Owner's Due Diligence: Lender, Insurer, Roof & Reversion

A solar installer prices the panels. An owner has to price the consequences. The moment a commercial array touches a let or mortgaged building it stops being an energy project and becomes a property transaction — one that interacts with your loan covenants, your insurance schedule, your roof warranty, your rent reviews and, twenty years out, the reinstatement obligation at lease end. Most installer quotes are silent on every one of these. This guide walks the owner-transaction layer in the order we run it, so nothing surprises you at a valuation, a refinance or a reversion.

Why the owner’s checklist is different

The occupying business buying solar for its own factory has one question: does it pay back. The owner of a let or financed building has a longer list, because the asset is collateral, an investment and a landlord’s reversionary interest all at once. A decision that improves the energy economics can quietly breach a loan covenant, void a roof warranty, or hand a tenant an asset you then have to buy back at lease end.

None of this kills a solar project. It changes the sequence. Get the consents and surveys done before you commit capital or sign a roof lease, and the install adds value cleanly. Skip them and you discover the problem at the worst possible moment — when a valuer, a lender’s surveyor or an incoming buyer’s solicitor finds it during diligence on someone else’s timetable.

Lender and mortgagee consent

If the building is mortgaged, your facility agreement almost certainly restricts what you can do to it — and a roof lease is the kind of thing it restricts. Before any capital goes in, read the charge and the loan covenants, then talk to the lender.

The consent question turns on the ownership route (see roof lease vs PPA vs licence for the full comparison):

• Owner-occupier or landlord-owned array (routes A and E): the panels are your fixtures on your asset. Usually no third-party consent, but a material alteration clause in the facility may still require notification. Check it.
• Landlord→tenant PPA (route B): a behind-the-meter supply contract. Lighter-touch, but the PPA is a long-term contract that an incoming lender or buyer will want to see; disclose it.
• Roof or airspace lease (route C): this is the one lenders care about. You are granting a third party a registrable legal interest in the security for 20–30 years. That ranks against the charge, and almost every mortgage requires the lender’s prior written consent before you grant a lease out of the secured property.

For a roof lease, expect the lender to want: the heads of terms, the developer’s covenant strength, evidence the lease can be determined or stepped into if the developer fails, and confirmation the array does not impair the building’s value or lettability. Some lenders will require a deed of priority or a direct agreement with the solar developer.

LTV, valuation and refinancing

A roof lease changes the encumbrances on title, which means it touches loan-to-value at the next valuation and any refinance. Two effects pull in opposite directions. A well-structured array on common parts can lift the EPC, cut void holding costs and support the green premium associated with better-rated assets — all positives a valuer can recognise. But a poorly drafted 25-year roof lease with a weak counterparty, no step-in rights and an onerous reinstatement clause is a title defect that a cautious valuer or incoming buyer will price down or, occasionally, refuse to lend against. The drafting is the difference. Get the lease reviewed by property finance counsel, not just an energy lawyer, before you sign.

Insurer notification and re-rating

Tell your insurer before the install, not after. A rooftop array is a material change to the risk, and not disclosing it can prejudice a claim. Most commercial property policies require notification of alterations; solar plant is squarely within that.

What to expect:

• Re-rating of the buildings cover. Panels add value-at-risk and a new failure mode (DC arc faults, connector heat). Premiums may move; the insurer may impose conditions on installer certification, isolation and maintenance.
• A structural survey as a precondition. Many insurers will not confirm cover until a structural engineer has signed off the roof loading (see below).
• Battery storage is a separate, harder conversation. A co-located BESS introduces lithium-ion fire risk. Some insurers exclude it, others require specific separation distances, fire suppression, thermal-runaway detection and siting away from the building line. Raise BESS with the insurer at the outset — discovering an exclusion after install is expensive.

Where a third party owns the array under a roof lease, agree in the lease who insures the panels, who insures the building, and how the two policies interlock so there is no gap and no double-recovery dispute after a fire.

Structural roof-loading survey

A chartered structural engineer must confirm the roof can carry the array under BS EN 1991 (the Eurocode loading standard) before anything is fixed. This is non-negotiable and it is the survey most installer quotes assume away.

The engineer assesses the dead load of the panels and mounting, plus the wind uplift and snow loads the Eurocode requires for the building’s location and exposure. Older industrial and logistics roofs — large-span steel portal frames especially — were often designed with little spare capacity, so the answer is sometimes “yes, but only with additional purlins” or “yes, on the southern slope only.” For the structural and grid realities specific to large-roof assets, see industrial and logistics property.

The structural report also feeds the insurer, the lender and the warranty position, so commission it early — it gates several other steps.

Roof lifecycle alignment

The single most expensive mistake an owner makes is bolting a 25-year array onto a roof with 10 years of membrane left. When the roof fails, you remove the solar, recover the roof and reinstall the solar — paying twice for the labour and scaffolding and losing generation throughout.

The rule is simple. Before designing the system, get the roof’s remaining life assessed:

Combining a re-roof with the solar install in a single programme is usually cheaper per unit than doing them separately, and it lets you specify a roof covering and fixing detail designed for the array from the start. If you are coordinating this across several buildings, the portfolio rollout guide covers sequencing capital works against roof condition across an estate.

Existing roof warranty — don’t void it

Penetrating or loading a roof that is still under a manufacturer or installer warranty can void it — leaving you exposed if the roof later fails. Many single-ply and built-up felt systems carry 15–25 year warranties that are conditional on no unauthorised alterations.

