The Department for Energy Security and Net Zero publishes solar installation costs for every UK region, drawn from the MCS Installation Database. It publishes them twice, on two different capacity measures, and the two versions do not agree about which region is most expensive.
This report sets out both, shows where the ranking moves, and identifies a pattern in the gap between the two measures that DESNZ’s own guidance does not describe.
Key findings
- On the declared net capacity basis, the South West is the most expensive region in Great Britain at £2,043 per kW. On the total installed capacity basis it falls to fourth, and London becomes the most expensive at £1,899 per kW.
- Five of the eleven regions move two places or more between the two rankings. The South West and the West Midlands each fall three places; the North East and the East of England each rise two, and Scotland falls two.
- The gap between the two measures ranges from 5.4% in London to 14.9% in the South West. DESNZ states the gap is typically 6% to 12%. Three regions sit outside that range.
- The proportion of installations that change size band between the two datasets varies from 7.5% in the North East to 26.7% in Wales, where more than a quarter of systems classed as small on one basis are not small on the other.
- Wales is the cheapest region on the total installed capacity basis and the second cheapest on declared net capacity. The North East is cheapest on declared net capacity and ninth on the other.
Why there are two figures
DESNZ measures a solar installation’s capacity two ways. Declared net capacity is the maximum an installation could export to the grid at one time, which is limited by the inverter. Total installed capacity is the total the panels could generate, which is usually higher because arrays are commonly oversized relative to the inverter.
Divide the same installed cost by a larger capacity figure and the cost per kW falls. That is the entire reason the two datasets differ, and it is why a cost per kW figure means little unless you know which measure produced it. We set out the consequences for household prices on our solar cost page.
Regional costs, declared net capacity basis
All installation types, 2025/26.
| Rank | Region | Mean £/kW | Installations |
|---|---|---|---|
| 1 | South West | £2,043 | 30,988 |
| 2 | London | £2,007 | 8,045 |
| 3 | South East | £1,971 | 36,907 |
| 4 | East Midlands | £1,965 | 24,703 |
| 5 | West Midlands | £1,940 | 22,024 |
| 6 | North West | £1,934 | 22,981 |
| 7 | Yorkshire and The Humber | £1,892 | 18,822 |
| 8 | Scotland | £1,877 | 28,369 |
| 9 | East of England | £1,872 | 28,965 |
| 10 | Wales | £1,867 | 22,532 |
| 11 | North East | £1,819 | 13,288 |
DESNZ Solar PV cost data 2025/26, declared net capacity basis. Ranked most to least expensive. The spread from top to bottom is 12.3%.
Regional costs, total installed capacity basis
The same installations, the same year, measured the other way.
| Rank | Region | Mean £/kW | Installations |
|---|---|---|---|
| 1 | London | £1,899 | 7,998 |
| 2 | South East | £1,766 | 36,678 |
| 3 | East Midlands | £1,744 | 24,687 |
| 4 | South West | £1,739 | 30,971 |
| 5 | North West | £1,714 | 22,983 |
| 6 | Yorkshire and The Humber | £1,709 | 18,824 |
| 7 | East of England | £1,708 | 28,708 |
| 8 | West Midlands | £1,700 | 21,961 |
| 9 | North East | £1,696 | 13,283 |
| 10 | Scotland | £1,692 | 28,224 |
| 11 | Wales | £1,646 | 22,460 |
DESNZ Solar PV cost data 2025/26, total installed capacity basis. The spread from top to bottom is 15.4%, wider than on the other basis despite every figure being lower.
Where the ranking moves
Setting the two side by side shows how much of a regional cost claim depends on an unstated methodological choice.
| Region | Rank, DNC | Rank, TIC | Movement |
|---|---|---|---|
| London | 2 | 1 | Up 1 |
| South East | 3 | 2 | Up 1 |
| East Midlands | 4 | 3 | Up 1 |
| South West | 1 | 4 | Down 3 |
| North West | 6 | 5 | Up 1 |
| Yorkshire and The Humber | 7 | 6 | Up 1 |
| East of England | 9 | 7 | Up 2 |
| West Midlands | 5 | 8 | Down 3 |
| North East | 11 | 9 | Up 2 |
| Scotland | 8 | 10 | Down 2 |
| Wales | 10 | 11 | Down 1 |
Our calculation from the two DESNZ datasets. Rank 1 is the most expensive.
The headline result is the South West. On one official measure it is the most expensive place in Great Britain to install solar, above London. On the other, three regions cost more. Both figures come from the same department, the same release and the same installations.
