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Commercial Solar Finance UK · Independent
Q&A · Cost comparison

Cheapest commercial solar finance for UK businesses in 2026

On lifetime cost (the only fair comparison), capital purchase is decisively cheapest for profitable UK trading companies — typically £40-700k more saved over 25 years than alternative structures on a £200k system. The "cheapest" alternative depends on what specifically constrains your access to capital purchase.

The lifetime cost ranking (250 kWp, £200k system, 25 years)

RankStructure25-yr cumulative cash benefitvs cheapest
1Capital purchase£1.05mBaseline (cheapest)
2Operating lease£1.02m+£30k
3Green loan (7yr)£999k+£51k
4Finance lease (8yr)£986k+£64k
5Asset finance (7yr)£970k+£80k
6PPA (20yr)£548k+£502k

Capital purchase wins decisively. Each alternative trades lifetime cost for some operational benefit (working capital preservation, off-balance-sheet, operational outsourcing, etc.) — and the trade is typically worth it where the constraint is genuinely binding.

Why capital purchase wins on lifetime cost

Capital purchase has the lowest lifetime cost because there's no third party extracting margin from the project. Specifically:

  • No interest cost. Green loans charge ~7% APR for 7 years on the £200k = £53k of interest over the term. Capital avoids this entirely.
  • No lessor margin. Lease structures embed a 1-3% margin in the implicit rate. Operating lease lessors capture additional margin via lessor-side tax allowance use.
  • No PPA developer return. PPA developers price for 12-15% IRR on their capital. Over 25 years on a £200k system, that's £400-600k of margin you don't pay under capital purchase.
  • Direct FYA capture. Capital purchase captures the £25k year-1 FYA tax saving directly. Other structures may capture (green loan, finance lease, asset finance) or pass to a third party (operating lease, PPA).

When the cheapest isn't the right choice

Capital purchase is cheapest on lifetime cost — but cheapest isn't always best. Sometimes the operational, covenant, working capital, or strategic priorities outweigh £30-100k of lifetime cost difference. We routinely recommend non-cheapest structures where the constraint pattern justifies it. The cheapest structure is the right one only if no specific constraint binds harder than the cost difference.

Related questions

How much cheaper is capital purchase than green loan exactly?
£51k cheaper over 25 years on a £200k system, in our 2026 base case. The components: £53k of green loan interest minus ~£40k after-tax (interest is tax-deductible). Plus minor differences in O&M timing and special-rate-pool tail. Net: capital purchase saves about £30-65k over the 7-year green loan term, depending on rate and tax position.
Why is operating lease 25-year cumulative so close to capital purchase?
Counterintuitive but real. Operating lease only pays for 8 years (lease term), then the lessee captures full electricity savings for the remaining 17 years. Lessor doesn't bear O&M and inverter replacement costs that capital owner does (£70k+ savings). Net: operating lease lifetime is £30k more than capital — much closer than most people expect.
Is asset finance always more expensive than green loan?
Typically yes, by £15-25k over a 7-year term. Asset finance prices ~1-1.5 percentage points above green loan rates because of speed-of-decision and underwriting flexibility premium. Where speed isn't critical, green loan is cheaper. Where speed is critical (year-end FYA capture, opportunistic timing), asset finance's premium is worth paying.
Can I make PPA cheaper by negotiating the tariff?
Marginally. Tariff is one of 10 contract terms that affect lifetime cost. More leverage often comes from negotiating: contract length (15 yrs not 25), buyout right (year 7 not year 10), escalator (RPI not RPI+1%), and end-of-term ownership transfer. Get all terms negotiated, not just headline tariff.
Should the cheapest finance always be the recommendation?
No. We recommend the structure that best fits the client's overall situation, not just the cheapest. Operational simplicity, covenant headroom, working capital priorities, tax position, and contract horizon all matter alongside lifetime cost. The right structure is the one that wins on the client's specific constraint pattern — sometimes that's the cheapest, often it's not.

Continue reading

Capital purchase detailed page

The cheapest structure on lifetime cost. Mechanics, worked example, best fit.

Finance structure comparison

Side-by-side table for all structures.

Interactive calculator

Compute your specific project lifetime cost across all five main structures.

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