Buy Solar vs Rent a Roof (Free Solar): The Honest Maths

Every so often a leaflet lands promising you “solar panels for free” — no upfront cost, panels fitted next month, and lower bills from day one. It sounds like the risk-free version of going solar. It isn’t. These rent-a-roof arrangements are real, and for a small group of people they genuinely make sense. But the reason a company will fit thousands of pounds of kit on your roof for nothing is simple: they keep the money the panels make, and you keep only the crumbs. Here’s the honest maths on renting your roof versus buying the system yourself — including the catch that only shows up years later, when you try to sell or remortgage.

What “solar panels for free” actually means

There’s no such thing as genuinely free electricity generation — someone always pays for the panels. In a rent-a-roof deal, an installer or investor pays for and owns the system, and in exchange they lease space on your roof, usually for a long fixed term (commonly 20–25 years). You don’t buy anything, so there’s no £6,000–£8,000 outlay. In return you get to use, for free, whatever solar electricity your household happens to consume while the panels are generating.

These schemes were most common under the old Feed-in Tariff (which closed to new applicants in 2019), where the generous generation payments made the investor’s numbers work. Today they resurface as roof leases and power-purchase-agreement (PPA) style offers. The label changes; the structure doesn’t. The provider funds the kit because they collect an income stream from it — and that income is the whole point of the arrangement, for them.

Who keeps the money — and why it isn’t you

This is the part the leaflet skips. When you rent your roof out, the panels aren’t yours, so the financial upside flows to the owner, not to you.

• The export income is theirs. Any electricity your panels generate but you don’t use gets exported to the grid. Under the Smart Export Guarantee, the system owner earns for every exported unit — around 12p with Octopus Outgoing (cut from a rate that was 15p on 1 March 2026), or roughly 15p with Good Energy, as at July 2026. On a rent-a-roof deal you can’t claim the Smart Export Guarantee at all, because SEG is paid to whoever owns the MCS-certified system. Every unit you don’t use earns them money, not you.
• You only get the free electricity you actually use. Your benefit is limited to daytime self-consumption — the washing machine, kettle or hot water you happen to run while the sun’s out. If you’re out during the day, that’s a modest amount. A unit you use yourself is worth about 26p (the Ofgem price cap sits at 26.11p/kWh for July–September 2026), so it’s not nothing — but it’s a fraction of the total value the system produces.
• You don’t own an asset. When you buy, the panels are yours: they cut your bills for 25 years or more, and the paperwork sits with your home. On a rent-a-roof deal you’ve handed two decades of generation to someone else and kept a slice of daytime power.

The maths that makes these deals attractive to investors is exactly the maths that makes them poor value for you. If the numbers work well enough for a company to fund the whole thing and still profit across 25 years, they’d work even better with you keeping that profit — provided you can fund the install.

Buy vs rent: the honest comparison

	Buy outright	Rent a roof (“solar panels for free”)
Upfront cost	~£6,000–£8,000 for 4kWp (0% VAT to 31 Mar 2027, then 5%)	£0
Who owns the panels	You	The provider
Free daytime electricity	Yes — all of it	Yes, but only what you use while generating
Export income (SEG)	Yours to keep (~12p/unit, Octopus Outgoing, as at July 2026)	Kept by the provider — you can’t claim SEG
Typical annual benefit to you	~£400–£700 (self-use + export)	Often only ~£150–£350 (daytime use only)
Payback	~7–12 years, then years of near-free power	You never paid — but you never fully benefit either
Contract	None — it’s your kit	Long roof lease, commonly 20–25 years
Add a battery / change the system	Your choice	The provider’s kit — not your call
Effect on selling or remortgaging	Owned kit + documents; generally straightforward	Roof lease can complicate a sale or mortgage
Best for	Owners who can fund it and are staying put	Those who genuinely can’t fund it and will stay long-term

All figures are 2026 ranges and would be confirmed at a proper survey — treat none of them as a guarantee. The headline is the pattern, not the exact pounds: buying keeps the full saving; renting keeps a sliver of it.

The catch that shows up years later: selling and remortgaging

The financial gap is only half the story. The bigger long-term issue with renting your roof is what it does to your home.

Because the provider holds a lease over your roof, that lease is attached to the property, not just to you. When you come to sell, the buyer has to accept the lease and the panels along with the house. Some buyers are perfectly happy to; others aren’t, and a buyer’s solicitor will almost always raise enquiries about the lease terms, who’s responsible for the roof, and what happens if the provider goes out of business. It’s an extra thing to explain and negotiate at exactly the moment you want a clean, quick sale.

Remortgaging can be affected too. Mortgage lenders take a view on long leases over part of a property, and some are cautious about roof-lease agreements or want the lease to meet specific conditions before they’ll lend. It doesn’t make a sale or remortgage impossible — plenty complete without drama — but it adds friction, paperwork and the occasional deal that stalls. None of that arises when you own the panels outright: there’s no third party with a claim over your roof, just an asset with its warranties and certificates that transfers straight to the new owner.

This is the honest trade-off nobody hands you on the leaflet: a rent-a-roof deal costs you nothing today, but it can quietly cost you flexibility and simplicity for two decades.

Who rent-a-roof might genuinely suit

None of this makes renting your roof automatically wrong. It’s a different deal, and for the right household it can still be sensible — as long as you go in with eyes open:

• You genuinely can’t fund an install and won’t for years. If a £6,000–£8,000 system is simply out of reach and financing it isn’t sensible for you, some free daytime electricity is better than none. Renting the roof gets you a modest saving with no capital at risk.
• You’re confident you’ll stay put for the long haul. The sale and remortgage complications only bite if you move or refinance. A long-term stayer who has no plans to sell within the lease period sidesteps most of the downside.
• You’ve read the lease properly. Check the term, the provider’s obligations for the roof, what happens if they go bust, and — crucially — the exit clause and any fee to buy the system out or have it removed. If those aren’t clearly spelled out in writing, that’s your signal to walk away.

If you’re weighing this because money is tight rather than because you truly can’t buy, it’s worth first checking whether the sums work better than you think — our savings calculator and the cost breakdown show what a bought system realistically returns, and is solar worth it walks through the honest yes-and-no of the whole decision.

Our honest recommendation

Where you can afford it, buy the system outright. You keep the full bill saving, you keep the export income, you own an asset that cuts your bills for 25 years or more, and you keep your roof — and your future house sale — free of a long third-party lease. Yes, it means finding the money upfront, and yes, the payback takes roughly 7–12 years. But after that the generation is close to free, and every pound of value stays with you rather than an investor.

Rent your roof only if buying is genuinely out of reach and you’re a committed long-term stayer — and even then, read the lease line by line before you sign anything. The appeal of “solar panels for free” is real, but so is the reason it’s on offer: the person paying for the panels is the person who profits from them. Make sure that’s a fair swap for you, not just for them.

If you’d rather see what owning the system does for your own roof and usage, put your numbers into the savings calculator first, then let an MCS-certified installer’s survey confirm the detail. These are ranges, not promises — and the honest figure only ever comes from your own home.