In-Roof vs On-Roof Solar Panels: Which Is Right for Your Home?

In-roof vs on-roof solar panels is one of the first decisions homeowners face once they’ve decided to go ahead with solar, and it’s easy to assume it’s just a style choice. It isn’t quite that simple. The two systems are fitted differently, cost differently, and perform slightly differently too, so it’s worth understanding what you’re actually choosing between before you get quotes.

In Brief

On-roof solar panels are fixed on rails above the existing tiles, making them cheaper and quicker to fit, while in-roof panels replace a section of tiles and sit flush with the roof for a neater finish, typically at a higher cost. On-roof systems also tend to run 5 to 10% more efficiently over a year, since the air gap underneath keeps the panels cooler.

We’ve recently completed one of each: an in-roof system in Sturminster Newton and an on-roof system in Gillingham. Both are genuinely good options, they just suit different homes and priorities.

What on-roof solar actually is

On-roof, sometimes called rail mounted or standard mounted, is what most UK homes have. Metal rails are fixed to the roof rafters, and the panels are then bolted on top of your existing tiles, sitting a few centimetres proud of the roof. The tiles underneath stay exactly where they are.

This is the quicker, more straightforward installation, and it’s the option most homeowners choose for a retrofit onto an existing roof.

What in-roof solar actually is

In-roof, also called integrated solar, sits flush with the roof rather than on top of it. A section of tiles is removed, a mounting tray and flashing kit go in their place, and the panels themselves become part of the roof surface. Once finished, there’s no visible gap or frame, just a clean run of panel where tiles used to be.

It’s a neater finish, but there’s genuinely more work involved, since roofers and installers need to coordinate around removing and replacing part of the roof structure itself.

How they compare on looks

This is where in-roof tends to win outright. Because the panels sit flush rather than proud, there’s no visible frame or gap underneath, which matters a lot on period properties or anywhere the roofline is on show. Our recent Sturminster Newton installation used all-black JA Solar panels with a GSE in-roof mounting kit specifically for this reason, the homeowner wanted a discreet finish that didn’t look bolted on.

That said, on-roof doesn’t have to look clunky either. Our Gillingham installation used all-black Aiko panels on an on-roof mounting kit, and the finish is still tidy and modern, it simply sits a little proud of the tiles rather than flush with them.

How they compare on performance

On-roof panels have an air gap underneath them, which helps them run a bit cooler. Solar panels lose a small amount of efficiency as they heat up, so that airflow gives on-roof systems a slight edge, commonly cited at somewhere in the region of 5 to 10 percent higher output over a year compared to an identical panel fitted in-roof on the same roof. In practice, for most UK homes that’s a modest difference rather than a dealbreaker, but it’s worth knowing about rather than discovering after the event.

How they compare on cost and practicality

On-roof is cheaper and faster to fit on an existing roof, since your tiles stay in place and there’s no additional flashing or waterproofing work involved. In-roof costs more as a retrofit, precisely because of that extra roofing work, but the calculation changes if you’re already having a full re-roof or building new. At that point you’re removing the tiles anyway, so in-roof can end up costing little more than on-roof while giving you the neater finish for free.

Which one suits your home

As a general rule:

• On-roof suits most straightforward retrofits, where budget and speed matter more than a completely flush finish.
• In-roof suits period properties, conservation areas, or anywhere the roofline is prominent and appearance is the priority, and it’s particularly worth considering if you’re already having roofing work done.

Neither is a wrong choice. We’ll always talk through your roof, your budget and what matters most to you as part of the initial survey, rather than defaulting to one or the other.

A couple of real examples

The Sturminster Newton project paired an in-roof system with a GivEnergy battery, giving the homeowner a discreet finish alongside strong self-consumption. The Gillingham project went with on-roof panels as part of a full renewable package alongside an air source heat pump and battery storage, prioritising a straightforward install over a completely flush look.

For general background on how solar panels work, typical costs, and what to expect from the technology itself, the Energy Saving Trust’s solar panel guide is a good independent resource. For savings specific to your own home, our guide on how much you can save with solar panels covers that in more detail.

A few questions we’re asked often

Can I switch from on-roof to in-roof later? Technically yes, but it means removing the existing system and mounting kit and starting again with in-roof works, so it’s rarely practical or cost effective. It’s worth deciding upfront rather than changing your mind after installation.

Does in-roof affect my warranty? Not with a reputable MCS certified installer. The panels themselves carry the same manufacturer warranty either way, it’s the mounting method that differs, not the product.

Is in-roof always necessary for listed buildings or conservation areas? Not always, but it’s often preferred, since the discreet finish tends to make planning approval more straightforward. We’ll advise on this as part of your survey.

Will bird proofing be needed either way? On-roof systems usually benefit from mesh guards to stop birds nesting in the gap underneath. In-roof systems don’t have that gap, so it’s less of a concern.

Thinking about solar for your home?

Whether you’re leaning towards in-roof, on-roof, or simply want a straight answer on which fits your property, we offer a free, no obligation site visit and quote. Get in touch and we’ll help you weigh it up.