Solar reflective membranes (SR): increasing performance of photovoltaic (PV) panels

The importance of rooftop solar applications has long been recognized by Sika because its solar reflective membranes (SR) can increase the performance of the photovoltaic (PV) panels. To assess and monitor their performance, Sika has built its own solar parks in several locations using different PV technologies.

19% more efficiency

In the case of PV panels with CIGS-Technology (Copper Indium Gallium Diselenide), the efficiency of the panels depends on direct solar radiation (approx. 80%) plus on indirect radiation, where the membrane type may have significant influence. The higher the value, the better it is. The initial CIGS Reflectance of Sika’s SR membranes is 95%, which improves the PV panel’s efficiency by 19% in comparison to a dark membrane or 9% in comparison to a light grey membrane.

Life Cycle Assessment (LCA)

To show the benefits from using Sika’s SR membranes, a Life Cycle Assessment (LCA) was made of the mechanically fixed roof build-up and the PV panels of the Sika solar park located in Stuttgart, Germany. The roof build up is 236 m² and consists of PV panels, Sika® Sarnafil® TS 77-20 RAL 9016 SR membrane, fasteners, mineral wool insulation and a vapor control layer. The LCA is from cradle-to-grave, which includes all life cycle stages from raw material extraction, logistics, manufacturing, installation, and use to disposal. A performance degradation of the PV panels of 0.2% per year was considered.

Results and conclusion

To assess the energy and carbon pay-back time of the roof build-up and PV panels, the energy produced by the CIGS-Technology PV panels with the Sika SR roofing membranes was compared with the costs to produce them both.

The Cumulative Energy Demand (CED) accounts for the consumption of energy resources, namely the total amount of primary energy from renewable and non-renewable resources. The Global Warming Potential (GWP) measures the potential contribution to Climate Change, focusing on emissions of greenhouse gases (e.g., CO₂, CH₄), which enhance the heat radiation absorption of the atmosphere, causing the temperature at the earth’s surface to rise

Cumulative Energy Demand (CED)

The energy costs from the whole life cycle of the roof build-up and the PV panels are surpassed by the gains in terms of energy produced by the PV panels after four years.


Global Warming Potential (GWP)

The carbon emissions from the whole life cycle of the roof build-up and the PV panels are surpassed by the gains in terms of avoided CO₂ emissions from the energy produced by the PV panels after three years.