The financing decision for a commercial solar installation matters as much as the system design. The route you choose determines who claims the tax benefits, whether the asset appears on your balance sheet, who carries the maintenance responsibility and how much of the total lifetime return your business actually keeps. Two businesses installing identical systems can end up with very different financial outcomes depending on how they fund them.
This guide covers the main commercial solar financing UK options — outright purchase, asset finance, green loans, operating leases and Power Purchase Agreements — with an honest account of what each route costs, who it suits and where the trade-offs lie. If you’re at the evaluation stage, our commercial solar panel installations team can model the options against your specific circumstances.
Why the Financing Decision Matters as Much as the System Design
Three dimensions shift significantly depending on which route you take:
1. Tax Treatment
Outright purchase and asset finance both position the business as the owner of the asset, which means the right to claim capital allowances — typically the Annual Investment Allowance up to £1m — stays with you. At 25% corporation tax, that’s a meaningful reduction in your effective net investment in year one. However, under a PPA, the third-party owner claims the allowances, not you.
2. Balance Sheet Impact
The historical appeal of PPAs was that they kept the liability off the balance sheet. IFRS 16, which came into effect in 2019, changed this for many arrangements: PPAs that qualify as leases under the standard must now appear as right-of-use assets and corresponding liabilities. Whether a specific PPA qualifies as a lease under IFRS 16 depends on contract terms and requires an accountant’s review. It’s not automatic, but it’s common enough that the off-balance sheet assumption should be tested before it’s built into the business case.
3. Total Lifetime Return
Outright purchase delivers the highest lifetime return because you own all the energy savings, all the SEG income and all the tax relief from day one. A PPA delivers the lowest lifetime return but requires no capital commitment. Asset finance sits between the two, and the right answer depends on your capital position, your planning horizon and how your business evaluates competing uses of capital.
Our guide on commercial solar payback period UK covers how each of these variables plays into the overall investment calculation.
Outright Purchase (Capex): Highest Return, Highest Commitment
Paying for the installation from the business’s own capital is the most financially efficient route over the life of the system. You own the asset outright, claim all available tax relief in year one, retain all energy savings and SEG income, and carry no interest cost.
The AIA allows most businesses to deduct the full installation cost from taxable profits in year one, up to £1m. For projects above that threshold, a 50% First Year Allowance applies to the excess. At the 25% main rate of corporation tax, a £300,000 installation yields £75,000 of tax relief in the first accounting period after commissioning — reducing the effective net cost before a single unit of electricity is generated.
The constraints are capital availability and building tenure. Outright purchase makes most sense for businesses that own their premises or hold a long lease, have capital that would otherwise earn a return below the solar IRR, and want to maximise the lifetime value of the investment. Businesses with shorter leases or limited capital should consider the alternatives below.
Asset Finance and Green Loans: Ownership with Spread Capital
Asset finance — typically structured as a hire purchase agreement — allows a business to own the system while spreading the capital cost over an agreed term, most commonly seven to ten years for systems under £500,000. Legal ownership passes to the business at the end of the term for a nominal payment. Throughout the agreement, the business claims capital allowances as the beneficial owner, retains SEG income and keeps all energy savings.
Current commercial solar loan rates run at approximately 4.5 to 9% depending on project size, security and lender. Monthly repayments on a well-sized installation are typically covered by the energy savings from day one, meaning the financing is effectively self-funding from the point of commissioning. The business’s capital is preserved for other uses while the solar asset builds value on the balance sheet.
Green loans are a variant worth considering, with UK banks and sustainability-linked lenders offering rates in the range of 4 to 6% for qualifying low-carbon assets, which is at the lower end of the commercial lending market. NatWest, Bank of Ireland and a number of specialist lenders have active green business loan products. The rate advantage is modest but real, and accessing green finance can strengthen ESG reporting narratives for businesses with sustainability commitments.
For most commercial operators who want ownership without depleting working capital, solar asset finance UK is the practical middle ground between capex and a PPA.
