Capital Allowances and Tax Benefits on Commercial Solar Panels
Solar panels are one of the most tax-efficient investments a UK business can make. The headline price of a commercial system is not the real cost: 100% capital allowances through the Annual Investment Allowance, reclaimable VAT and a business rates exemption typically cut the effective cost by a third. This guide explains each relief with worked examples, including the special rate rule most articles get wrong.
Quick Answer
UK businesses can deduct 100% of a commercial solar installation from taxable profits in year one through the £1m Annual Investment Allowance, worth 25% of the cost at the main corporation tax rate. VAT-registered businesses reclaim the 20% VAT, and in England the panels are exempt from business rates until at least 2035. A £40,000 system therefore has an effective cost of around £30,000.
Get commercial solar quotes with the tax relief modelled
Compare free quotes from MCS-certified commercial installers. Good commercial quotes show the post-AIA effective cost, not just the sticker price.
Every tax relief available on commercial solar
| Relief | Benefit | Who can claim |
|---|---|---|
| Annual Investment Allowance (AIA) | 100% deduction from taxable profits in year one, up to £1,000,000 of qualifying spend per year | Companies, sole traders and partnerships |
| 50% first-year allowance | 50% deduction in year one on special rate plant (including solar), no annual cap | Companies only, once AIA is used up |
| Writing down allowance | 6% a year on any remaining special rate balance | All businesses |
| VAT recovery | The 20% VAT reclaimed in full as input tax | VAT-registered businesses |
| Business rates exemption | Onsite solar and battery plant excluded from rateable value until 31 March 2035 | Occupiers in England (Scotland and Wales differ) |
This page is general information, not tax advice. Confirm your claim with your accountant: allowances interact with losses, group relief and accounting periods.
The Annual Investment Allowance: how the 100% deduction works
The AIA lets a business deduct the full cost of qualifying plant and machinery, including solar panels, mounting, inverters and installation labour, from taxable profits in the year the system is installed. The permanent limit is £1,000,000 a year, which covers all but the largest multi-site rollouts. Crucially, the AIA applies to special rate assets like solar at the full 100%, so it is almost always the right claim for a solar project.
Worked example: 50 kWp system, limited company
| Installed cost (ex VAT) | £40,000 |
| AIA claim (100%) | £40,000 |
| Corporation tax saved at 25% | £10,000 |
| VAT reclaimed (paid and recovered) | £8,000 |
| Effective year-one cost | £30,000 |
The same system saves roughly £10,000-£15,000 a year on electricity, so the post-tax payback drops to around 2-3 years. See our commercial solar cost guide for full pricing by system size.
Sole traders and partnerships claim the AIA against income tax instead of corporation tax, so the cash value of the relief depends on your marginal rate. The claim goes through your normal tax return for the accounting period in which the expenditure was incurred.
Solar is a special rate asset: the rule most guides get wrong
Since April 2012, HMRC has classed solar panels as special rate plant and machinery. That has two practical consequences that many articles, and some quotes, still get wrong:
- Full expensing does not apply at 100%. The headline full expensing regime covers main rate assets only. For special rate assets like solar, companies get the 50% first-year allowance, with the remaining 50% relieved through the 6% writing down allowance in later years.
- The AIA is the better claim for solar. Because the AIA covers special rate expenditure at 100% up to £1m, a solar project claimed under AIA gets full year-one relief anyway. The 50% first-year allowance only matters for companies whose AIA is already absorbed by other capital spend in the same year.
If a quote or a lender's appraisal assumes 100% full expensing on solar without mentioning the AIA, the tax numbers are wrong. Ask your accountant to model the claim order: AIA first, then the 50% first-year allowance on any excess.
VAT on commercial solar panels
The widely publicised 0% VAT rate on solar applies to residential installations only. Commercial installations are standard-rated at 20%. VAT-registered businesses reclaim that VAT as input tax in the normal way, so the real cost is the ex-VAT price. The cash-flow effect is temporary: you pay the VAT with the invoice and recover it in your next return.
Organisations that cannot recover VAT in full, such as charities, community halls and some mixed-use buildings, should price systems VAT-inclusive and may want to explore funded options. Our guides to solar for churches and community halls cover the sector-specific funding routes.
