Commercial Property Portfolios: Solar for Commercial Property

A portfolio is not a building with more roofs. It is a different problem. A single asset is an engineering decision; an estate of 20, 80 or 300 assets is a capital-allocation, disclosure and governance decision in which the solar engineering is the easy part. The hard part is doing the same thing 80 times, consistently, while every asset sits at a different point in its lease cycle, its roof lifecycle, its EPC band and its CRREM stranding pathway. Most installers can quote one roof. Almost none can run a programme. That gap is what this page is about.

The portfolio owner’s specific problem

For a fund, a REIT or a multi-asset landlord, solar has to clear three hurdles a single-site owner never sees. First, heterogeneity: a logistics shed, a multi-let office and a retail park each have a different occupier mix, a different supply-point structure and a different route through the split incentive — there is no single template. Second, governance and reporting: capital committees, fund mandates and investor disclosure all need to see a consistent business case, asset by asset, in a form that ties back to GRESB scoring and CRREM pathways. Third, the tail risk of doing it badly at scale — a fixtures-election error or a roof-lease consent failure replicated across 80 assets is not 80 small problems, it is one large one.

We solve this by treating the estate as a programme, not a series of projects. One standardised method, applied to every asset, producing one comparable output per building, prioritised by where capital does the most work. The deliverable is not a quote; it is a rollout schedule the capital committee can actually approve.

The standardised survey-to-switch-on programme

Every asset passes through the same five gates, so the output is comparable across the whole estate:

1. Triage and prioritisation. We score each asset on EPC band, lease structure (single-let, multi-let, FRI, vacant), roof age and condition, supply-point control, and CRREM stranding date. Assets near a stranding inflection, near a lease event, or with landlord-controlled common-parts supply rise to the top — that is where solar moves the most value soonest.
2. Standardised technical survey. Structural roof-loading check to BS EN 1991, roof membrane life assessment, DNO capacity pre-check (the G99 connection above ~50kW is now the real delivery bottleneck, not planning), and a self-consumption model per supply point.
3. Ownership and lease structuring. The right route per asset — common-parts landlord supply, landlord-to-tenant PPA, roof/airspace lease, green-lease contribution or owner-occupier. See the split incentive solved and roof lease vs PPA vs licence.
4. Funding and approvals pack. A per-asset business case in one consistent format, plus the consent register (mortgagee, insurer, superior landlord) the deal needs.
5. Build, commission, monitor. Standardised installation specification, then live generation and consumption data feeding straight into your Scope 2 and GRESB reporting.

The full method is set out in our commercial property portfolio rollout guide.

Sizing and economics across an estate

A portfolio programme typically deploys 500 kW to 5 MW+ of capacity across the estate — anywhere from £350,000 on a focused first phase to £3,000,000+ for a full multi-asset rollout. At a UK yield of roughly 950 kWh/kWp/year, that generates 460,000 to 4,600,000+ kWh annually. Commercial installation has carried 0% VAT since April 2022, and at scale capex trends toward the lower end of the £700–£1,100/kWp range.

The economics are driven by self-consumption, not export. Self-consumed solar displaces grid electricity at roughly 24–28p/kWh (2026 commercial rates, ex VAT/CCL); surplus exported under the Smart Export Guarantee earns a supplier-set rate of around 12–16p — a top-up, not the headline. Where a supply point self-consumes 60–80% of generation (single daytime shift, or with battery), payback typically lands in the 6-year region, faster on high-load assets, with AIA and the business-rates exemption shaving time off the post-tax figure. A portfolio gives you something a single asset cannot: a blended phasing strategy — fund the high-self-consumption, near-stranding assets first from the strongest returns, then roll the savings forward.

Framework funding: blended capex, asset finance, third-party roof leases

Few funds want to spend £3m of equity in one line. A portfolio programme is normally funded as a blend: direct capex where the return and the strategic case are strongest (typically owner-occupied or landlord-controlled assets); asset finance to spread cost and preserve facility headroom; and third-party roof leases where a developer funds and owns the array and you take rent plus a tenant discount with no capital outlay. The mix is set asset by asset, not estate-wide. The funding routes, and their very different tax treatment, are covered in capital allowances and funding for owners.

Compliance, disclosure and the capital that gates on it

For an institutional owner, solar is increasingly underwritten less by its payback and more by what it unlocks in compliance and disclosure.

