Industrial & Logistics Property: Solar for Commercial Property

A big-box distribution shed has the best solar roof in commercial property — and the most awkward ownership question. The roof is vast, flat, structurally simple and almost always let on a full-repairing-and-insuring (FRI) lease to a single, often strong-covenant occupier. As the owner you control the asset; the tenant controls the meter and pays the energy bill. That is the split incentive in its purest form: spend the capital and the savings land on someone else’s profit-and-loss. The way through is to stop asking “should I install solar” and start asking “which party funds it, which party consumes it, and how does the lease share the value”. For most single-let logistics assets the answer is a roof lease or airspace lease — you sell the roof to a developer who funds and owns the array, you take an index-linked rent plus a discounted-power offer to your tenant, and you carry zero capex. We model all five routes for you in our split-incentive guide, but on this asset class the roof-lease route usually wins.

Why big-box logistics has the best cost-per-kWp in commercial property

Cost per kilowatt-peak (kWp) falls hard with scale, and nothing scales like a distribution shed. A 50 kWp install on a small unit lands around £1,000–£1,100/kWp; a 500 kWp-plus array on a logistics roof comes in at roughly £700–£850/kWp ex VAT (commercial solar has been 0% VAT since April 2022). The fixed costs — design, G99 application, scaffolding mobilisation, inverter housing, professional fees — spread across far more panels, so each additional kilowatt is cheaper than the last.

The roof itself helps. These are large, unbroken, low-pitch or flat membranes with minimal shading, few roof penetrations and clear access — the cheapest possible surface to mount on. Generation scales with the same logic: at a UK yield of roughly 950 kWh/kWp/year, a 250 kW array produces around 237,000 kWh annually and a 1 MW array around 950,000 kWh. That is a serious energy asset sitting on a roof that would otherwise generate nothing.

There is a real prize in the self-consumption profile too. Distribution and manufacturing sites with daytime shift patterns, refrigeration, automation or battery-electric MHV fleets consume a high share of generation on site, where every kilowatt-hour displaces grid power at roughly 24–28p/kWh rather than being exported for a SEG top-up of around 12–16p. Self-consumption is the single biggest return driver, and logistics operations are among the best-matched loads in the commercial estate.

Strong-covenant single-let sheds are prime “sell the roof” candidates

A single-let logistics asset on a long lease to a national 3PL, retailer or manufacturer is the textbook airspace-lease deal. Here is the structure:

• A developer or funder leases your roof (an airspace lease — a registrable interest at Land Registry, typically 20–30 years), funds 100% of the install and owns the array.
• You receive an index-linked roof rent for the life of the lease.
• Your tenant is offered power at a discount to grid under a behind-the-meter power purchase agreement (PPA), improving their occupancy cost — a genuine retention and re-letting tool.
• You commit no capital, take no technology risk and hold no maintenance liability.

The trade-off is honest: you don’t capture the full energy economics — the developer does, in exchange for funding everything — and “no sun, no power” means generation is weather-dependent, so the PPA is a top-up to grid, not a replacement. An airspace lease is also a property transaction with consequences: it needs mortgagee (lender) and insurer consent, has potential SDLT and Land Registry registration implications, and interacts with your reversion and any future sale. We walk through the comparison — roof lease versus landlord PPA versus licence — in roof lease vs PPA vs licence, and the structures specific to let stock in let investment property.

If you’d rather own the economics outright — common where you intend to hold long-term or where the covenant or lease length doesn’t suit a funder — a landlord-funded PPA to the tenant, or simply owning the array and selling power, keeps 100% of the upside with you. That route relies on the Annual Investment Allowance (AIA) for the 100% first-year tax relief; note that assets bought specifically to lease don’t qualify for the 50% First-Year Allowance, so the funding-versus-tax interaction matters and we model it case by case.

Roof lifecycle, structural survey and EPC: the diligence that protects the deal

Three pieces of diligence make or break an industrial solar project. We front-load all of them.

Re-roof and solar in one project. Solar wants 20–30 years of life on the roof beneath it; retrofitting an array onto a membrane with under 15 years left is a false economy because you’ll be lifting panels to re-roof mid-life. If your roof is approaching renewal, the efficient move is to combine re-roof and solar into a single project — one scaffold, one access programme, one disruption window — and align the warranties. We flag this on every survey.

Structural roof-loading survey to BS EN 1991. Older sheds, and many speculative big-box roofs, were built to the minimum loading standard of their day. Panels, ballast and fixings add dead load and alter wind uplift behaviour. A structural survey to BS EN 1991 (the Eurocode loading standard) is a precondition, not an optional check — it determines mounting system, ballast strategy and whether any strengthening is needed. Skipping it is the fastest way to a failed install.

