Commercial battery storage in Wales

The quick answer

Commercial battery storage in Wales is priced by whichever network your site connects to. In the south that is National Grid Electricity Distribution (South Wales), whose 2026/27 weekday red band lasts two and a half hours, from 17:00 to 19:30, at 12.885p/kWh on a low-voltage Site Specific tariff, with amber charged for part of every weekend. North Wales is SP Energy Networks' SP Manweb area, with its own charging statement. No grant we can source funds a standalone business battery in Wales: the Development Bank of Wales Green Business Loan names solar PV and heat pumps, not batteries, and the Ynni Cymru grant is closed. Plant that stores power from renewable sources is outside business rates in Wales until 31 March 2035, which clearly covers a battery fed by on-site solar and leaves a grid-charged battery as a question for a rating adviser.

The South Wales red band in 2026/27

National Grid Electricity Distribution (South Wales) plc publishes a schedule of charges for every charging year. The 2026/27 schedule, marked Final and effective from 1 April 2026, sets these time bands and unit rates for half-hourly metered premises:

On the LV tariff the red unit rate is more than 62 times the green rate, so almost every red-band unit a battery covers is a unit bought back overnight for a fraction of the price. Set against the East Midlands licence area, where the red band runs for three hours at 7.777p, the South Wales red rate is about two-thirds higher and the band is half an hour shorter. That combination shapes the battery: covering 2.5 hours at full output needs less stored energy for each kW of peak removed, and each unit it moves is worth more.

Weekends are not a free-for-all either. South Wales charges amber for six hours on Saturdays and Sundays, at 0.989p on LV. That is small next to the red rate and rarely decides a business case, but a seven-day site should plan its charging around the green hours rather than treating the whole weekend as cheap.

Worked arithmetic on the published rates, not a forecast. Hold 150 kW off the grid through the whole red band on each of 261 weekdays and the battery moves 97,875 kWh a year out of red. At 12.885p that is £12,611 of distribution unit charges avoided before losses. The same 150 kW in the East Midlands, over its three-hour band at 7.777p, moves 117,450 kWh and avoids £9,134. Few sites peak on every weekday, so count your own red-band days first. The peak shaving calculator opens with the South Wales rates loaded and takes your own peak, battery size and tariff, and our DUoS charges guide explains how these rates reach a bill.

Capacity charges in South Wales

The same schedule charges 10.49p per kVA per day for agreed capacity on LV Site Specific, which is £38.29 per kVA a year, and bills any kVA above the agreed figure in a month at the same rate. On HV the capacity rate is 10.43p. The East Midlands equivalent is 7.68p, so unused headroom costs more in South Wales: a site carrying 100 kVA of agreed capacity it never draws pays about £3,829 a year for it. A battery can only turn that into a saving if it trims the peak consistently enough for the network operator to agree a lower capacity, and a month over the new figure brings the exceeded-capacity charge back. Our guide on whether a battery can reduce your kVA capacity charge sets out when that is realistic.

North Wales: the SP Manweb area

North Wales is served by SP Energy Networks through its SP Manweb licence area, which also takes in Merseyside and has around 1.5 million customers. SP Manweb sets its own time bands and unit rates in its own Use of System charging statement, and we have not read its 2026/27 statement from a primary copy, so this page quotes no North Wales rate. Take the bands and rates from your DUoS statement or SP Energy Networks' charging statement and enter them in the calculator's "Another area" option. Do not assume which operator you are on from a map of mid-Wales: the distributor ID at the start of the MPAN core settles it, and our guide to finding your network operator shows where to read it.

Connecting a battery in Wales

With either operator, battery storage above 16 A per phase goes through a G99 application, and the operator has to approve it before the battery is connected; the lighter G98 notification route is only for installations at or below that limit. A business battery is almost always a G99 case. One transmission rule changed in May 2025: under NESO's CMP446 modification, the size at which a distribution connection in England or Wales needs a Transmission Impact Assessment rose from 1 MW to 5 MW where there are no fault-level issues. Scotland kept much lower thresholds, 200 kW on the mainland and 50 kW on the islands, so connection advice written for a Scottish site does not carry over. Our G99 application guide covers what the application asks for; survey, installation and commissioning are matters for the installer and are not covered on this site.

Solar-plus-storage in Wales

Where a battery is paired with a roof array, it is sized from the midday surplus that array spills. The European Commission's PVGIS model (version 5.3, SARAH3 radiation data, 14% system losses) gives these modelled long-term averages per kWp installed. They are averages, not guarantees, and an east-west or building-integrated layout will produce less.

Planning works differently from England. Roof solar on non-domestic buildings in Wales falls under Part 43, Class A of the General Permitted Development Order as it applies in Wales, not the English Part 14. Its conditions include a maximum projection of 20 cm on walls and pitched roofs, no more than 1 m above a flat roof, nothing within 1 m of the roof edge, no installation within 3 km of an aerodrome (added in 2019), and nothing within the curtilage of a listed building. We found no permitted-development class for batteries in Part 43, so ask the local planning authority before placing an outdoor battery cabinet or container. Exported solar power can be paid under the Smart Export Guarantee, which applies across Great Britain; each supplier sets its own rate. How storage and an array work together is on our solar battery storage page.

Business rates on a battery in Wales

Wales has its own rule. The Welsh regulations made as SI 2023/1229 except from valuation the plant used to generate, store, transform or transmit power where the source is mainly or exclusively one on a list that includes photovoltaics, wind, hydro and heat from air, water or ground. The exception runs from 1 April 2024 to before 1 April 2035. A battery storing power from an on-site solar array is the clear case. A battery bought to shave peaks and charged from the grid is not obviously renewable-sourced, so treat its rating as a valuation question for your rating adviser rather than assuming it is exempt. The tax side, including the Annual Investment Allowance and VAT at 20% for a business, is in our guide to VAT, capital allowances and business rates on a battery.

