Is my site suitable for commercial solar?

What goes wrong, and what does it cost?

A site problem usually costs you a tender that is priced and then stalls, because an installer finds a tired roof, asbestos sheets or a missing landlord signature after the quotes are in.

The board approves a system, and then the roof turns out to be the real project.

• Skipping the structural survey. Zigaflow lists strengthening older flat roofs as a cause of delay ¹³.
• Fitting panels to a roof that is nearing replacement. If the covering must be replaced within the array's life, the array has to come off and go back on. Secured Engineers advises comparing re-roofing first against reinstallation ⁸.
• Treating asbestos cement as ordinary roofing. HSE says fibre cement sheets are fragile, and that all fixed roofs should be treated as fragile until a competent person confirms otherwise ³.
• Ignoring the 56-day prior approval. That is about eight weeks to add if found late ¹.
• Signing a PPA or roof sub-lease that outlasts the occupational lease. Charles Russell Speechlys flags the constraint ¹⁰.

Can my roof carry solar panels, and how much life should it have left?

A roof is suitable when an independent structural engineer confirms it can carry the array, and when the roof covering will last long enough that the panels do not have to be lifted off for re-roofing.

Beba Energy, an installer, says an independent structural engineer should confirm the roof can carry the load ⁷. It puts typical array weight at about 13 kg/m2, and says non-penetrative ballast can change that figure dramatically. Treat it as one supplier's number, not a rule.

A survey checks static, dynamic (wind, snow) and temporary load. The outcome is pass, pass with changes, or fail ⁷.

Panels typically last 20 to 30 years ⁹. If the roof covering will not, the array must come off and go back on, so check module and inverter warranties ⁸.

We found no public benchmark for roof life. Ask your engineer for a number in writing.

Can I put solar on an asbestos cement roof?

An asbestos cement roof, a type of fibre cement roof, can be refurbished for solar, but it must be treated as fragile and handled by a competent contractor, and the route is either over-cladding or removal and replacement.

HSE says falls through fragile surfaces, especially fibre cement roofs and rooflights, account for 22% of fatal falls from height in construction ³. Its roof work guidance, HSG33, names asbestos cement sheets among the largest single causes of roof deaths ⁵.

Removal rules matter for cost. HSE says carefully removing asbestos cement sheeting without breaking it up is non-licensed work. Where sheets will be substantially broken up, for example when a roof is dropped, it is notifiable non-licensed work that needs notification, medical surveillance and records ⁴.

NFRC guidance HSGS44 covers refurbishing such roofs, including removal and over-cladding ⁶. Ask each installer which route they price.

Roof works can sit in the same tender as the solar, as the Merlin Diesel Systems example below shows.

Do I need planning permission for solar panels on a commercial building?

In England, most non-domestic rooftop solar is permitted development rather than a full planning application, but PV that is not microgeneration needs prior approval from the local planning authority, which takes 56 days.

The Planning Portal sets the limits. Panels on a wall or pitched roof may project no more than 200 mm. On a flat roof the highest part may be no more than 1 m above the highest part of the roof. Roof-mounted equipment must be at least 1 m from the roof's external edge ¹.

Prior approval looks at design, appearance and glare on neighbours ¹.

The 1 MW capacity limit was removed from 21 December 2023, and all non-domestic changes are subject to prior approval ². Permitted development does not cover a listed building, a building within the grounds of a listed building, or a scheduled monument site ¹. These sites need a planning application, which Zigaflow says can add eight weeks ¹³.

Conservation areas: the sources disagree

Lewis Silkin (July 2025) says commercial installations in conservation areas need planning permission ⁹. The Planning Portal blog (December 2023) says the same change allows solar on roof slopes fronting a highway on Article 2(3) land, which includes conservation areas, subject to prior approval ².

We have not confirmed either reading against the legislation. If your site is in a conservation area, ask your local planning authority before you commit.

Other nations

Scotland, Wales and Northern Ireland have their own rules, which we have not sourced here. In Ireland, a 2022 regulation exempts solar on industrial roofs, with conditions, and limits the exemption to 300 m2 of roof aperture inside a solar safeguarding zone, so larger arrays there need planning permission ¹². Check for later amendments.

Can I install solar on a leased commercial building?

Often yes, but a tenant needs landlord consent and a lease long enough to repay the system, and the lease, not the planning rules, usually decides whether the project can start.

The Planning Portal says leaseholders may need permission from the landlord, freeholder or management company ¹. Lewis Silkin adds that a tenant should check the lease's alteration restrictions, that a multi-let building may need other tenants' agreement, and that contracts should cover removal and reinstatement at lease end ⁹. Take advice from your solicitor on your lease before you commit.

Consent usually runs through the lease's alterations clause ¹⁰. Electrical Review reports that landlords fear cost, admin and damage risk ¹¹.

On lease length, we found no public minimum. The logic is simple: the lease should run well beyond the projected payback. Our Merlin Diesel project shows a projected 6-year payback, so a short lease can rule a system out.

Where capital or tenure is the limit, compare capex, asset finance and PPA: capex, finance and PPA compared. Agree in writing who gets export payments and what happens at sale ⁹.

Which roof situation needs which check before a tender?

A sound modern roof can go straight to tender, while a fibre cement roof, a roof near the end of its life or a leased building each needs one specific check or decision first.

Four common situations, and what each needs before a tender.

The guide to comparing commercial solar quotes explains why every installer should price the same scope. A small, simple system on a sound roof may not need a managed tender.