PSDS vs Great British Energy Solar: Which Funds NHS Solar?

For a Trust estates team plotting a rooftop programme, NHS solar funding no longer means one scheme. Two national routes now sit on the table: the long-established Public Sector Decarbonisation Scheme (PSDS), run by Salix Finance on behalf of DESNZ, and the newer Great British Energy programme, which has been set up to fund solar on around 200 NHS sites. They are not competitors so much as complementary instruments with different shapes, and knowing which one your scheme fits — or how to line up for both — is the difference between a project that gets funded this cycle and one that waits a year. This comparison sets out how the two routes differ, at a public-fact level, and where each tends to win.

NHS solar funding now runs on two routes

Both mechanisms exist to serve the same commitment: the NHS in England has pledged net zero by 2040, with an interim 80% reduction by 2032. Every Trust must publish a Green Plan, and on-site solar is now a standard line in almost all of them. What differs is how the money reaches the roof. PSDS is a competitive capital-grant scheme with a dedicated NHS allocation; the Great British Energy solar programme is a targeted, publicly-backed initiative to put panels specifically on NHS estate. One is a pot you apply into; the other is a rollout you may be selected for. Understanding that distinction is the starting point for any Trust deciding where to put its energy.

How PSDS works — the competitive capital grant

PSDS is the route most estates teams already know. It is run by Salix Finance for DESNZ, and its Phase 4 window carries a dedicated NHS allocation. All NHS Trusts, foundation trusts, and NHS-owned facilities are eligible, and eligible measures — low-carbon heating, building fabric, and on-site renewables — can be funded at up to 100% of capital cost. Trust-scale applications typically run from £500,000 into the low millions and above.

Its defining characteristics are that it is competitive and evidence-heavy. The scheme is heavily oversubscribed, so strong applications win and weak or late ones do not. The energy savings calculation must be auditable — in practice, SBEM modelling of the building baseline and PVSyst yield modelling for the solar contribution, backed by twelve months of half-hourly consumption data. The typical application-to-grant timeline runs to four to six months. Crucially for hospitals, PSDS exists primarily to decarbonise heat, so applications that pair heat pump electrification with rooftop PV score particularly well — the PV supplies the new electrical load the heat pumps create. Combined heat pump plus PV schemes routinely sit in the £2–10m range per Trust site and are frequently 80–100% grant funded. Our PSDS funding guide sets out the full mechanics, and the NHS Trust solar page covers how the governance stacks up.

How the Great British Energy programme works — targeted rollout

The Great British Energy programme is the newer arrival. It is a publicly-owned energy initiative, and as part of its early work it has been established to fund solar panels on around 200 NHS sites. The character of this route is different from PSDS in an important way: rather than every Trust assembling a competitive evidence pack and bidding into a shared pot, it is a targeted programme that puts panels on a defined set of NHS estate, backed by public capital rather than a Trust-led grant application.

Because this is a rollout aimed at specific sites, the practical question for an estates team is less "how do I write the strongest application?" and more "is my site in scope, and how do I make sure my roofs are install-ready if selected?" A Trust that keeps its half-hourly data current, its roof surveys fresh, and its Green Plan solar ambitions clearly documented is in the best position to benefit from a targeted programme — the same groundwork that strengthens a PSDS bid also makes a site an easy, deliverable candidate for a rollout. We have deliberately kept this section qualitative: beyond the publicly stated aim of funding solar across around 200 NHS sites, specific per-site envelopes are not something a responsible Trust should plan around until confirmed for its own estate.

It is worth being clear-eyed about what a publicly-funded rollout still demands on the ground. Whichever route pays for the panels, a hospital install is a hospital install: it must respect HTM 06-01 electrical services standards, follow HTM 03-01 infection control protocols during construction, and be signed off by an Authorising Engineer (Electrical). Any system above 17 kW per phase needs a G99 application to the DNO, though hospital sites are often less constrained here because they typically carry large existing connections with spare capacity. A funding source changes who pays; it does not change the compliance and delivery bar, and the sites that move fastest under either route are the ones whose estates teams have already worked those requirements into their feasibility.

Side by side: where each route fits

The clearest way to think about the two is by the shape of the decision. PSDS rewards Trusts that can prepare, evidence, and submit — it is application-led, competitive, and best-in-class for combined heat-and-power schemes at scale. The Great British Energy programme rewards Trusts whose sites are ready and in scope for a national rollout — it is selection-led rather than bid-led. The two are not mutually exclusive; a Trust can hold PSDS ambitions for its larger combined heat pump and PV schemes while remaining an install-ready candidate for a targeted solar programme on other roofs.

• Scheme type: PSDS is a competitive capital grant you apply into; the Great British Energy route is a targeted, publicly-backed solar rollout you may be selected for.
• Delivered by: PSDS via Salix Finance for DESNZ, with a dedicated NHS allocation; the Great British Energy programme via the publicly-owned company set up to fund solar on around 200 NHS sites.
• Best fit: PSDS suits large, combined heat pump plus PV business cases (£2–10m range) where an evidence pack and heat decarbonisation story exist; the rollout route suits solar-ready NHS roofs on in-scope sites.
• What it demands of you: PSDS demands an auditable evidence pack and a submission in the window; the rollout route demands install-readiness — current data, fresh roof surveys, documented Green Plan intent.

How to position your Trust for both

The good news is that the preparation is largely the same, so no Trust needs to bet on one route. The groundwork that wins a PSDS grant — twelve months of half-hourly data covering both winter heating and summer cooling peaks, roof drawings, system sizing, a costed feasibility, and Green Plan alignment — is exactly the groundwork that makes a site a clean, deliverable candidate for a targeted rollout. Do the feasibility once and it serves both routes.

Alongside these national schemes, remember the fallback ladder still exists: the interest-free Salix Decarbonisation Loan suits projects in the £100k–£1m band, and Trust operational capital can carry smaller schemes or fund a Trust contribution to a co-funded programme. None of these are as generous as a grant or a publicly-funded rollout at up to 100% of capital, but they keep a programme moving between windows. Note too that most NHS bodies are not corporation-tax payers, so tax-side reliefs like the Annual Investment Allowance rarely help a Trust directly — the value here sits in capital grants and public funding, not tax shielding.

The practical conclusion for NHS solar funding is that the winning strategy is not to choose PSDS versus Great British Energy in the abstract, but to get your estate ready and then let the strongest available route fund it. A costed feasibility and an auditable evidence pack put a Trust in pole position for a competitive PSDS grant and simultaneously make its roofs an obvious candidate for a targeted solar rollout. Our PSDS funding page walks through the grant route in detail, the NHS Trust solar page covers governance and delivery, and a free desk feasibility from your half-hourly data is the single artefact that unlocks both routes at once — the practical starting point for NHS solar funding, whichever route ends up paying for the panels.