MEES and EPC. It has been unlawful to let commercial property in England and Wales below EPC E since 1 April 2023 — that is the binding law today, the floor, and it applies even to sitting tenants. Penalties run to 10% of rateable value (capped £50,000) under three months and 20% (capped £150,000) at three months or more, plus a public breach register. Beyond that floor, EPC B by 2031 is a proposal (Government interim response, 18 June 2026) for privately-rented non-domestic buildings over 1,000 m², only where cost-effective and subject to secondary legislation — it is not law, and the earlier “EPC C by 2027” and “EPC B by 2030” lines were scrapped or never existed. We model your estate against the law that exists and flag the proposal as a proposal. Across a portfolio the exposure is real: the BPF found (October 2025) that around 83% of commercial buildings across seven major UK cities sit below EPC B. Solar typically lifts a commercial EPC by 1–3 bands — we never promise a specific jump. See MEES and EPC for commercial property.

GRESB, CRREM and Scope 2. GRESB’s 2025 cycle covered 1,002 fund managers, 2,382 assessments and over 150 institutional investors — and increasingly scores on actual measured energy and carbon intensity, not just EPC labels. CRREM 1.5°C pathways do the same at asset level, dating when each building strands on its current trajectory. On-site solar is direct Scope 2 abatement that shows up in both, and feeds SFDR Article 8/9, TCFD and SBTi Buildings disclosure — the reporting that institutional capital now gates on. Our ESG, GRESB and net-zero funds guide sets out how the generation data flows through.

The tax and fixtures layer. Solar PV is a special-rate (integral features) asset. The 100% first-year relief comes from the Annual Investment Allowance (£1m, permanent) — not from full expensing, whose 50% First-Year Allowance is unavailable on assets bought to lease. So funded, leased or roof-lease arrays rely on AIA plus the 6% writing-down allowance, not full expensing — a distinction that materially changes the after-tax model and one many generalist advisers get wrong. Critically for a portfolio that trades assets: a s.198 fixtures election is needed whenever you acquire or dispose of a let property carrying existing solar, to fix the value passing between buyer and seller. Get it wrong and the allowance can be lost entirely. We build the fixtures position into the acquisition and disposal diligence, not afterwards. Business rates add a further tailwind — rooftop solar and co-located battery storage are 100% exempt to 31 March 2035 in England.

Worked example (illustrative)

A mid-sized fund holds a 40-asset UK estate: a mix of single-let industrial, multi-let offices and three retail parks. The figures below are illustrative, to show the shape of a programme — not a quote.

• Triage. 28 of 40 assets are technically and commercially viable. 9 are near a CRREM stranding inflection or a lease event; these phase first.
• Phase 1 (year 1): 12 assets, ~1.8 MW total, ~£1.5m. Funded as a blend — £900k direct capex on owner-occupied and landlord-controlled assets, £600k asset finance.
• Phase 2 (years 2–3): 16 assets, ~2.4 MW, largely via third-party roof leases on the multi-let and retail assets (no further capital outlay; rent plus tenant discount).
• Generation, full programme: ~4.0 GWh/year, displacing grid electricity at ~26p and earning SEG ~13p on surplus.
• Compliance outcome: every let asset clears EPC E with headroom; the estate’s measured energy intensity falls, improving the GRESB submission and pushing several assets off their near-term CRREM stranding line.
• Blended payback: around 6 years on the capex-funded tranche; the leased tranche is cash-positive from day one.

The point is the programme structure — comparable assets, phased by where capital works hardest, with the compliance and disclosure benefit captured estate-wide.

Common questions

Do we have to fund the whole estate up front?

No — and almost no portfolio owner does. A programme is phased and blended: direct capex on the highest-return, most strategic assets, asset finance to spread cost, and third-party roof leases where a developer funds and owns the array so you deploy zero capital. We set the funding route asset by asset, then phase the rollout so the first wave’s returns help fund the next. The mechanics and the very different tax treatment of each route are set out in capital allowances and funding for owners.

How does solar across the estate affect our GRESB score and CRREM pathway?

It improves both, because GRESB (2025: 1,002 managers, over 150 institutional investors) and CRREM increasingly score on actual measured energy and carbon intensity, not just EPC bands. On-site solar is direct Scope 2 abatement: it lowers each asset’s measured intensity, can push assets off their near-term CRREM stranding line, and feeds SFDR Article 8/9 and TCFD disclosure. We wire the live generation data into a format your reporting team can use — see ESG, GRESB and net-zero funds.

What happens to the solar when we sell an asset in the portfolio?

It becomes a fixtures-and-allowances question, and it needs handling at the deal, not afterwards. When you dispose of a let property carrying existing solar, a s.198 fixtures election fixes the capital-allowances value passing to the buyer; get it wrong and the allowance can be lost. If the array sits under a third-party roof lease, that lease is a registrable interest the buyer inherits, with mortgagee and insurer consents to assign. We build both into acquisition and disposal diligence as standard. To scope a programme across your estate, request a portfolio assessment.