The Short Answer
We'd put panels on the roof unless you're re-roofing or building new. A 4kW system costs about £6,200 to £6,600 and pays back in 10 to 11 years on our model. The Energy Saving Trust puts a typical 4kWp of solar roof tiles at around £12,000 (November 2025 prices), which at the same output takes about 20 years to pay back.
The EST agrees: tiles are only really cost-effective if you're renovating the roof or building new, and if you're not, panels set into the roof may be more cost-effective. So if you don't like panels sitting on the roof, ask for an in-roof system and compare the price.
Three Different Things Called Solar Tiles
- Panels on the roof. Standard panels on brackets above the tiles. The cheapest option on the published figures below.
- In-roof (roof-integrated) panels. Full-size panels that replace a section of tiles and sit flush, sealed with flashing. Marley's SolarTile is one, despite the name: its 445W panel is 1134 x 1722mm, the size of an ordinary panel.
- Solar tiles or slates. Small units that replace individual roof tiles one for one. The EST says they're "hardly noticeable" and can fit awkward places, dormers and complicated layouts.
The EST's point that tiles make less electricity per square metre is about the third kind; in-roof panels are ordinary-size panels. Check which one a quote is for before comparing.
What They Cost
| 4kW system | Cost | Payback at £599 a year (our model) | Source |
|---|---|---|---|
| Panels on the roof | £6,200 to £6,600 | 10 to 11 years | DESNZ, 2025/26 |
| Solar tiles at 1.5 times panels | £9,300 to £9,900 | about 16 years | EST's ratio, DESNZ panel costs |
| Solar tiles, EST's typical price | £12,000 | about 20 years | EST, November 2025 |
| In-roof panels | No published figure | Depends on the price | Ask for in-roof and on-roof prices |
The EST says tiles are normally about 1.5 times the cost of panels. Paybacks use our model's £599 a year for 4kW in central England. The EST's tile price excludes removing old tiles and scaffolding. On a re-roof, the sum that matters is the extra over ordinary tiles, because you'd pay for the roof anyway.
Price Your Own Roof
1. What size system?
The Energy Saving Trust says the average home system is around 4.5 kWp, on 20 to 30 square metres of roof. Bigger systems need more roof area.
2. Panel type
Solar tiles look tidier but cost more: the Energy Saving Trust says they normally cost about 1.5 times as much as panels, which is what we use.
3. Battery storage
A battery stores spare daytime solar to use later, lifting the share you use at home from 26% to 42% with 5 kWh or 56% with 10 kWh, for this size in a home using Ofgem's typical 2,500 kWh a year.
Estimated installed cost
£6,200 to £6,600
Panels from DESNZ's figures for 2025/26 MCS installs: the median of all installs to the mean for homes, covering the equipment, fitting, connection and VAT (0% on solar until 31 March 2027).
Cost breakdown
- Solar panels + installation
- £6,200 to £6,600
- Battery storage
- None
- Total (0% VAT)
- £6,200 to £6,600
Bill savings
£263 / year
999 kWh self-used at 26.32p
SEG export income
£336 / year
2,801 kWh exported at 12p
Total annual benefit
£599 / year
Payback period
10.4-11.0 years
25-year net profit
+£7,776
Want a real quote for your home?
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Based on the Ofgem price cap for 1 October to 31 December 2026 (26.32p/kWh) and Octopus Outgoing SEG rate (12p/kWh), on our estimate of 950 kWh a year per kW for a south-facing roof in central England, with the share used at home from BRE's SAP 10.2 self-use formula for this size in a home using Ofgem's typical 2,500 kWh a year (26% without a battery, 56% with 10 kWh, taking 80% of a battery as usable, our assumption). For the 10 kWh battery we use the Energy Saving Trust's £5,000 to £8,000 for battery storage, which gives no size; solar tiles at about 1.5 times the panel price are its ratio too, and the 5 kWh battery's price is our estimate. The 25-year figure holds prices flat, uses the middle of the cost range and deducts one replacement inverter at £800, the Energy Saving Trust's figure (it says inverters typically need replacing every 10 to 15 years, so you may need two). For a region- and orientation-aware estimate, use our full solar ROI calculator.
Output
In-roof panels needn't give up output. Marley publishes 23.6% efficiency for the 445W all-glass SolarTile, which puts 445W into a 1.885 square metre aperture, about 236W per square metre. One small loss: panels set into the roof don't have air behind them and run warmer. Marley gives a power temperature coefficient of -0.29% per degree, so a panel 10 degrees hotter makes about 3% less at that moment.
True tiles do give up output for their size. The EST says they typically produce only about 80% of the electricity of the same area of panels, though they can often cover more of the roof.
When Tiles Make Sense
- You're re-roofing or building new. The EST's main case for tiles.
- Planning. The EST says tiles could be a good option to comply with planning requirements. Listed buildings need consent. Ask your council before you buy.
- You care about the look enough to pay for it, in our view: start with in-roof panels, which the EST says may be more cost-effective than tiles.
Repairs and Warranties
The case against anything built into the roof is repairs: a fault becomes a roofing job as well as an electrical one. Ask who'd do it and what it would cost. Marley gives the 445W SolarTile a 15-year systems warranty for compatibility and weathertightness and a power warranty of 95% at 10 years and 87% at 30; quotes can blur the two. The EST says some tiles are designed to last 40 years with a 25-year warranty, and still need maintaining. Panels on the roof, the EST says, should last 25 years or more.
What You Don't Need
- Tiles on a sound roof you're not replacing, in our view; in-roof panels give the flush look and, the EST says, may be more cost-effective.
- Swapping working panels for tiles. The EST says it wouldn't be very cost-effective.
Whatever you choose, use an MCS-certified installer with MCS-certified products: the EST notes not every tile is registered, and an export tariff may require it. Next: solar costs and how many panels you need.
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