment projects. Some battery projects in an EPC's pipeline may not proceed.

Second, ask clients about their security position. The fee lands before any revenue, and Ofgem accepts that liquidity will matter for some developers. Whether a client holds, sells or exits a Gate 2 place before the fee activates can change a project's timing.

Third, for co-located sites, connection order and TEC are now commercial variables. Whether a battery connects second without adding export capacity, and what the extra connection work costs, can decide whether the fee applies. This needs checking against the client's connection offer.

Fourth, solar-only work is not affected. The fee follows technologies, and solar is nowhere near the threshold.

Fifth, treat the details as provisional. Ofgem has said it is open to further evidence and the design could change before a final decision.

Where Design Software Fits

On a co-located site, staging and the amount of connection work can decide whether the fee applies. Design software like Reslink produces the layout, bill of materials and single line diagram for the solar side, and supports ground-mount feasibility up to 1 GW, so staging options can be compared on one set of site assumptions. It does not model grid securities or queue outcomes.

See the full workflow → Book a demo

Frequently Asked Questions

Q1. What is CMP470?

A proposed change to the Connection and Use of System Code that would create a minimum financial commitment for projects in technologies whose grid queue is far larger than the government's targets. It was raised by Field Energy.

Q2. Has Ofgem made a final decision?

No. Ofgem published a minded-to position to approve the Original Proposal on September 17, 2026 and closed the consultation on October 1. It has not published a final decision or given a date.

Q3. Which projects would pay?

Battery projects with Gate 2 status, connected to the transmission or distribution network, from accepting their Gate 2 offer until they energise. This holds only while batteries remain more than 50% over their target.

Q4. What happens to the money?

The securities are returned when a project energises. If a project cancels, the charge including the fee is paid, and the fee element goes back to consumers through transmission network charges.

Q5. When would payments start?

Under current assumptions the fee would first appear in the July 2027 securities statement, with payments from October 2027. That depends on the Gate 2 offer process finishing on time.

Q6. Does it apply to solar-only projects?

No. Solar is about 1.2% over its target, well below the 50% trigger, and the fee applies only to technologies above it.

Q7. What does Gate 2 mean?

It is the status given to projects that pass the readiness and strategic need tests under connections reform. A Gate 2 project holds a contract to connect on a set date and is liable for cancellation charges if it withdraws.

Final takeaway

The proposed fee is small at the start and large at the cap, and it is aimed at one technology. For storage EPCs the near-term question is how many battery projects in the queue are still there once the fee bites. For solar EPCs it is how the co-location exemption treats a battery added to an existing connection.

You May Also Like

• UK NFCC BESS Guidance 2026: What's Confirmed and What's Open
• UK CfD AR8 2026: Gate 1 vs Gate 2 Solar EPC Guide
• US Interconnection Queue 2026: Solar and Storage Wait Times

Sources

• Ofgem, Minded-to Consultation: CUSC CMP470, Introducing an Oversubscribed Technologies Commitment Fee (September 17, 2026)
• National Energy System Operator, CMP470 Final Modification Report (July 14, 2026)
• National Energy System Operator, CMP470 modification page and documents (updated July 14, 2026)

This guide reflects Ofgem's minded-to consultation and NESO's Final Modification Report as of October 27, 2026. Ofgem's final decision and NESO's connections timeline may change what applies, so check both before relying on a date or figure.