Funding in Wales, realistically

Development Bank of Wales Green Business Loan Scheme. The scheme is live. It offers discounted fixed interest, capital repayment holidays at the start and a term linked to the project's payback, and the Welsh Government topped it up to £20m with funding available until 2028. A Senedd written answer (WQ96151, April 2025) puts loans at £1,000 to £1.5m over up to 15 years. It is for limited companies, sole traders and partnerships based in Wales that have traded for two years or more and filed at least one set of accounts. Its page lists solar PV, heat pumps, HVAC, fabric, LED lighting and controls, says the list is not exhaustive, and does not mention batteries, so ask the Bank whether a battery qualifies before you build a plan on it. The same scheme part-funds an energy audit, at up to 50% of the cost with a £10,000 maximum.

Ynni Cymru is closed. The 2026/27 round of the Welsh Government's capital grant closed to applications at 12pm on 21 May 2026, and no later round has been announced. Its guidance required low-carbon heat as well as renewable generation, made solar PV plus battery storage on its own ineligible, and asked SMEs for 25% match funding. The Welsh Government lists 24 awards worth £8,262,722.90.

Business Wales gives advice and runs the voluntary Green Growth Pledge; we found no Business Wales grant for solar or batteries, and its Future Proofing Fund was a 2024-25 round that has closed. Public bodies can look at Salix's Wales Funding Programme, which lends at a fixed 2.45%, with an interest-free Invest to Save route for bodies that cannot borrow; the programme page does not say whether batteries are eligible.

The UK-wide picture, and the routes that work without a grant, are on our funding and tax page.

Why the Welsh grid makes flexibility matter

The Welsh Government's first combined Energy Generation and Use in Wales report (August 2026) shows a system that generates far more than it uses. Wales generated 22 TWh against 13 TWh consumed, which makes it a net exporter, from 4.8 GW of renewable capacity, and in 2024 renewable generation was equal to 55% of Welsh electricity consumption. Just over 1.4 GW of that was solar PV at the end of 2024, with 151 MW added during the year. Storage on the ground is a fraction of what is consented: 115 MW of battery storage was operating, against more than 2.3 GW that had planning permission. The targets are renewables equal to 70% of consumption by 2030 and 100% by 2035. For a business this is context rather than a payment: what a battery can earn from flexibility depends on what the network operator buys at your connection. Where a site's own import capacity is the problem, our guide to how a battery works round a constrained connection sets out what storage can and cannot do.

Cardiff and the M4 corridor

The M4 runs from Newport through Cardiff and Bridgend to Swansea, and every business site along it connects to the South Wales network described above. For the capital's industrial estates, postcode districts and local grid detail, see our page for Cardiff and South Glamorgan sites; the figures on this page apply to the whole of the south, whichever town the meter is in.

What a Welsh business should do first

1. Get twelve months of half-hourly data from your supplier or meter operator. Monthly totals cannot show a 17:00 to 19:30 peak.
2. Count the weekdays your site really draws heavily between 17:00 and 19:30, and note the size of the peak on those days.
3. Run the calculator on the South Wales rates, or on the SP Manweb figures from your own DUoS statement if you are in the north.
4. Ask your network operator whether a lower agreed capacity is possible once the peak is managed, since unused kVA costs 10.49p a day in the south.
5. Read the tax position, then compare quotes in writing with our quote comparison checklist, asking each bidder which red-band hours and rates it used.

Sources for the figures on this page

• National Grid Electricity Distribution (South Wales) plc, Schedule of charges and other tables 2026/27, Annex 1 LV, HV and UMS charges (effective 1 April 2026, Final), re-read 2026-11-03: time bands, unit rates, capacity and exceeded-capacity charges. East Midlands comparison from the East Midlands schedule.
• National Grid Electricity Distribution, South Wales Long Term Development Statement (November 2024): customers, area and extent of the South Wales licence area. Ofgem, SP Energy Networks summary: SP Manweb covers Merseyside and North Wales. Both read 2026-11-03.
• NESO, streamlining connection projects under 5MW (12 May 2025): the CMP446 Transmission Impact Assessment threshold, read 2026-11-03.
• European Commission PVGIS v5.3: Cardiff (51.4816, -3.1791), Swansea (51.6214, -3.9436) and Wrexham (53.043, -2.9925), 1 kWp, 14% losses, read 2026-11-03.
• SI 2012/2318 and SI 2019/330: Part 43 permitted development for non-domestic microgeneration in Wales, read 2026-11-03.
• SI 2023/1229: the Welsh renewables plant exception from rating valuation, read 2026-11-03.
• Development Bank of Wales, Green Business Loan Scheme; Senedd written question WQ96151 (loan size and term); Welsh Government, extra £10 million for the scheme. Read 2026-11-03.
• Welsh Government, Ynni Cymru capital grant 2026 to 2027, its guidance and awards list, read 2026-11-03.
• Welsh Government, Future Proofing Fund (2024-25) and Salix, Wales Funding Programme, read 2026-11-03.
• Welsh Government, Energy Generation and Use in Wales, first combined edition (August 2026): generation, consumption, solar and battery storage capacity and targets, read 2026-11-03.
• Ofgem, Smart Export Guarantee: applies to installations in Great Britain, read 2026-11-03.