A statistical analysis on market-available solar thermal heat pump systems
During the last years, most various combined solar thermal heat pump systems have entered the market for residential heating and/or domestic hot water generation. In order to determine the suitability of currently developed methods for testing or assessing such systems for present-day solutions, a thorough review and analysis of market-available systems are essential. The basis of the presented analysis is formed by 135 combined solar thermal heat pump systems that were researched and documented from October 2011 till September 2012. They were provided by 88 companies from 11 countries. The characteristics of solar collectors and heat pumps are broken down at the component level. At the system level, the characterisation is centred on the interaction between solar collectors and heat pump. Here, numerous reviewed systems follow concepts using solar thermal energy as a low-temperature energy source for the heat pump, either additionally or exclusively. It is shown by cross analysis that this feature applies especially to systems incorporating unglazed collectors or photovoltaic-thermal collectors. More findings specific to the combination between collectors and heat pump, to climates or countries are presented as well. This research indicates that many solar thermal heat pump systems differ from standard concepts in various ways. The outcome motivates a holistic approach regarding testing and assessing of such systems.