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Theta In-Roof: Solar Panel Mounting System

The Theta In-Roof solar PV mounting system can comfortably integrate most solar PV panel sizes and types into roofs with wooden battens where the solar PV panel array is to be bordered by tiles, slates or similar. Solar PV panels can be mounted in portrait or landscape. The Theta In-Roof system includes everything needed to waterproof under and around the solar PV array including the transition between the tiles/slates and the PV array.

Roof Integrated Solar PV System

In-Roof: System Overview

The In-Roof system comprises of corrugated aluminium sheets mounted directly onto roof battens. Corrugated stainless steel adapters are then mounted on top of the sheets and secured directly to the roof. Adapters are used to secure module clamps which then secure the solar PV panels.

The aluminium sheets waterproof under the array, with the solar modules and tile/slate borders being installed over the top. A combination of aluminium flashings, pleated lead, rubber and foam is used to manage the transition between the tiles/slates and the solar PV panels.

In Roof Solar PV Mounting System


Case Study

In-Roof mounting systems are supplied to:

  • MCS Certified Solar PV Installers: Components are ordered piece by piece, selected based on the dimensions, number and orientation of the solar PV panels / modules and the characteristics of the mounting area. We can also quickly put together roofing system designs and confirm orders against the installation site measurements before shipping.
  • System Owners when installed as part of a full installation service: Bespoke In-Roof systems are designed and built to order based on the characteristics of the roofspace, client consultation and after a site survey. A full installation service includes a survey, a complete system design, the supply and installation of all hardware, MCS Certification and an overall system warranty.

The In-Roof system is suitable for:

  • Newbuilds: The In-Roof system is very simple to specify from architectural drawings and at any other early stage of a new build. Installing the In-Roof when the roof is being built makes good sense as additional roof coverings will not be needed in areas covered by solar PV panels. Designing the PV system early also means that the PV modules, cable runs, battening and roofing materials bordering the array can all be specified together.
  • Retrofit / Re-Roofing: Re-roofing using the In-Roof system instead of conventional tiles or slates is another practical and cost effective solution for in-roof solar panel mounting. The flexible and non-proprietary nature of the In-Roof system means that in many cases undamaged character tiles and slates can be reused and many different sizes, types and styles of solar panels can be chosen to suit both the appearance and the available space. Interesting and attractive roof integrated solar PV systems can be custom built and installed; maintaining character and continuity whilst combining the best of old and new roofing technology in the same roofspace.

In-Roof: System Design

The In-Roof system offers small numbers of parts, intuitive installations and quality components which all makes for a professional and clean installation. The In Roof system allows for lots of flexibility for both clients and installers in terms of system design and roof layout. There is also a wide choice of optional components that can be used together to suit different roof types and layouts. The system allows for the best way to integrate each system into it's roofspace to be decided by the system designer based on what best suits clients and roofspaces in terms of aesthetics, weatherproofing, shading and the technical requirements of the system.

In-Roof: Product Installation

Based on our own installation experience and feedback from other installers our advice is that a In-Roof installation is best installed by experienced roofers. The In-Roof installation is much closer to a traditional roofing installation than a standard solar PV installation would be. Transitions and detailed arrangements at ridges, hips and below the array especially in situations where solar PV panels are to cover the majority of the roofspace will likely need to be planned for.

In Roof: Mounting System Components

Adapter with a Module End Clamp

Close up sketch of an adapter with a module end clamp.

  • Module Clamps: Sized based on module depth, used to secure solar panels, secured into adapters.
  • Adapters: Secured to the roof through the metal sheets using sheet metal screws. Adapters come in portrait or landscape (3 lengths) and are used to secure module clamps.
  • Aprons: Installed under the PV array to transition rainwater to the lower tiles. Installed over the lower tiles and under the metal sheets.
  • Metal Flashings: Installed overlapping the metal sheets at the edges of the array. Bordering tiles or slates are installed over the flashings at the top and sides.
  • Metal Roofing Sheets: Available in 1000mm and 1500mm lengths x 1067mm wide, designed to be installed overlapping each other (min 200mm overlap).
In-Roof: Horizontal Section

Horizontal section showing a module clamp, an adapter, a mounting sheet and roofing screws.

  • Screws and Screw Covers: Used to attach metal sheets to roofing battens (4.5mm x 45mm roofing screws with covers). Used to secure adapters through the metal sheet into battens (sheet metal screws with washers).
  • Sealing Components: Used to further customise the transition between areas where the In-Roof system meets the tiles, slates or similar.

A full list of the different components with further information about each can be found here: In-Roof: Mounting System Components

In-Roof: Availability & Delivery

In-Roof components are mostly ready off the shelf with components for each order being packaged together into kits and delivered to site anywhere in the UK within 4-6 days.

Stock items can either be collected or sent out for next working day delivery when ordered before 2pm.

European Distributors / Installers / PV System Integrators

We also supply In Roof mounting systems to European distributors, installers and PV system integrators. Please contact us to discuss details or to request an In Roof components export pricelist (in Euros).

10 Year Guarantee

In-Roof: Guarantee

The In Roof: mounting system is provided with a 10 year manufacturers guarantee.

In Roof: Solar PV Roof Design & Component Selection

To generate a components list, structural report and quotation please fill in your project details and system preferences in the form below. A copy will then be forwarded to us and allocated to a designer to prepare. We will then come back to you with a list of components with prices, a structural report and detailed PV array measurements.

To fill out this form you will need:

Project Data:

Project description*:
Construction start date*:
Project address*:



Building Data:

Roof type*:
Roof length*(m):
Roof height from eaves to ridge*(m):
Pitch of the eaves*(°):
Building height (ground to ridge)*(m):
Roofing material*:
Batten spacing*:
Batten width*:
Batten height*:

PV Array Planning:

PV Panel / Module length*(mm):
PV Panel / Module width*(mm):
PV Panel / Module depth*(mm):
PV Panel / Module weight*(kg):
PV Panel / Module output*(Wp):
PV Panel / Module orientation*:
No. of PV panel / module rows*:
No. of PV panel / module columns*:
Total no. of PV panels / modules*:


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