Every region got cheaper
Whatever the ranking, costs fell in all eleven regions between 2024/25 and 2025/26, on both measures. The size of the fall varied widely.
| Region | Change, DNC basis | Change, TIC basis |
|---|---|---|
| Wales | -7.7% | -6.4% |
| London | -6.4% | -3.2% |
| West Midlands | -6.0% | -6.4% |
| East Midlands | -4.8% | -4.3% |
| South East | -4.7% | -2.9% |
| South West | -4.6% | -3.8% |
| North West | -4.0% | -4.7% |
| North East | -3.9% | -3.4% |
| East of England | -3.6% | -2.8% |
| Yorkshire and The Humber | -2.4% | -2.0% |
| Scotland | -2.0% | -1.8% |
Our calculation from the 2024/25 and 2025/26 regional means in the same DESNZ release. Ordered by the fall on the declared net capacity basis.
Wales saw the largest fall on one measure and was joint largest, with the West Midlands, on the other. Scotland saw the smallest fall on both, less than a third of the Welsh reduction, despite already being among the cheaper regions.
The finding DESNZ does not describe
DESNZ’s guidance states that total installed capacity figures are typically 6% to 12% lower than declared net capacity figures. That holds nationally. It does not hold evenly across regions.
| Region | Gap between the two measures |
|---|---|
| South West | 14.9% |
| West Midlands | 12.4% |
| Wales | 11.9% |
| North West | 11.4% |
| East Midlands | 11.3% |
| South East | 10.4% |
| Scotland | 9.8% |
| Yorkshire and The Humber | 9.7% |
| East of England | 8.7% |
| North East | 6.8% |
| London | 5.4% |
Our calculation from the two DESNZ datasets, expressed as the reduction from the declared net capacity mean to the total installed capacity mean.
The gap is nearly three times larger in the South West than in London, and four regions fall outside the 6% to 12% range DESNZ describes.
Because the gap reflects how far panel capacity exceeds inverter capacity, a wider gap implies arrays that are more heavily oversized relative to their inverters. On that reading, installations in the South West and West Midlands are being specified differently from those in London and the North East. We cannot confirm that from this dataset alone, and we are not going to assert a cause we have not tested. But the variation is real, it is large, and it is not described in the accompanying guidance.
How many installations change size band
Because each dataset sorts installations into size bands using its own capacity measure, the same house can appear in different bands in the two files. Nationally this moves around 25,000 domestic installations out of the 0 to 4 kW band. Regionally the effect is very uneven.
| Region | Share of the 0-4 kW band that moves up |
|---|---|
| Wales | 26.7% |
| South West | 22.4% |
| Scotland | 17.4% |
| West Midlands | 16.7% |
| South East | 14.6% |
| North West | 14.3% |
| Yorkshire and The Humber | 13.4% |
| East Midlands | 12.6% |
| London | 12.0% |
| East of England | 11.2% |
| North East | 7.5% |
Our calculation, comparing the count of installations in the 0 to 4 kW band in each dataset.
In Wales, more than a quarter of the installations counted as small systems on one basis are not small systems on the other. Any statement of the form “the average cost of a small solar system in Wales” is therefore resting on a choice of measure that changes which installations are being averaged.
What this means if you are quoting a regional figure
Three practical conclusions.
State which basis you are using. A regional cost per kW without a stated measure is not a checkable figure. We use declared net capacity as our headline because it is directly comparable with previous years, and give the other alongside.
Treat regional rankings carefully, including ours. The spread between the most and least expensive region is 12% to 15% depending on basis. The gap between the two measures within a single region reaches 14.9%. The methodological difference is larger than most of the regional differences it is being used to describe.
Do not read a regional average as a household price. These figures cover all installation types, including commercial installations, which are cheaper per kW and unevenly distributed. For household prices by system size, see our solar cost page, which uses the domestic-only figures.
Method and limitations
All figures are taken directly from the two spreadsheets published by DESNZ alongside its Solar PV cost data release of 28 May 2026, covering financial year 2025/26. Rankings, gaps and band-shift percentages are our own calculations from those figures, and the underlying means are published by DESNZ unaltered.
Three limitations worth stating. The regional tables cover all installation types rather than domestic only, so they are not directly comparable with the domestic figures we use elsewhere. London’s coverage is the lowest of any region, at 92% to 93% depending on the basis, against 96% to 99% everywhere else, so its figures rest on a smaller share of installations. And the total installed capacity series is classed by DESNZ as Official Statistics in development, which means its methodology may change.
Northern Ireland is not included in the dataset, which covers England, Scotland and Wales only.
Sources
- DESNZ, Solar PV cost data, 2025/26 release, published 28 May 2026 (DNC basis spreadsheet, Regional costs table)
- DESNZ, Solar PV cost data, 2025/26 release, published 28 May 2026 (TIC basis spreadsheet, Regional costs table)
- MCS Installation Database, via the above
Last updated 28 September 2026. All cost figures are published by DESNZ in its Solar PV cost data release of 28 May 2026 and are reproduced unaltered. Rankings, the gap between capacity measures, the band-shift percentages, the spread figures and the year-on-year changes are our own calculations from those published means. Regional tables cover all installation types across England, Scotland and Wales; Northern Ireland is not included. The total installed capacity series is classed by DESNZ as Official Statistics in development. Written by Ben Jardine.