BioSolar Roofs

A BioSolar Roof combines vegetation and solar PV technology in a single roof system. Depending on the project design, the system may support on-site renewable electricity generation, provide stormwater retention capacity and contribute to project-specific biodiversity objectives. 

Sika® NatureRoof PV combines roof mounted solar PV with the benefits of an extensive green roof, creating a BioSolar roof space that both generates renewable electricity and incorporates extensive green-roof planting designed to support project biodiversity objectives while providing stormwater retention functionality. 

The cooling effect associated with vegetated roof systems may help maintain lower operating temperatures for PV modules, which can contribute to improved electrical performance under certain conditions. Sika® NatureRoof PV can also be installed above a Sika® RetentionRoof Blue Roof System.

Suitable for use with any flat roof, Sika® NatureRoof PV utilises non-roof penetrating BioSolar mounting frames integrated within the green roof system through a modified drainage board. The aluminium support tray is positioned beneath the drainage board, with two aluminium C‑section frame locators protruding up through the filter fleece and growing medium. These locators provide the fixing points for the aluminium solar frames before the solar frame rails are installed.

Both South and East-West facing PV arrays at 10°, 15° or 20° can be used, and the Sika® NatureRoof PV system is ballasted down using the weight of the green roof growing medium.  The design loads for each individual roof are calculated based on the site location, elevation, topography, wind and snow loads to BS EN 1991-1 Eurocode 1. Actions on structures. General actions. Wind actions.

Sika® NatureRoof PV system designs follow the GRO Biosolar Best Practice Design Guidance considering best practice designs for fire safety, including distance from the external face of the building, abutting external walls, rooflights, SVP’s, lift over-runs etc.  Fire breaks will also be allowed between arrays as will maintenance access.  One specific benefit of the Sika® NatureRoof PV framing system is its ability to adjust the mounting height of the lower front edge of the PV panel, from 200mm upwards, enabling adaption to comply with any specific design requirements, such as those from the Department for Education (DfE) Construction Framework 2025.

Typically used in new build construction, Sika® NatureRoof PV is also suitable for retrofit/refurbishment applications with all systems specified with BBA Certification.  Sika roof systems have a life expectancy of at least 35 years’ or better.

When installed by a Sika® Verified or Certified Roofing Contractor with Sika® NatureRoof and Sika® SolarRoof Contractors the project will be eligible for a comprehensive Sika® System Guarantee.

For support in designing a BioSolar Roof please contact your local Sika® Area Technical Manager.