If you’ve priced up solar and landed on a number somewhere between £6,000 and £17,000, the next question is obvious: how do you actually pay for it? Most UK households and businesses don’t have that sitting in a current account, so the finance route matters almost as much as the kit you choose. This guide compares the four realistic paths — cash purchase, a solar loan, 0% installer finance, and a power purchase agreement (PPA) or lease — with the true cost of each and where each one actually makes sense.
The starting point: 0% VAT changes the maths for everyone
Whatever finance route you take, residential solar and battery storage in Great Britain still qualifies for 0% VAT on both the equipment and installation labour, and that’s scheduled to run until 31 March 2027 before reverting to 5%. That’s a genuine saving baked into every quote you’re comparing — it isn’t a discount an installer or lender is offering you, so don’t let anyone present 0% VAT as “their deal.” It applies regardless of which of the four options below you pick.
What it does change is urgency. If you’re weighing up a loan against a PPA, the calculation you’re doing today is roughly 5% cheaper than the one you’ll be doing from April 2027, so borrowing costs and lease terms need to be judged against a closing window, not an indefinite one.
Option 1: Buy outright with cash
This is still the cheapest route over the system’s lifetime, because there’s no interest and no third party taking a margin on your export income.
Typical costs (installed, 2026):
| System size | Typical installed cost |
|---|---|
| 3 kW | ~£5,000 |
| 4 kW | £6,000–£8,000 |
| 10 kW | £13,000–£17,000 |
Add a battery and you’re looking at another £4,000–£8,000 (roughly £400–£700 per kWh of storage), or £8,500–£10,500 for something like a Tesla Powerwall 3 at 13.5 kWh.
With a typical UK yield of around 850 kWh per kWp per year (rising towards 1,050+ kWh/kWp in the sunnier south), and import electricity sitting around 25p/kWh under the Ofgem price cap, a well-sized 4 kW system is generally paying back in the region of 7–11 years, depending on how much of the generation you actually use versus export. Modern N-type panels (TOPCon, HJT or ABC cells) degrade at only around 0.4% a year and are commonly warrantied for 25–30 years, so a cash-bought system typically delivers 15+ years of essentially free electricity after payback. The main cost to plan for beyond that is a string inverter replacement at the 10–15 year mark, usually £500–£1,000.
Cash purchase makes most sense if you have the capital sitting in savings earning less interest than the effective “return” solar gives you, and if you’re not close to moving house within the payback window. For a full breakdown of how the sums stack up by system size, our solar panel payback calculator is worth running with your own roof numbers rather than a generic estimate.
Option 2: A dedicated solar loan
A solar loan is a standard unsecured (or sometimes secured/second-charge) personal loan used specifically to buy the system outright, which you then own from day one. You get all the benefits of ownership — full export income, no restrictions on adding a battery later, no resale complications — but you’re paying interest on top.
The economics depend entirely on the rate. At a representative APR in the 8–14% range typical for green home-improvement loans in 2026, a £7,000 system financed over 5 years might cost an extra £1,500–£2,500 in interest compared with cash. Over 10 years the interest bill roughly doubles that. This is the “hidden” cost most homeowners underestimate: a loan doesn’t just delay payback, it moves the payback date out by however many years the interest adds, sometimes by 2–4 years compared to buying outright.
Where a loan clearly beats waiting-to-save-up: if your current import bill plus loan repayment is still lower than your import bill alone would be without solar, you’re cash-flow positive from month one — you’re just capturing tomorrow’s savings today instead of after several years of saving. Several of the installers we track offer or can arrange this kind of finance directly, including Premier Electrical Renewables, who fit solar, battery and EV charging as a package, and YEERS across Yorkshire, who quote solar, battery, heat pump and EV installs together — useful if you’re financing more than one measure at once, since bundling can sometimes get a better blended rate than three separate agreements.
Always ask for the total amount repayable, not just the monthly figure or headline APR — that’s the only number that lets you compare a loan honestly against cash or a PPA.
Option 3: 0% (or low-rate) installer finance
Distinct from the loan above, a lot of installers now offer in-house or partner-lender finance advertised as “0% finance” or “buy now, pay later” for solar. It’s worth being precise about what this actually is, because “0% APR” schemes are rarely free money — the cost is usually built into the cash price you’d otherwise have been quoted, or the finance provider charges the installer a facilitation fee that gets folded into the headline price.
That doesn’t make it a bad option — it can be genuinely competitive, particularly over shorter terms (2–4 years) where the built-in cost is small relative to spreading a large bill. But you should always ask for the cash price alongside the 0% finance price for the same spec of system. If there’s a meaningful gap (more than a few hundred pounds on a £7,000 system), that gap is effectively the interest, just relabelled. If the cash and finance prices are identical, it genuinely is free credit and there’s little reason not to take it, since it improves your cash flow at no cost.
