Commercial solar can reduce a factory’s electricity costs and may also qualify for UK capital allowances. The tax treatment is important, however: HMRC specifically treats expenditure on solar panels as special rate expenditure, so solar panels do not qualify for 100% full expensing. Depending on the business and the expenditure, the Annual Investment Allowance (AIA) or the 50% special-rate first-year allowance may be relevant.
This article explains the current position for UK businesses. Capital-allowance claims depend on the taxpayer, ownership, expenditure and wider circumstances, so businesses should confirm the treatment with their accountant or tax adviser.
How HMRC treats solar panels
HMRC’s Capital Allowances Manual states that capital expenditure on the provision of solar panels is specifically designated as special rate expenditure. HMRC’s current guidance also lists solar panels among special-rate assets that cannot qualify for full expensing.
That distinction matters because full expensing provides a 100% first-year deduction for qualifying main-rate plant and machinery. Solar-panel expenditure is special rate, not main rate.
Annual Investment Allowance (AIA) and commercial solar
HMRC says special-rate plant and machinery may qualify for the Annual Investment Allowance. The AIA limit is currently £1 million. Where expenditure qualifies and sufficient AIA is available, AIA can provide a 100% deduction for qualifying expenditure up to the available limit.
The £1 million limit applies to the business’s qualifying expenditure and is not a separate £1 million allowance for each solar project. Businesses should therefore consider other capital investment made in the same period when discussing the available allowance with their adviser.
50% special-rate first-year allowance
For qualifying companies within the charge to Corporation Tax, HMRC provides a 50% first-year allowance for qualifying new and unused special-rate plant and machinery. HMRC specifically identifies solar panels as special-rate assets that may qualify. The remaining expenditure is generally added to the special-rate pool for subsequent writing-down allowances.
Why a blanket ‘25% tax saving’ claim is misleading
A solar installation should not simply be advertised as producing a guaranteed 25% tax saving. The actual tax effect depends on factors including the business’s taxable profits, Corporation Tax position, available AIA, the precise qualifying expenditure, ownership and financing arrangements, and other capital expenditure.
Capital allowances reduce taxable profits; they are not a cash rebate equal to a fixed percentage of the solar-system price. Any financial model should therefore show the tax assumption separately and have it checked against the company’s circumstances.
What about asset finance?
The availability and timing of capital allowances under asset-finance or hire-purchase arrangements depends on the legal and tax structure of the agreement and who is treated as owning the asset for capital-allowance purposes. Manufacturers should not assume that every finance agreement produces the same tax result.
If preserving working capital is important, see our commercial solar finance guide and ask your accountant or tax adviser to confirm the capital-allowance treatment of the proposed agreement.
Solar tax relief should support—not drive—the investment case
For a factory, the core commercial case should still be based on electricity consumption, expected solar generation, self-consumption, grid-electricity costs, project cost, finance and realistic operating assumptions. Capital allowances can improve the after-tax economics, but they should be modelled correctly rather than used as a headline guarantee.
For electricity savings, finance and payback considerations, read our commercial solar installation savings guide. For the wider project assessment, read our solar panels for factories UK guide.
Current HMRC position: summary
- Solar panels are specifically designated by HMRC as special rate expenditure.
- Solar panels therefore do not qualify for 100% full expensing.
- Qualifying special-rate expenditure may be eligible for the 50% special-rate first-year allowance for companies.
- Special-rate plant and machinery may qualify for the Annual Investment Allowance, subject to eligibility and the available AIA limit.
- The current AIA limit is £1 million.
- The tax outcome is company-specific and should be confirmed by a qualified tax adviser.
Tax information notice: This page provides general information based on current HMRC guidance and is not tax or accounting advice. Tax rules and individual circumstances can change. Obtain professional advice before making an investment or submitting a capital-allowance claim.
