Energy potential of a Massive Solar-Thermal Collector design in European climates

• A numerical design model of a Concrete Solar Collector (CSC) has been developed.
• Transient simulations for three European climates have been carried out.
• For Stuttgart climate, the CSC reached a winter energy yield of 460.77 kW h/m2/y.
• CSCs can be alternatives to air-source compression heat pumps.
• Morris method has been applied for ranking the most influent design parameters.

The aim of this work is to investigate the energy potential of using exposed concrete structures as solar energy absorbers (here denoted with the general term of Massive Solar-Thermal Collectors, MSTCs) during the heating period and in particular the design of a Concrete Solar Collector (CSC) is then presented. The CSC is a particular kind of MSTC, conceived as an exposed free standing structure that embeds a coiled pipe heat exchanger in a massive-concrete matrix. A numerical design model has been developed and parametric simulations have been conducted in order to get a figure of the energy potential of the CSC under different European climate conditions. The CSC has reached an energy yield of 460.77 kW h/m2/y and an average heat flux of 93.07 W/m2 for the reference climate of Stuttgart (Germany) during the winter season (inlet fluid temperature of −5 °C and mass-flow rate of 45 kg/h/m2). The Elementary Effect Method has been adopted as Sensitivity Analysis procedure with the aim of understanding the dependency of design parameters on the energy output. Finally, an economic analysis has been carried out by comparing investment costs and energy outputs.