A few of our regional installer partners run these schemes as standard, including ECO Aim in Livingston covering Central Scotland, and Sola UK across Hertfordshire and the Home Counties — both worth asking directly for a side-by-side cash vs finance quote rather than assuming the 0% headline is the full picture.
Option 4: Solar PPA or lease (rent-free-roof models)
A power purchase agreement (or a solar lease) is a different animal entirely: a third party owns, installs and maintains the panels on your roof (or your car park, or your factory roof, for commercial sites), and you simply pay for the electricity generated — usually at a rate below your grid import price — or a fixed rental/service fee, typically over 15–25 years.
For homeowners, PPAs are far less common in the UK residential market than in the US, largely because the domestic 0% VAT incentive and relatively short payback periods already make ownership attractive, and because most UK lenders and installers prefer straightforward loan or cash sales. Where you do see them, read the small print on: who’s responsible for roof damage or leaks, what happens if you sell the house (the agreement typically has to transfer to the new owner, which can complicate a sale), and what the buy-out cost is if you want to end the agreement early.
For businesses, PPAs are a genuinely mainstream and often the dominant commercial solar finance route — no capital outlay, no balance-sheet asset, and a locked-in electricity rate that’s usually cheaper than grid import from day one, with the developer taking on the roof survey, structural checks, maintenance and inverter replacement risk. This is a completely different calculation from residential, driven by squeezing capex out of the deal rather than personal capital constraints. Solar Power Purchase Agreements breaks down how commercial PPA pricing and contract structures actually work, and Solar Asset Finance covers the lease and asset-finance alternatives if a PPA’s long-term commitment doesn’t suit your business. If you’re comparing that against straightforward commercial ownership, Commercial Solar Finance is a useful independent comparison point, and businesses that would rather explore grant-supported capex instead of any finance product should check Solar Panel Grants for Businesses before signing a PPA term.
Commercial buyers should also budget on a different cost base: installed commercial solar typically runs £900–£1,200 per kWp, meaningfully cheaper per-watt than domestic once you’re at rooftop-array or car-park-canopy scale — relevant whether you’re evaluating Commercial Solar Panel Installation for a standard rooftop or Solar Car Parks for canopy structures over a car park, where the PPA model is especially common because it turns unused asphalt into a rent-free revenue stream.
Farm and agricultural finance is a separate case
If you’re financing solar on a farm, don’t assume the Farming Equipment and Technology Fund covers it at some higher rate — it doesn’t, and treating it as a straightforward capital grant is a common and costly mistake. The relevant England scheme for farm solar is the Improving Farm Productivity grant, funding roughly 25% of eligible costs, with rates varying across the UK nations, so it’s worth checking your specific nation’s scheme before assuming a percentage. That makes an Annual Investment Allowance-led approach — claiming the tax relief and then financing or paying the balance — usually the more realistic route for row-crop or livestock operations, with typical payback still landing in the 2–4 year range for larger installations given the on-farm consumption profile. Solar Panels for Farms and Solar Panels for Barns both cover the funding landscape and realistic payback timelines for agricultural sites in more detail.
What the Boiler Upgrade Scheme won’t do
One correction worth making plainly: the £7,500 Boiler Upgrade Scheme grant is for air source (or ground source) heat pumps — it does not apply to solar PV or battery storage, and no scheme currently gives a flat cash grant for either on a standard owner-occupied home in England. If you’re financing a heat pump and solar together, treat them as two separate funding conversations: the heat pump grant reduces that invoice specifically, while the solar/battery spend is financed through one of the four routes above, with 0% VAT as the offset rather than a grant.
Which option actually fits your situation
- Have the cash and staying put 10+ years: buy outright. It’s the cheapest route, full stop, and the export income is entirely yours.
- Tight on capital but the sums still work with repayments added: a solar loan, provided you get the total-repayable figure and compare it honestly against the cash price.
- Want to spread cost with no real hidden cost: 0% installer finance — but only after confirming the cash price is genuinely identical.
- Running a business and want off-balance-sheet, zero-capex solar: a commercial PPA, accepting a lower per-kWh saving in exchange for someone else carrying all the risk and maintenance.
- A homeowner offered a residential PPA/lease: proceed carefully, check the resale transfer terms, and compare against a loan first — UK residential ownership economics are usually still better than renting your own roof.
Whichever route you’re weighing, get quotes from installers who’ll show you the cash price and the finance price side by side — that transparency alone tells you a lot about how competitive the deal really is. Local installers such as FLD Electrical in Swansea, Hazell Electrical in West Kent, and Green Linc Renewables in Lincolnshire — sorry, greenlincrenewables.co.uk — routinely quote both, which is the quickest way to see exactly what any 0% or loan offer is really costing you. And if you’re still deciding between a battery and a bigger array before you even get to the finance question, our solar battery storage costs breakdown and the wider cost of solar panels UK guide are the two pages to read first.