Operating Leases: Predictable Payments Without Ownership
Under an operating lease, the lessor retains ownership of the system throughout the agreement. The lessee pays a fixed monthly amount and returns the asset at the end of the term. Capital allowances accrue to the lessor rather than your business; your lease payments are deductible as revenue expenses instead.
The practical implication is that you don’t get the year-one tax benefit of the AIA, but your monthly payments are fully expensed through the P&L rather than capitalised. For businesses that prefer simplicity in their accounting treatment and have no strong preference for ownership, an operating lease removes balance sheet complexity at the cost of a lower lifetime return compared to ownership routes.
Under IFRS 16, operating leases are no longer invisible on the balance sheet — the right-of-use asset and corresponding lease liability appear on the face of the accounts, though the P&L treatment differs from an owned asset. Make sure to confirm the accounting treatment with your auditors before selecting this route if balance sheet presentation is a consideration.
Power Purchase Agreements: Zero Upfront, Lower Total Return
Under a solar PPA commercial UK arrangement, a third party installs, owns and maintains the system on your roof. You buy the electricity it generates at an agreed rate, typically 15 to 25% below your current grid tariff, for the duration of the contract — usually 15 to 25 years. There is no upfront cost and no maintenance responsibility.
The trade-offs are material. Because the PPA provider owns the system, they claim the capital allowances — not you. You don’t receive SEG income, and the total saving over the contract life is considerably less than you would achieve through ownership, because you’re buying electricity from the PPA provider at a discounted rate rather than capturing the full grid displacement saving.
The power purchase agreement structure suits businesses that genuinely can’t commit capital, operate on shorter building leases that don’t align with a long ownership horizon, or want to trial solar at one site before committing to a full-estate programme. It’s also used in multi-site retail and logistics where the operational simplicity of a single maintenance-free contract across dozens of sites has real value.
On balance sheet treatment: many on-site PPAs qualify as leases under IFRS 16, meaning the right-of-use asset and lease liability appear on the balance sheet. This reversed a significant historical advantage of the PPA structure. Whether your specific arrangement qualifies depends on contract terms — specifically whether the customer has the right to direct the use of the identified asset. Get your accountant to review this before assuming off-balance sheet treatment.
If the PPA appeals primarily because of the zero upfront cost, it’s worth modelling asset finance alongside it. For many commercial operators, monthly asset finance payments are covered by energy savings from month one, which delivers the same effective cash flow position as a PPA while preserving the tax benefits and the higher lifetime return of ownership.
Our commercial solar panel installations team can produce a side-by-side financial model for your site across each financing route, which makes the trade-offs concrete rather than theoretical.
Comparing the Routes: A Framework for the Decision
The financing decision comes down to three questions: Can you commit capital? Do you own or have a long lease on the building? And how does solar compare to other uses of that capital in your business?
If you have capital and own the building: outright purchase delivers the best lifetime return. Claim the AIA, own the savings and the SEG income, and maximise the whole-life value of the installation.
If you want ownership but prefer to spread payments: asset finance or a green loan gives you the same tax treatment and lifetime return with lower upfront commitment. For most operators, this is the practical first choice.
If you have a shorter lease or prefer capital preservation: an operating lease or PPA removes the ownership complexity. Understand that you’re giving up tax relief and accepting a lower total return in exchange.
If no capital commitment is possible: a PPA is the route. Model it against the alternative of doing nothing, not just against ownership, and make sure the contract term aligns with your building tenure.
Whatever route you take, the conversation with your accountant and tax adviser should happen before you sign, not after. The solar lease vs purchase commercial decision has tax and accounting implications that vary by business structure, and the numbers in any installer’s proposal are only as useful as the assumptions behind them.
For a broader view of whether the investment makes sense before the financing question, our blog post onwhether solar panels worth it is a useful starting point. Our PV system and battery storage case study shows how the financing structure was factored into the investment case on a real commercial installation.
Get a quote and we’ll model the financing options alongside the system design so you can make the decision with real numbers in front of you.