Solar finance vs paying cash: which wins?

If you have the money sitting in the business, the obvious question is whether to spend it on a commercial solar system or borrow against it. There is no universal answer. Cash gives you the lowest lifetime cost; finance keeps that capital working elsewhere. The decision turns on your cost of credit, what else your money could earn, and your tax position. This guide sets out the honest comparison so you can decide whether to lease or buy solar with the numbers in front of you.

The cash benchmark: lowest lifetime cost

Paying cash is the cheapest the project will ever be. There is no interest, no arrangement fee, and no lender margin. You own the system from day one, and ownership is where the value sits.

As the owner you claim the capital allowances yourself. Solar PV is special-rate (integral-feature) expenditure, so it qualifies for the Annual Investment Allowance at 100% on up to £1m of qualifying spend in the year, with a 50% first-year allowance on anything above that. It does not qualify for 100% full expensing — that relief is for main-rate plant only — but the AIA still lets most businesses write off the whole system in year one, and both reliefs are permanent. You also keep the Smart Export Guarantee income on every unit you send back to the grid.

So the cash route is the benchmark every other option is measured against. The real question is whether the benefits of financing justify paying more than this floor. Our capital purchase page walks through what owning outright looks like in practice, and the cost guide sets out typical commercial system pricing.

What financing actually costs

Financing adds a cost of credit on top of the system price. Spread over a five- to seven-year term, a commercial solar facility typically adds somewhere in the region of 8% to 20% to the headline price across the life of the agreement, depending on covenant, term and deal size. That is the premium you pay to keep your cash.

The figure that matters is not the headline interest rate but the total cost of credit — the sum of every payment over the term, minus the amount borrowed. Two deals with the same rate but different fees or terms can land in very different places. Run your own numbers through the finance calculator before you compare anything.

The other half of the financed equation is the saving. A well-sized commercial system generates electricity that displaces grid imports at 25p to 35p per kWh, plus export income on the surplus. On most projects the monthly energy saving plus export covers the monthly repayment, often with money to spare. When the saving exceeds the repayment, the system is effectively paying for itself out of the bills it removes — and you have kept your capital intact.

Opportunity cost: what your cash could be doing

This is where cash stops being the obvious winner. Spending £150,000 on solar means £150,000 you cannot put into stock, equipment, hiring, or a margin-generating project. If that money would earn the business 15% to 25% return on capital employed, tying it up in a roof that “only” delivers a 12% to 18% energy return may be the worse trade.

Finance lets you keep the capital deployed where it earns most while still capturing the energy saving. For a growing business, that flexibility is frequently worth more than the interest saved by paying cash. For a business sitting on idle reserves earning little, cash makes more sense. The honest test is simple: if your return on capital comfortably beats your cost of finance, finance; if it does not, pay cash.

Comparing net of allowances and tax

A like-for-like comparison has to be made after tax, not on the sticker price. The routes differ in who claims the allowances:

• Cash, hire purchase or an equipment loan — the business owns the asset and claims the capital allowances itself. HP and loans pay the VAT up front, which a VAT-registered business reclaims in the normal way.
• Finance lease — the lessor usually owns the asset and claims the allowances, passing the benefit back through lower rentals (unless it is a long-funding lease). The rentals are deductible against profits, and the VAT is spread across the rentals rather than paid up front.
• Operating lease — no allowances for you, but the rentals are fully deductible as an operating cost.

Hire purchase is the route most cash-rich businesses overlook. It keeps ownership and the allowances with you, exactly like a cash purchase, but spreads the outlay. For a profitable company the first-year allowance can offset a large slice of the cost, and on HP you capture that relief while still holding onto your cash.

The 2026 accounting change

From accounting periods beginning on or after 1 January 2026, revised FRS 102 brings most leases onto the lessee’s balance sheet as a right-of-use asset and a lease liability, with short-term and low-value leases exempt. Previously, operating leases stayed off balance sheet, which some businesses used to protect borrowing covenants. That advantage largely disappears under the new rules. Cash and hire purchase already sit on the balance sheet, so for asset-heavy comparisons the gap between routes narrows. Factor this in if a banking covenant is part of your decision.

So, finance or buy solar panels?

A reasonable rule of thumb:

• Pay cash if you hold genuine surplus reserves earning little, your return on capital is modest, and you simply want the lowest lifetime cost.
• Finance if your capital earns a strong return elsewhere, you want to preserve working capital, or you would rather match the cost to the energy saving the system produces each month.
• Use hire purchase if you want the ownership and tax position of a cash purchase without the up-front hit — for many trading businesses this is the sweet spot.

Whichever way the numbers fall, size the system to your daytime load first. A right-sized system that self-consumes most of what it generates beats an oversized one that exports cheaply, regardless of how you pay for it. If you are also weighing a third-party-funded route, note that under a PPA the funder keeps both the allowances and the export income — see our comparison of asset finance versus a PPA for why ownership usually wins over the long run.

Make the comparison on your own numbers

Cash wins on lifetime cost; finance wins on keeping capital working; hire purchase often gives you most of both. The right answer depends entirely on your figures, so model it properly before you commit. Tell us the system size, your tax position and what your capital earns elsewhere, and we will request your no-obligation quote and show you the cash, HP and lease routes side by side, net of allowances, so you can choose with confidence.