Business rates: the exemption until 2035
Rooftop solar used to increase a building's rateable value, which meant a higher business rates bill, a genuine deterrent for some occupiers. Since April 2022, eligible plant and machinery used in onsite renewable energy generation and storage, including solar panels and batteries, is exempt from business rates valuation in England until at least 31 March 2035.
Scotland and Wales run separate non-domestic rates systems with their own reliefs, so if your building is outside England, check the current treatment with your local assessor before you model project returns.
Export income and tax
Payments a business receives under the Smart Export Guarantee for surplus electricity are trading income and are taxable. In practice the sums are small: commercial systems are sized so most generation is consumed on site, because self-consumed electricity offsets grid power at 25-30p/kWh while exports earn a few pence. A well-designed system treats SEG income as a bonus, not the business case.
Funded and PPA systems: who gets the tax relief?
The reliefs on this page belong to whoever owns the system. If you take a capital-free route, where a funder installs and owns the panels and sells you the electricity through a Power Purchase Agreement, the funder claims the capital allowances, not you. Your benefit is the discounted electricity rate with no capital outlay. If the tax relief is valuable to your business, buying outright or financing the purchase usually beats a PPA. See the capital-free commercial solar section of our main guide for how the funding routes compare.
Commercial solar tax FAQ
Can you claim capital allowances on solar panels?
Yes. Solar panels qualify as plant and machinery for capital allowances. Most businesses claim the Annual Investment Allowance (AIA), which deducts 100% of the installation cost from taxable profits in year one, up to £1,000,000 of qualifying spend per year. Companies that have used up their AIA can claim the 50% first-year allowance instead, because HMRC classes solar panels as special rate expenditure.
Are solar panels tax deductible for a UK business?
Yes. A business that buys a commercial solar system can normally deduct 100% of the cost from taxable profits in the year of installation through the Annual Investment Allowance. At the 25% main rate of corporation tax, a £40,000 system reduces the year-one tax bill by £10,000. Sole traders and partnerships claim the same AIA relief against income tax.
Can you claim AIA on solar panels?
Yes. Solar panels are qualifying plant and machinery for the Annual Investment Allowance. The AIA covers special rate assets like solar at 100%, up to the permanent £1,000,000 annual limit, which comfortably covers almost every commercial rooftop installation. The claim is made through your normal corporation tax or self assessment return.
Is full expensing available on solar panels?
Not at the 100% rate. Full expensing gives 100% first-year relief on main rate plant and machinery, but HMRC classes solar panels as special rate expenditure, which gets the 50% first-year allowance instead. In practice this rarely matters: the Annual Investment Allowance gives 100% year-one relief on solar up to £1m of spend, so companies only fall back on the 50% first-year allowance once their AIA is used up.
Do businesses pay VAT on commercial solar panels?
Yes, commercial solar installations are charged VAT at 20%. The 0% VAT rate only applies to residential installations. VAT-registered businesses can normally reclaim the full 20% as input tax, so the effective cost is the ex-VAT price. Organisations that are not VAT registered, such as some charities and community groups, bear the full 20%.
Are solar panels exempt from business rates?
In England, eligible plant and machinery used in onsite renewable generation and storage, including solar panels and batteries, is exempt from business rates valuation until at least 31 March 2035. This removed the rateable value increase that previously penalised rooftop solar. Scotland and Wales set their own non-domestic rates rules, so check with your local assessor.
Is Smart Export Guarantee income taxable for a business?
Yes. SEG payments a business receives for exported electricity are trading income and are taxable in the normal way. The amounts are usually small next to the bill savings: self-consumed electricity is worth far more than exported electricity, which is why commercial systems are sized to match daytime demand.
Related guides
- Commercial solar panels UK: the complete guide
- Commercial solar panel costs by system size
- How to find a commercial solar installer
- Commercial solar panel grants and funding
- Solar panels and tax: the full HMRC picture
- Solar panels for farms
John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He researches every battery and inverter brand against manufacturer datasheets, MCS and Ofgem data, and feedback from the MCS-certified installers in our directory before publishing.
Sources
Compare Commercial Solar Quotes
Get free, no-obligation quotes from MCS-certified commercial installers, then let your accountant apply the reliefs above to the real numbers.