The city of Neckarsulm in northern Baden-Württemberg with its 27,000 inhabitants is in the vanguard of solar energy in Germany. It has a cutting-edge position regarding the density of solar thermal and photovoltaic (PV) systems. Within CONCERTO, more than 1,200 m2 of solar thermal collectors and 1.4 MWpeak of PV systems have been additionally installed. 13,000 m² of multi-family houses and public buildings have been retrofitted.
The city of Neckarsulm also constructed 11,000 m² of new buildings during the course of the project and a solar sludge drying plant was completed in September 2009. In June 2007, the high-efficiency retrofit of the Neubergschule, with a gross floor area of 2,862 m2, was finished. Besides retrofitting the building envelope, a new heating system was also installed consisting of two pellet boilers with 69kW each and a prototype Stirling engine. The primary energy demand has been reduced by 75 %.
When taking the electricity produced by the PV system on the school roof and by the Stirling engine into consideration, the primary energy balance comes close to being zero. The school is a fine example that shows the combination of efficiency measures on the building front and the integration of renewable energy sources for energy supply.