Capital Allowances & Tax Relief on Commercial Solar Panels
Annual Investment Allowance lets UK businesses deduct the full cost of commercial solar installation from taxable profits in year one — saving 19-25% of the installation cost before a single unit of electricity is generated.
Do Solar Panels Qualify for Capital Allowances?
Yes. Commercial solar panels qualify as plant and machinery under HMRC rules, making them eligible for Annual Investment Allowance (AIA) and full expensing. This applies to the panels themselves, the inverters, the mounting systems, the battery storage units, and the associated electrical infrastructure. HMRC confirmed this classification in its Capital Allowances Manual at CA23155.
Available Capital Allowances for Solar
Annual Investment Allowance (AIA)
Write off the full cost of solar installation against taxable profits in the year of purchase. AIA is available to virtually all UK businesses — sole traders, partnerships, and companies. The current £1 million annual limit means most commercial solar projects qualify in full.
A company paying 25% Corporation Tax on a £60,000 solar installation claims £60,000 AIA, saving £15,000 in Corporation Tax — effectively reducing the net installation cost to £45,000 before energy savings.
All profitable businesses — the most widely applicable relief
Super-Deduction (now expired)
ExpiredThe temporary super-deduction allowed companies to deduct 130% of qualifying expenditure. This expired on 31 March 2023 and has been replaced by full expensing for companies.
No longer applicable — included for reference only.
No longer available
Full Expensing
From April 2023, companies (but not sole traders or partnerships) can claim 100% first-year allowances on qualifying plant and machinery under full expensing. Solar panels qualify as plant and machinery. Unlike AIA, full expensing has no annual cap — making it relevant for very large installations.
A company investing £500,000 in a large commercial solar array claims the full £500,000 as full expensing, saving £125,000 in Corporation Tax at the 25% rate.
Companies (limited companies) with large installations exceeding £1 million
Tax Saving Calculator by Corporation Tax Rate
Your tax saving from AIA depends on your effective Corporation Tax rate. The table below shows the saving on a £60,000 installation.
| Tax Rate | Applies to | Tax saved on £60k install |
|---|---|---|
| 19% | Small profits rate (profits under £50,000) | £11,400 |
| 25% | Main rate (profits over £250,000) | £15,000 |
| 26.5% | Marginal relief rate (£50,000-£250,000) | £15,900 |
How to Claim AIA on Your Solar Installation
Confirm your installer is MCS certified
While MCS certification is not strictly required for AIA, it is a prerequisite for SEG payments and most grants. Use an MCS certified installer regardless.
Obtain a detailed invoice from your installer
Your invoice should itemise the cost of panels, inverters, mounting systems, battery storage, and installation labour separately. This may be relevant for some tax computations.
Include the claim in your annual tax return
AIA is claimed on your Self Assessment tax return (sole traders and partnerships) or Corporation Tax return (companies). Your accountant handles this as part of your annual accounts.
Claim in the year of purchase
AIA must be claimed in the accounting period in which the expenditure was incurred. Timing your installation to align with the start of your financial year maximises the cash flow benefit.
The Combined Incentive Stack
The most effective commercial solar investment combines all available incentives. For a profitable Midlands business investing £80,000 in a 70kW factory system:
Battery Storage Also Qualifies
Battery storage systems (Tesla Powerwall, GivEnergy, Fox ESS, Sigenergy) installed alongside or after your solar array also qualify for AIA as plant and machinery. This extends the tax relief benefit to your entire energy storage investment.
Sole Traders & Partnerships
AIA is equally available to sole traders and partnerships paying Income Tax. The saving depends on your marginal Income Tax rate — 20%, 40%, or 45%. For a higher-rate taxpayer sole trader, AIA on a £30,000 installation saves £12,000 in tax — a 40% reduction in effective cost.
Frequently Asked Questions
Can I claim AIA if I lease my business premises?
AIA is claimed by the party that owns the solar installation, not the building. If you own the solar system (even as a leaseholder), you claim AIA. However, leasehold installations may require landlord consent. Check your lease terms first.
Does AIA apply to the full installation including labour?
Yes. The Capital Allowances Act 2001 permits AIA on the full cost of plant and machinery including installation costs. This means labour, mounting systems, cabling, and inverters are all included.
What if my annual investment exceeds £1 million?
Expenditure above the AIA limit falls into the main pool and receives a Writing Down Allowance of 18% per year. Companies can also use full expensing for unlimited qualifying expenditure.
Can I claim AIA on battery storage added to an existing solar system?
Yes. Battery storage qualifies as a separate plant and machinery item and can be claimed under AIA in the year it is installed, regardless of when the solar panels were fitted.
How does AIA interact with a UKSPF grant?
Grant-funded expenditure reduces the amount on which you can claim capital allowances. If you receive a £15,000 grant on a £60,000 installation, you can only claim AIA on the net cost of £45,000. Your accountant will handle this calculation.
Is there any time limit on claiming AIA?
AIA must be claimed in the accounting period in which the expenditure is incurred. There is no retroactive claiming for previous years. Timing your installation to fall early in a financial year maximises the cash flow benefit of the tax saving.
This guide is for general information only and does not constitute tax advice. Always consult a qualified accountant or tax adviser before making capital investment decisions.
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Our team will calculate the full financial picture including AIA, 0% VAT, and available grants — so you see the true net cost and payback period before making any commitment.
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