Commercial solar calculator — system size, capex, payback after grants.
Enter your annual electricity spend and sector. The calculator estimates the system size that fits your demand, capex at 2026 UK prices, year-one savings, and post-grant payback. No email required, no obligation. For a properly modelled financial case run against your half-hourly meter data, the free funding review takes the next step.
Want a properly modelled case?
The calculator uses sector averages. The free funding review uses your actual meter data, real installer quotes and live grant windows.
No obligation. We don't charge for grant scoping.
Funding by asset class
The allowance depends on the asset, and most pages on this topic get it the wrong way round. Solar PV is special-rate expenditure (HMRC Capital Allowances Manual CA22335), so the 100% year-one route is the Annual Investment Allowance — Full Expensing is a main-rate measure and does not reach it. Battery storage, EV charging and heat pumps are Heat pumps for space or water heating are special-rate: AIA, then the 50% FYA. Standalone batteries are probably main-rate (full expensing for companies), but HMRC has no specific guidance; confirm with your adviser.
- heat pump capex for commercial buildings
Special-rate integral feature: AIA up to £1m, then the 50% special-rate first-year allowance for companies; full expensing does not apply.
- commercial battery storage costs and ROI
Probably main-rate plant (HMRC has no specific guidance, so confirm with your adviser). Stacks with solar for self-consumption.
- what commercial solar costs per kWp
Capex bands per kWp before any relief.
- rooftop solar on industrial premises
Large roofs, high daytime load — the strongest case.
- the Annual Investment Allowance explained for solar
Solar is special-rate, so AIA is the 100% year-one route.
Find out which 2026 schemes your site actually qualifies for
- 1. A short written funding note naming every scheme your site qualifies for in 2026 — and the ones it does not.
- 2. Indicative system size and a capex band for your roof.
- 3. Year-one tax treatment per asset in £ — solar is special-rate expenditure, so the route is the Annual Investment Allowance; heat pumps for building heating are also special-rate integral features, and standalone battery storage is probably main-rate plant (HMRC has no specific guidance, so confirm with your adviser). Most pages get this the wrong way round.
- 4. Projected SEG export revenue at current rates.
- 5. Any red-flag eligibility or DNO issues we can see up front.
Covers solar PV, battery storage, EV charging and commercial heat pumps — separately or as one bundled project. If your project is a heat pump or a battery rather than a roof, say so in the message box and the note is written against that asset instead.
- · We do not pass your details to multiple installers.
- · We do not run a lead auction, and your phone number is optional.
- · No marketing lists, no unsolicited calls.
- · We are an independent funding information service — not an installer.
Commercial solar cost & ROI
What commercial solar actually costs in 2026, what it returns, and how the numbers are built — installation, payback and live calculators.
Pillar guideCommercial solar cost guideReal 2026 pricing by system size and building.- Commercial solar panel costCost per kWp and per-panel pricing.
- Solar installation costWhat the install line covers and costs.
- Commercial solar payback periodTypical payback after the 2026 stack.
- Commercial solar installationThe end-to-end installation process.
- Commercial solar companiesHow to choose and vet an installer.
- Commercial solar maintenanceO&M cost, cleaning and ROI protection.