Solar on a commercial roof works on different arithmetic from a house, and generally better. The reasons are worth understanding before you get quotes.
Last reviewed 4 Nov 2026.
Why the case is usually stronger than domestic
Consumption matches generation Most businesses operate during daylight, which is exactly when solar generates. A house is often empty when the panels are producing. This is the single biggest difference and it does most of the work.
A unit of electricity used on site is worth the full price you pay for it. A unit exported is worth considerably less. A business that uses most of what it generates gets far more from the same panels than a household does.
Larger roofs, better economics per watt Fixed costs are spread across more capacity.
Commercial electricity is a business cost, with the tax treatment that implies. Take advice from your accountant on capital allowances, because the position depends on your circumstances and we are not going to guess at it.
What is different from a domestic installation
Grid connection Commercial systems are almost always above the thresholds that let a domestic system connect simply, so a G99 application to the distribution network operator is required, before installation. Timescales vary and can be long in constrained areas. This is often the item that determines the project programme. See grid connection.
Roof structure A commercial roof, particularly a profiled metal or a flat membrane roof, needs a structural assessment. So does the age of the covering: fitting a twenty-five year system onto a roof with ten years left is a mistake that gets made regularly.
Half-hourly metering Most commercial supplies are half-hourly metered, which means you have detailed consumption data. Get it. A system designed against your actual half-hourly profile is a much better system than one designed against an annual total.
Planning Commercial premises do not always have the same permitted development rights as houses, and the position varies with the building and the location.
VAT The domestic zero rate does not apply in the same way to commercial installations. Take advice on your own VAT position rather than assuming.
Procurement Longer lead times, more documentation, and a contract that matters more than a domestic one.
What to get quotes on
- System size in kWp and estimated annual generation in kWh
- The generation modelled against your half-hourly consumption, showing what you would use and what you would export
- Grid connection route and status. Has a G99 application gone in, what is the expected timescale, and what happens if capacity is refused?
- Roof structural assessment, and the remaining life of the covering
- Warranty terms and who carries the workmanship risk
- Ongoing monitoring and maintenance, and what it costs
Ownership models
Buy it outright Simplest, best return, needs capital.
A power purchase agreement, where a third party owns the system on your roof and sells you the electricity at an agreed rate. No capital outlay, and you do not own the asset or get the full benefit. These can be reasonable and they can be poor. Read the term, the price escalator, the end-of-term provisions and what happens if you sell the building. Take advice.
In this section
Getting quotes
We are not taking quote requests at the moment. When you are ready, get quotes from more than one MCS-certified installer that does commercial work, and compare them like for like.