In-roof vs on-roof solar: what is the difference?
On-roof solar mounts panels on rails above your existing tiles and is the cheaper, quicker and most common option. In-roof (integrated) solar sits flush within the roof, replacing the tiles underneath for a sleeker look, and is popular on new builds and re-roofs. In-roof costs more and can run slightly warmer, marginally reducing output.
How they compare
| Feature | On-roof | In-roof |
|---|---|---|
| Appearance | Sits above tiles | Flush, sleeker |
| Cost | Lower | Higher |
| Best for | Most retrofits | New builds, re-roofs |
| Cooling | Better (air gap) | Slightly warmer |
Which to choose
For most existing homes, on-roof is the practical, cost-effective choice and is what the typical £5,000 to £12,000 range assumes. In-roof makes sense if you are re-roofing anyway or want the cleanest look, and you accept the higher cost and a small output trade-off.
Frequently asked questions
- Is in-roof solar more efficient?
- No, slightly less, because the panels run a little warmer without an air gap behind them. The difference is small.
- Can I retrofit in-roof solar?
- It is best done during a re-roof. Retrofitting in-roof to an existing roof is more disruptive and costly than on-roof.
Related questions
Indicative estimates based on UK average data. Last updated 27 May 2026.