A commercial or industrial roof is one of the best places for solar panels. The power is made during the working day, when most businesses use the most electricity, and the roof is already there. A 5,000 m² flat warehouse roof can carry roughly 350 to 600 kWp, about 322 to 552 MWh a year in London. Below: the benefits, with their sources, worked numbers for different roof sizes, and the checks to make before you ask for quotes.
- 100 to 200 kWp
- 200 to 500 kWp
- 500 kWp to 1 MWp
- over 1 MWp
What are the benefits of solar panels on a commercial or industrial roof?
Rooftop solar turns space you already own into electricity you use on site, at the time of day you need it, and in England it now has no planning size cap and pays no business rates. Every unit you use yourself is one you don't buy from the grid; the rest can be sold.
- Daytime power for daytime use. Offices, shops, workshops, cold stores and factories use most of their electricity in daylight hours, when panels generate. Power you use on site is worth what you pay for grid electricity.
- No land to buy or lease. The building, the access and the grid connection are already there.
- No planning size cap in England. Since 21 December 2023, permitted development for solar on non-domestic roofs has no 1 megawatt limit (SI 2023/1279). Conditions still apply, for example on protected land, so check with your council.
- No business rates on rooftop solar in England until 2035. Plant and machinery for on-site renewable generation, such as rooftop panels, is exempt from 1 April 2022 to 31 March 2035 (SI 2022/405, explanatory memorandum).
- Paid for what you export. The Smart Export Guarantee covers solar installations up to 5 MW in Great Britain; suppliers set their own rates.
- Measured renewable generation to report. The meter readings give real figures for energy and emissions reporting.
How much electricity can a commercial roof generate?
Roughly 0.07 to 0.12 kWp per m² of roof, times the yearly yield where the building is. On panels tilted at 10° facing south, PVGIS gives 920 kWh per kWp a year in London, 814 in Manchester and 772 in Glasgow.
| Roof, m² | Peak power, kWp | London, MWh a year | Manchester, MWh a year |
|---|---|---|---|
| 1,000 | 70 to 120 | 64 to 110 | 57 to 98 |
| 2,500 | 175 to 300 | 161 to 276 | 142 to 244 |
| 5,000 | 350 to 600 | 322 to 552 | 285 to 488 |
| 10,000 | 700 to 1,200 | 644 to 1,104 | 570 to 977 |
| 20,000 | 1,400 to 2,400 | 1,288 to 2,208 | 1,140 to 1,954 |
Why a range: on a completely clear 100 m by 50 m roof, south-facing rows spaced so they don't shade each other in midwinter carry 0.13 kWp per m² in our solar roof calculator. Real roofs lose space to rooflights, plant, fire routes, edge zones and weak areas, which is why we screen at 0.07 to 0.12 and measure each shortlisted roof before giving a firm figure.
Are commercial solar panels worth it?
Usually, when most of the power is used on site. Compare the panels' generation with your daytime electricity use: every unit used on site saves your import price, and exported units earn the export rate, which is usually lower. Your supplier can give you half-hourly meter data to make the comparison, and an installer can model it against the roof.
Two other things decide it: how long the roof will last (panels stay up for decades, so a roof due for replacement should be done first) and whether the grid connection can take any export.
Do solar panels work on metal roofs?
Yes. Profiled metal sheet and insulated panel roofs are common on warehouses and factories, and panels are fixed to them with rails or clamps that suit the sheet profile. Ask the installer to confirm the fixing method works with your roof sheet and its warranty, and check the condition of the sheets and fixings first.
What should you check before installing solar on a business roof?
- Structure. Frames and ballast add weight. A structural engineer should confirm the roof can carry it.
- Roof condition and remaining life. Repair or replace first if the roof is near the end of its life.
- Asbestos. The HSE's advice is that if a building was built or refurbished before 2000, you should assume it contains asbestos (HSE). Older cement roof sheets are a common place for it, so survey before any work on an older roof.
- Safe access. Fragile rooflights and roof edges need planned access for installation and maintenance.
- Grid connection. Talk to your distribution network operator early; larger systems need its approval before connection.
- Insurance. Tell your insurer before you install; insurers publish their own fire safety expectations for rooftop solar.
- Lease and planning. Tenants need the landlord's consent; check planning conditions for protected land and listed buildings.
How do you find which roofs are worth it across many buildings?
Screen them all with one method, then look closely only at the best. That is what our Solar Rooftop Analysis does: an area screen from building outlines and PVGIS yields, roof-by-roof analysis from LiDAR or a surface model, then a site report for the buildings you want to pursue. In central Novi Sad (the map above) the screen found 320 non-residential roofs of 1,000 m² or more, with room for roughly 68 to 116 MWp between them.
Rooftop solar in Serbia and the Western Balkans
The same roof makes more power further south. On 10° south-facing frames PVGIS gives 1,157 kWh per kWp a year in Belgrade, 1,162 in Novi Sad, 1,184 in Niš and 1,114 in Sarajevo, against 920 in London, so a 5,000 m² roof in Belgrade could make about 405 to 694 MWh a year. Serbia has no free national LiDAR, so a screen there starts from building outlines and adds roof shape from stereo imagery or a drone survey for the shortlist.
Sources
- Solar yields: PVGIS 5.3, European Commission Joint Research Centre, 1 kWp, 14% system losses, queried 13 November 2026.
- Planning: The Town and Country Planning (General Permitted Development etc.) (England) (Amendment) (No. 2) Order 2023.
- Business rates: The Valuation for Rating (Plant and Machinery) (England) (Amendment) Regulations 2022, explanatory memorandum.
- Export payments: Ofgem, Smart Export Guarantee.
- Asbestos: Health and Safety Executive, Find out if asbestos could be present in your building.