Commercial Solar Panel Installation — UK Costs, Grants & Guide

UK commercial solar installation costs range from £700/kW for very large (1MW+) ground-mount projects to £1,200/kW for smaller (50-100kW) rooftop installs. A typical 100 kW commercial system costs £80,000-£120,000 fully installed including DNO application, structural design, MCS sign-off, and 25-year warranty. Battery storage adds approximately £700 per kWh of storage. Most projects are funded outright via capital purchase, asset finance over 5 years, or zero-capital PPA.

From signed contract to energised system typically takes 8-16 weeks for a roof-mounted commercial install. The phases are: design and DNO application (3-5 weeks), procurement and lead times (4-6 weeks), on-site install (2-4 weeks for a 100-300 kW system), and commissioning (1 week). Larger projects above 500 kW or those requiring planning permission can take 4-6 months end to end.

Payback periods on commercial solar in the UK range from 4 to 9 years, depending on self-consumption ratio, DNO export agreement, and capital cost route. A factory or hospital with continuous shift demand and 90%+ self-consumption typically pays back in 4-6 years. A warehouse or office with weekday-only demand and 50% self-consumption pays back in 7-9 years. Battery storage shortens payback for sites with high evening or weekend demand.

Most commercial roof-mounted solar installations are permitted development under Class J of the General Permitted Development Order, provided the panels do not project more than 200mm above the roof slope. Ground-mounted arrays above 50 kW require full planning permission. Listed buildings and conservation area sites require listed building consent regardless of size. Your installer should handle any planning applications as part of the standard service.

Size commercial solar to consumption rather than to roof. A typical UK business uses around 50,000-200,000 kWh per year and needs a 50-200 kW solar system to offset 60-80% of grid imports during daylight hours. A good installer pulls your half-hourly meter data, models the system against actual demand, and recommends the size that maximises self-consumption rather than the largest system the roof can support.

The main UK commercial solar incentives are: the Annual Investment Allowance (100% first-year capital deduction up to £1m on solar PV as plant and machinery), and the Improving Farm Productivity grant (25%) for agricultural sites in England. The Industrial Energy Transformation Fund (IETF) closed in July 2025 with no successor. The Public Sector Decarbonisation Scheme (PSDS) has had no open application window since November 2024 — Phase 4 was its final phase — so public bodies now rely on capital budgets, PPAs or leases. A Power Purchase Agreement removes the upfront cost entirely.