Commercial solar is one of the strongest capital investments a business can make in 2026. With electricity prices remaining high, 100% tax deductions through the Annual Investment Allowance, and business rates exemption on rooftop solar confirmed until 2035, the financial case is compelling. East Anglia businesses benefit from above-average solar irradiance and large roof areas ideal for maximising generation. Here is a complete breakdown of costs, returns, and tax benefits.
The Business Case at a Glance
Tax Benefits for Businesses
Annual Investment Allowance (AIA)
Businesses can deduct 100% of the solar installation cost from taxable profits in Year 1, up to £1 million. For a company paying 25% corporation tax, this effectively reduces the net cost of a £50,000 solar system by £12,500. The AIA applies to the full system cost including installation.
Business Rates Exemption
Rooftop solar installations on commercial properties are exempt from business rates until at least 2035. Without this exemption, a 100kW system could attract £2,000-£4,000 per year in additional rates. This exemption makes the investment even more attractive.
Reduced VAT on Energy
Businesses pay VAT at 20% on solar installations (unlike residential 0% VAT), but this is reclaimable as input VAT for VAT-registered businesses, making the effective cost the same as the net price.
Commercial Solar Costs by System Size
| System Size | Cost Range | Annual Generation | Annual Savings | Payback |
|---|---|---|---|---|
| 10 kW | £8,000 - £12,000 | 9,500 - 10,500 kWh | £2,850 - £3,680 | 2.5-4 years |
| 20 kW | £14,000 - £20,000 | 19,000 - 21,000 kWh | £5,700 - £7,350 | 2-3 years |
| 30 kW | £18,000 - £27,000 | 28,500 - 31,500 kWh | £8,550 - £11,025 | 2-2.5 years |
| 50 kW | £27,500 - £40,000 | 47,500 - 52,500 kWh | £14,250 - £18,375 | 1.5-2.5 years |
| 100 kW | £50,000 - £75,000 | 95,000 - 105,000 kWh | £28,500 - £36,750 | 1.5-2.5 years |
| 250 kW | £112,500 - £175,000 | 237,500 - 262,500 kWh | £71,250 - £91,875 | 1.5-2 years |
Costs shown are net of VAT (reclaimable by VAT-registered businesses). Savings assume 70% self-consumption at 24-28p/kWh with surplus exported via SEG. Actual costs depend on roof type, access, and system specification. Surplus generation can be exported via the Smart Export Guarantee for additional income.
Economies of Scale
Larger commercial systems benefit from significantly lower costs per kWp. While a small 10kW system might cost £800-£900 per kWp, a 100kW+ system typically costs £600-£700 per kWp. This is why larger roof areas deliver faster payback periods and higher overall returns.
Case Study Scenarios
Warehouse / Distribution Centre
Large flat roofs make warehouses ideal for solar. High daytime electricity consumption from lighting, refrigeration, and equipment means excellent self-consumption rates of 70-90%.
Office Building
Offices have strong daytime demand from IT equipment, lighting, and air conditioning. Solar generation aligns well with 9am-5pm consumption patterns, delivering 60-80% self-consumption.
Farm / Agricultural Buildings
East Anglia farms have large south-facing barn roofs ideal for solar. Energy-intensive operations like grain drying, milking parlours, and cold storage benefit from daytime solar generation. Diversification income from surplus export adds further value.