Before any fixing detail is finalised:

• Identify whether the roof is in warranty and read the terms.
• Where it is, involve the roofing manufacturer’s technical team. Most will approve a compliant mounting system and may insist their approved contractor carries out the penetrations to keep the warranty intact.
• Prefer ballasted or warranty-approved mounting on flat roofs where it avoids penetrations altogether.

This coordination costs a few weeks. Voiding a six-figure roof warranty costs far more.

Rent-review interaction

Solar you fund as landlord is a landlord’s improvement — and at the next rent review you generally do not want to be paying increased rent on the value you created. Standard institutional leases disregard improvements carried out by the tenant; the position on landlord-funded improvements depends entirely on the review clause and the lease structure.

The points to settle before install:

• Whose improvement is it? If the tenant funds and owns the array (a green-lease contribution, for example), it may fall within a tenant-improvement disregard. If you fund it, it may not — and could feed the reviewed rent.
• Does the array change the rentable proposition? Common-parts solar that cuts service-charge-borne energy, or an EV-charging amenity, can support rental tone. That may be what you want — or you may want it ring-fenced. Decide deliberately.
• Green-lease drafting. Where the install sits inside a green lease, align the rent-review wording with the energy-cost-sharing mechanism so the two do not contradict. The green leases guide covers the contribution-cap mechanics.

This is a drafting question for your surveyor and solicitor, taken before the works, not a problem to discover at the review.

Dilapidations, reversion and reinstatement

The longest tail on a commercial array is what happens at the end — and a 20–30 year roof lease will routinely outlast the tenancies underneath it. Three distinct end-points need addressing up front.

Tenant dilapidations. If a tenant installs solar, the lease must say whether it reinstates at term end or whether the array stays. An owner usually wants the option to require either, depending on whether the panels still have value and life. Silence here produces a dispute.

Roof-lease reversion. Under a route-C roof lease, the developer owns the array for the lease term. At expiry, who owns it, on what terms, and in what condition does the roof come back. A well-drafted lease gives you a reversion of the array in working order at nil cost, or a clear decommissioning-and-reinstatement obligation on the developer — never an open question that hands the developer leverage.

The mismatch problem. Because the roof lease can run 25–30 years while underlying occupational tenancies turn over every 5–15, the array persists across multiple tenancies and at least one likely sale. Every occupational lease and every sale contract during that window must be drafted around the existing roof lease — disclosed, with the supply and access arrangements carried through — or you create gaps that surface as title queries on the next transaction.

SDLT and Land Registry on a roof lease

Granting a roof lease is the grant of an interest in land, with the Land Registry and SDLT consequences that follow. A lease of the roof or airspace is registrable at HM Land Registry against the freehold title and will appear on every future search.

On Stamp Duty Land Tax, the analysis turns on the consideration — typically a premium and/or rent paid by the developer to the owner. Where consideration crosses the relevant thresholds, an SDLT return and charge can arise on the grant; rent-based leases use the net-present-value calculation. This is fact-specific and a matter for your tax adviser, but the headline for owners is: a roof lease is not a casual licence. It is a registrable land interest that can trigger SDLT, must be disclosed on sale, and needs mortgagee and (often) insurer consent before grant.

The sequence we run

Done in the right order, none of this delays a sound project. We run it as:

1. Roof and structure first — remaining membrane life and a BS EN 1991 loading assessment. These gate everything.
2. Title and finance — read the charge and covenants; open the lender-consent conversation early if a roof lease is contemplated.
3. Insurance — notify the insurer, confirm re-rating and any BESS conditions, and align cover where a third party owns the array.
4. Warranty — confirm the roof warranty position and bring in the manufacturer before fixing details are set.
5. Lease and tax structuring — rent-review interaction, dilapidations and reversion, SDLT and registration, drafted by property counsel.
6. Then commit capital and instruct works — with grid and planning running in parallel (planning and grid guide).

Get a free, no-obligation quote and we will map your specific consents and surveys before you commit a pound of capital.

Frequently asked questions

Do I need my lender’s consent to put solar on a mortgaged building?

Usually yes if you are granting a roof lease, and possibly yes for a landlord-owned array. A roof lease grants a third party a registrable interest in the lender’s security for 20–30 years, and almost every commercial mortgage requires prior written consent before you grant a lease out of the charged property. For a landlord-funded array you own outright, you may only need to notify under a material-alteration clause — but read the facility agreement, because breaching a covenant unknowingly can trigger default provisions.

Will solar increase my insurance premium?

It can, and you must notify your insurer regardless. Panels add value-at-risk and a new electrical failure mode, so the buildings cover may be re-rated and conditions imposed on certification and maintenance. The bigger conversation is battery storage: a co-located BESS introduces lithium-ion fire risk and some insurers exclude it or require specific separation, suppression and detection. Raise the array — and any battery — with your insurer before install, because non-disclosure of a material change can prejudice a future claim.

My roof has 10 years of life left — can I still install solar?

Yes, but you should re-roof and install in one project rather than fix a 25-year array to a roof you will have to replace underneath it. Removing and reinstating solar for a re-roof means paying twice for scaffold, access and labour, plus lost generation throughout. With under 15 years of membrane left, a single combined programme is usually cheaper per unit and lets you specify a roof covering designed for the array. Under five years, re-roof first.

What happens to the panels at the end of a roof lease?

It depends entirely on how the lease is drafted — which is why this is settled before signing. A well-drafted roof lease gives the owner a reversion of the array in working order at nil cost, or imposes a clear decommissioning-and-reinstatement obligation on the developer. The complication for owners is timing: a 25–30 year roof lease outlasts the occupational tenancies beneath it, so the array persists across multiple lettings and likely a sale. Every later occupational lease and sale contract must be drafted around the existing roof lease, or the unresolved reversion surfaces as a title query on the next transaction.