Why commercial solar PV is a specialism of its own
Commercial Solar PV is an independent information site published by SEO Dons Ltd, registered at 71-75 Shelton Street, Covent Garden, London WC2H 9JQ, Company No. 16766013. It provides guidance on rooftop and ground-mounted solar PV systems for UK businesses, and covers commercial systems only. It is not an installer, and it does not cover domestic panels or general electrical contracting. The focus is deliberate.
Commercial solar is a different discipline from domestic solar. Where a house has a predictable load and a small array, a warehouse, factory or multi-let office has a complex half-hourly consumption profile, a G99 grid application, permitted-development and structural questions, and a six-figure capital decision that has to clear an IRR hurdle in front of a board. Getting that right calls for someone who models the load rather than guesses it, understands the tax treatment, and knows how a Distribution Network Operator connection works.
This guide's reader is usually the finance director, estates manager or owner-director who signs off the capex and fields the Scope 2 and ESG questions coming down the supply chain. That person has been cold-called by enough clipboard installers to recognise sales-speak on sight. What helps them is specifics first, honest limits, and numbers you can defend upstairs.
A model-driven approach
Every claim about generation, saving and payback should come out of a model built from your building's real data, not a per-square-metre estimate off a satellite image. The process runs in order:
- A good installer starts from your half-hourly meter data. Your supplier can provide the consumption record, and it reveals the shape of your demand, how much runs as steady baseload, and how much falls outside daylight hours. Roof area alone tells you little about the right system size.
- A good installer models the yield in PVSyst. Using your roof drawings, orientation, pitch and measured shading, annual generation is predicted properly rather than assuming a clear roof.
- Ask the installer to share the model. The yield file should go with the proposal, so you, your accountant or any third party can check the assumptions. A number you cannot verify is a number you should not sign against.
- The proposal should be specific. It should set out the system, generation, saving, and the funding options modelled side by side with an IRR each.
A good installer sizes for annual generation equal to 60 to 85 per cent of your current use, which keeps self-consumption high. To sketch the numbers for your building, use our savings calculator, and for full per-kWp pricing across the 30 kW to 2 MW range see our real-world UK pricing guide.
Accreditations and warranties
Accreditation is not a badge collection. Each certification governs a specific part of the work, and the combination is what lets a system qualify for the Smart Export Guarantee and keeps your buildings insurance in place:
- MCS commercial certification, which underpins SEG eligibility and confirms the install meets the recognised commercial specification.
- NICEIC Approved Contractor registration for the electrical work.
- RECC and TrustMark, the consumer-protection and government-endorsed quality schemes.
- IWA insurance-backed workmanship warranty, which protects the workmanship cover even if the installing company were no longer trading.
- ISO 9001, 14001 and 45001, covering quality, environmental and health-and-safety management.
Two warranties matter. The panels carry a 25-year performance warranty, so the manufacturer guarantees a defined output floor over that period. Separately, the workmanship should be covered by an insurance-backed warranty, which means the guarantee on the installation is underwritten by an insurer rather than resting on the installer staying in business.
Independent of any single manufacturer
A good installer is not tied to one panel maker, inverter brand or mounting system, and carries no manufacturer target to hit. An installer bound to a single product range will fit that range whether or not it is right for your roof, because that is what they are set up to sell. The panels, inverters and mounting should be specified for the building in question, on engineering and value grounds alone: a trapezoidal metal warehouse roof wants a different approach from a flat membrane office roof, and a factory load a different inverter strategy from an office.
Honesty, including when the answer is no
The most useful thing a specialist can tell you is when not to proceed, and it is the thing the market almost never says. A reputable installer will say plainly if your site does not suit solar. If the roof has only a few years of life left and would need replacing before a 25-year array could sit on it, they should say so. If your load profile means most generation would be exported at the low SEG rate rather than used on site, or a rural DNO connection would take 18 months, they should show you rather than keep a deal alive.
Honesty matters in the numbers too. A typical UK commercial install pays back in 5 to 8 years, with high-baseload factories and warehouses at the lower end and lighter-use offices and retail toward the top. The tax position should be spelled out correctly: commercial VAT is reclaimable for a VAT-registered business rather than zero-rated the way a domestic install is, and 100% Annual Investment Allowance lets a profitable company deduct the whole capex from taxable profit in the first year.
UK-wide coverage across every commercial sector
Commercial solar PV is relevant across the UK and across the full range of commercial building types. The engineering, finance and compliance change with the sector, which is why each has its own detailed guidance. The starting point is always the same: a desk feasibility from your meter data.
- Solar for warehouses and industrial units, where unshaded steel-portal roofs make the best canvas for commercial PV in the country.
- Solar for factories and manufacturing, where steady daytime load drives the strongest payback of any sector.
- Solar for offices, where daytime occupancy lines up almost perfectly with generation.
- Solar for retail and showrooms, with long trading hours and large roofs.
- Solar for agricultural and rural buildings, with unshaded south-facing barn roofs.
- Solar for hotels, pubs and leisure, where kitchens, laundry and pools drive evening demand.
- Solar for schools and public buildings, funded through Salix and the Public Sector Decarbonisation Scheme (closed: no application window since Phase 4 ended in November 2024).
How to get started
The first step is a desk feasibility, which needs no site visit. An installer needs your half-hourly meter data and a rough idea of your roof to give an honest read on whether solar makes sense and, if it does, an indicative size, saving and payback. If the numbers stack up, the next step is a full PVSyst model and a proposal that should be fixed-price, with cash, asset finance and a Power Purchase Agreement compared side by side.
To begin, request a quote or read the answers on our frequently asked questions page. A good installer will give you specifics and straight answers, and will say honestly if your site is not one they would recommend building on.