In-roof or on-roof?Pros and cons.

For a solar system on a pitched roof there are two ways to build. With on-roof, the modules sit on a substructure above the tiles. With in-roof, they replace the tiles and form the roof skin themselves. Both generate electricity from the same sunlight. Which system pays off depends mainly on the condition of your roof. If it is in good condition, on-roof is usually cheaper. If a new build or a roof renovation is coming up, it is worth comparing with in-roof.

Basics of the system are on the page in-roof solar system. The cost of an on-roof system is explained in the guide What does a solar system cost?.

The difference in brief

	On-roof	In-roof
Build	modules on substructure above the tiles	modules replace the tiles
Look	modules stand slightly above the roof	flush, calm surface
Suited to	existing roof in good condition	new build, roof renovation
Cost per kWp	lower	higher, but tile costs drop out
Ventilation	good	poorer, slightly lower yield
One-off payment under 30 kWp	CHF 360 per kWp	CHF 400 per kWp
Installation	quick	coordinated with roofer and plumber

Cost: when does in-roof pay off?

Per kWp, in-roof costs more than on-roof. The systems are more complex and the connections need sheet-metal work. A blanket price would be unreliable, because prices differ widely by system and roof. For on-roof, the guide values from the cost guide apply: CHF 24,000 to 30,000 for 10 kWp, CHF 33,000 to 42,000 for 15 kWp, each before subsidies.

It depends on what you are paying for anyway. For a new build or a roof renovation you need a new roof skin. Under the modules, the tiles and part of the roofer’s work drop out. The extra cost compared with a tiled roof is therefore what counts, and the full system price is the wrong yardstick. For a roof in good condition, this argument falls away. Then on-roof remains the more economical solution.

New build and roof renovation: the right moment

With a new build, the roof is not yet covered. Modules, roof build-up and electrical planning can be coordinated from the start, and some scaffolding and interfaces drop out. In a renovation, insulation and underlay can be renewed in the same step. It is important that architect, roofer, plumber and we plan together early. Changes are more costly with in-roof than with on-roof, because the modules are part of the roof skin.

Look: why in-roof appears calmer

In-roof modules lie in the plane of the roof. This gives a uniform surface without rails and gaps. With on-roof, the modules visibly stand above the tiles. If appearance matters to you, for example in a new build, in a historic core zone or in a house in a protected townscape, in-roof is often the better solution. Roof areas without modules are still covered with tiles, and we match the colour of modules and tiles.

For a protected building, solar tiles are also an option. These are small solar elements in tile form. They usually cost much more per watt than large-format in-roof modules.

Yield: ventilation makes the difference

Modules deliver slightly less electricity when warm. With on-roof, air flows under the modules and cools them. With in-roof, ventilation is poorer, the modules run warmer and deliver a little less. Good systems include an air channel under the modules. Then the loss stays small.

Orientation, tilt and shading have a bigger effect than the system. A south roof with on-roof gives more than a west roof with in-roof. With in-roof you also cannot place the modules freely, because they lie where the roof surface is. In the quote we show you the yield forecast for both options.

Watertightness and fire protection

The most important question with in-roof is watertightness. An in-roof system is watertight when three things are right: the system is tested and approved for the roof pitch, the connections at eaves, ridge, chimney and roof windows are executed cleanly, and there is an underlay membrane under the modules that drains water away. Very flat roofs are not suitable for in-roof.

The roof skin must also meet the cantonal fire protection rules. For solar systems, the fire protection information sheet of the VKF (Association of Cantonal Fire Insurers) applies. We choose only systems that are tested for this. We plan with the roofer and plumber so that system and roof form one whole. With on-roof, the existing roof skin stays unchanged, and watertightness depends on the fixings there.

Subsidies: in-roof brings a higher one-off payment

For systems under 30 kWp, Pronovo has paid no base amount since 1 April 2025. The payment is CHF 360 per kWp for attached and CHF 400 per kWp for integrated systems (EnFV Annex 2.1). For 10 kWp that is CHF 3,600 against CHF 4,000. A system counts as integrated if, besides generating electricity, it takes on a second function of the building envelope, which for in-roof is weather protection.

The CHF 400 difference does not cover the extra cost of in-roof. It does improve the calculation. Cantons and communes partly pay more on top. We register the system and submit the application. On request, we pre-finance the subsidy. More in the guide Subsidies for solar systems.

Permits

On roofs, suitably adapted solar systems need a notification, not a building permit (Art. 18a RPG). This applies to on-roof and in-roof. For cultural monuments a building permit is always required. In historic core zones and protected townscapes, the commune decides case by case, and a flush, uniform in-roof system often has better chances there than a visible substructure. We clarify this for your address and submit the documents. More on the procedure in the guide Solar system permits.

Which system when?

• On-roof suits you if the roof is in good condition, budget comes first and no special requirements apply to the look.
• In-roof suits a new build or roof renovation, high expectations of the look and a sensitive setting.
• Flat roof: Here a raised system is the solution, see Solar system on a flat roof.

For the electricity itself, the system makes no difference. With a battery storage unit and an EV charger you use more of it in your own home. The modules are described on the page PV modules.

We calculate it for your roof

On-roof or in-roof: the condition of the roof, its shape and your plans decide. We visit and check the roof, roof build-up and electrical system, the site visit is free. You then receive a binding quote within 72 hours, if you wish with both systems side by side, with yield, subsidies and payback.