UK electricity generation looks, at a glance, like one industry. It is really two. About 1,300 UK generating companies publish full accounts, booking £83.5bn of combined turnover between them — but that figure spans two completely different kinds of business, and you cannot read one with the other’s yardstick.
At the top are a dozen vertically-integrated giants — Centrica, EDF, Drax, RWE, SSE, ScottishPower — that generate at scale and (in some cases) also retail power. Below them sits a swarm of single-asset special-purpose vehicles: one wind farm, one solar park, one biomass plant, each incorporated as its own company. That structure is the single most important thing to understand before reading any number here. Figures are approximate — verify against a company’s own accounts before relying on any single number.
The caveat that changes every margin
A wind-farm SPV books its power-purchase revenue, carries almost no employees, and parks its costs in depreciation and finance charges. The result is a reported margin of 40–90% that says nothing about operating quality — it is the signature of an asset-financing structure, not a well-run trading business. Several of the highest-margin companies below have one employee. Read their margins as “this asset is throwing off contracted cashflow”, not “this is a great company.”
Two further distortions: the £83.5bn double-counts, because the integrated suppliers book retail as well as generation revenue (Centrica’s £24.6bn is mostly British Gas, not turbines); and the company count is inflated by the one-asset-one-company convention, so “company count” is closer to “project count” than “competitor count.”
The shape of the market
Profitability climbs steeply with size — every one of the ten £1bn+ filers is profitable — but that is the SPV effect again: the large, contracted renewable and nuclear assets are reliably cash-generative, while the sub-£1M tier (29% profitable) is dominated by tiny or pre-revenue projects.
The giants — revenue falling as the crisis unwinds
The integrated generators all show sharp turnover declines in the latest year — Centrica −26%, EDF −24%, Drax −22%, Uniper −43%, RWE Generation −43%, VPI −53/−57% — consistent with wholesale power prices normalising after the 2022 energy-crisis spike rather than with falling output. Profits held up better than revenue, and the nuclear and renewables arms grew: EDF Nuclear Generation +19% (£2.11bn PBT), SSE Generation +42%, ScottishPower Renewables +37% (£703M PBT).
| Company | Turnover | PBT | Turnover YoY |
|---|---|---|---|
| Centrica | £24.64bn | £1.68bn | −26% |
| EDF Energy | £10.61bn | £562.0M | −24% |
| Drax Power | £4.96bn | £785.6M | −22% |
| EDF Energy Nuclear Generation | £4.04bn | £2.11bn | +19% |
| Uniper UK | £3.51bn | £10.0M | −43% |
| RWE Generation UK | £1.59bn | £401.0M | −43% |
| RWE Renewables UK Swindon | £1.29bn | £456.8M | +18% |
| SSE Generation | £941.3M | £54.3M | +42% |
| ScottishPower Renewables (UK) | £881.9M | £702.9M | +37% |
Where the “margins” are: contracted renewable assets
The best-run-by-margin table is, almost entirely, a list of wind, hydro, solar and energy-from-waste SPVs running 40–90% margins on a handful of staff. This is the asset-backed renewable cashflow machine — and a reminder that these are projects, not operating companies.
| Company | Turnover | PBT | Margin | Headcount |
|---|---|---|---|---|
| Onpath Energy | £95.7M | £56.9M | 59.5% | 67 |
| Pen Y Cymoedd Wind Farm | £91.9M | £44.3M | 48.2% | — |
| E.ON UK Steven’s Croft (biomass) | £87.6M | £44.1M | 50.4% | 30 |
| RWE Renewables UK Onshore Wind | £83.6M | £44.0M | 52.7% | — |
| SWM UK Wind One | £69.9M | £63.2M | 90.4% | 1 |
| Marchwood Power | £63.1M | £39.8M | 63.0% | 51 |
| Drax River Hydro | £63.0M | £45.3M | 71.9% | 35 |
| Fallago Rig Windfarm | £60.1M | £42.1M | 70.1% | — |
A 90% margin on one employee (SWM UK Wind One) is the SPV structure in its purest form: revenue is a contracted price for power, the turbine is depreciated, and there is no operating organisation to speak of.
Growth, read with care
This is the noisiest growth table in any report we have run, because new renewable projects ramp from near-zero: a solar farm’s first full year of generation shows +5,000% to +50,000% turnover growth, and many are loss-making while depreciation outruns early revenue. The honest signal is buried — EP NI Energy (+7,804% to £149M, profitable) and Doggerbank Offshore Wind Project 1 (+2,860%, 29% margin) are genuine large-asset commissionings; the rest is the renewables build-out arriving on the register one SPV at a time.
Market structure and vintage
Concentration looks high (top 5 = 57% of turnover) but that figure is the integrated suppliers; the generation asset base below them is highly fragmented across hundreds of project companies. The vintage profile is the giveaway: the largest cohort is 2010–15 (497 firms), with 2016–20 (297) and 2021+ (204) close behind — the renewables build-out, each project incorporated as it reached financial close. There is almost nothing pre-1990 (19 firms): this is a young, policy-built asset base.
What the map shows
- Two industries, one label. A dozen integrated giants and a thousand single-asset SPVs share it. Never read one with the other’s yardstick.
- SPV margins are a financing artifact. 40–90% on one employee means contracted cashflow off a depreciated asset, not operating quality.
- The giants are post-crisis, not in decline. Revenue fell a quarter as wholesale prices normalised; the nuclear and renewables arms actually grew.
- The asset base is young and policy-built. The dominant vintage is 2010 onward — the renewables build-out, arriving one project company at a time.
Methodology and caveats
This covers only the UK generating companies that publish full accounts (a large share file abridged or dormant accounts with no figures). The company count overstates competitor count because of the one-asset-one-company convention; combined turnover double-counts integrated suppliers’ retail revenue; extreme proportional outliers are excluded from the charts. Figures are approximate and ownership/causation notes are directional. This is analysis, not financial advice — verify any specific figure against the company’s own accounts.