Rooftop solar district heating plant

Brief

With its 206,635 inhabitants, Geneva is the second-largest city in Switzerland and known for being a centre of diplomacy and international relations. Furthermore, since the end of 2020, it is home to an impressive solar district heating plant, which went beyond expectations in terms of energy delivery and has proven to be an effective carbon free solutions for the city’s district heating system.

TVP Solar and the Geneva utility SIG published the performance results of the SolarCAD II – Solar District Heating Plant after 2 years in operation. The solar thermal plant has exceeded expectations by delivering 10% over the estimates and the results are key to duplicating the model across Switzerland and beyond.

Technology

The TVP High-Vacuum Flat Plate collectors supply 100% carbon-free thermal energy at more than 80°C all year round, even in winter when the collectors were covered by snow. The solar thermal plant directly injects the produced heat into the largest district heating network in the canton, the CAD SIG, to which more than 60,000 households are connected. At the time of its installation, the 800m² plant was expected to have an injected solar production of more than 0.5 GWh per year.

Outperforming original estimations of the system’s efficiency is not the only positive aspect of the pilot project analysis. Monitoring the project allowed TVP to measure the ease of operation of the solar district heating system, which thanks to a fully automated and remotely accessible operation required little human intervention and no cleaning since its installation.

In addition to solar thermal input, the district heating network of Geneva benefits from energy derived from an incineration plant, CHP plants, gas boilers, biomass boilers, and geothermal sources. Thanks to the use of solar heat, approximately 115 tonnes of carbon emissions are saved from the district heating network every year.