EPC uplift protects lettability. Minimum Energy Efficiency Standards (MEES) already make it unlawful to let commercial property in England and Wales below EPC E (since 1 April 2023, even to sitting tenants). Beyond the legal floor, the Government’s interim response of 18 June 2026 proposes EPC B by 2031 for privately-rented non-domestic buildings over 1,000 m², where cost-effective and subject to secondary legislation — note this is a proposal, not yet law, and the earlier “EPC C by 2027” target was scrapped. Most logistics sheds comfortably exceed 1,000 m², so this proposal squarely targets the asset class. Solar typically lifts a commercial EPC by one to three bands (we never promise a specific jump). For the institutional funds and REITs that dominate logistics ownership, a defensible EPC is what keeps a building lettable and financeable — and that is precisely what protects value here, more than the energy saving alone. See the MEES and EPC guide for the detail and dates.

Planning is open; the grid connection is the real constraint

The old 1 MW cap on commercial rooftop solar was removed on 21 December 2023 (SI 2023/1279), so megawatt-scale arrays on a single shed are now firmly in scope. Rooftop commercial solar is permitted development under Class J, but it carries a 56-day prior-approval step covering design, appearance and glint/glare — not a free pass, and listed buildings, scheduled monuments and sites under an Article 4 Direction are excluded. Class OA separately permits car-park solar canopies, which large logistics sites with extensive HGV and staff parking can use as an additional generation and EV-amenity layer.

The genuine bottleneck is the G99 DNO grid connection. Any array above roughly 50 kW needs a connection agreement from the Distribution Network Operator, and on constrained parts of the network the offer, the timeline and the cost — including any reinforcement contribution — now drive the whole programme. We treat the G99 application as the critical path from day one. Full detail on permitted development, prior approval and the connection process is in planning and grid for commercial solar.

Worked example (illustrative only)

A 9,000 m² single-let distribution warehouse, let on a 15-year FRI lease to a national 3PL operator. The roof carries a 500 kWp array.

• Generation: ~475,000 kWh/year at 950 kWh/kWp.
• Indicative capital cost: ~£400,000 ex VAT (at ~£800/kWp) — borne by the funder under an airspace lease, so £0 to the owner.
• Owner outcome (roof-lease route): an index-linked roof rent for the 20–25 year lease term, an EPC uplift that strengthens lettability at the next rent review or re-letting, and no capex, maintenance or technology risk.
• Tenant outcome: a behind-the-meter PPA priced below grid, cutting occupancy cost on a daytime-heavy load — a real retention lever.

These figures are illustrative, not a quote. Actual numbers depend on the structural survey, the DNO connection offer, the tenant’s load profile, the covenant strength and the lease terms. We model your specific asset, including the owner-transaction layer — lender and insurer consent, dilapidations, reversion and rent-review interaction — in the owner’s due-diligence guide.

Common questions

Will solar interfere with selling or refinancing the building?

It can, if it’s not structured correctly — which is exactly why the property-transaction layer matters. An airspace lease is a registrable interest, so it sits on the title and a buyer’s or lender’s solicitor will scrutinise it; you need mortgagee and insurer consent in place before signing, and a clean s.198 fixtures election if there’s a sale. Done properly, a defensible EPC and a long-dated rental income stream are positives at refinance, not drags. We pressure-test the lender and reversion impact before you commit, in owners’ due diligence.

My tenant pays the energy bills under an FRI lease — why would I bother with solar?

Because the value to you isn’t only the energy. Under a roof lease you take a rent for an asset that currently generates nothing, and the EPC uplift protects the lettability and capital value of a building that institutional buyers won’t touch below a defensible energy rating. The tenant benefit — cheaper power — becomes your retention and re-letting tool. You solve the split incentive by letting the funder carry the capital and the tenant take the discount, while you keep the rent and the asset upgrade.

How big an array can a logistics roof actually take now?

Since the 1 MW planning cap was removed in December 2023, the limiting factors are physical roof area, the BS EN 1991 structural loading assessment and — most often — the G99 grid connection the DNO will offer. A typical big-box roof supports anywhere from 250 kW to well over 1 MW. We size to the binding constraint: there’s no point designing a 1 MW array if the local network will only accept 600 kW without expensive reinforcement, so we run the structural and DNO checks early. Request a quote and we’ll scope your specific roof.