Single Source “solar Thermal” Heat Pump for Residential Heat Supply: Performance with an Array of Unglazed PVT Collectors
Abstract
This work deals with the results of experimental measurements of a novel solar heat pump based heating supply concept for residential heat supply. The constructed load case aims at supplying heat for a single-family house with a moderate heat demand of 45 kWh per m2 and year. An extreme system design case was measured comprising an array of rear insulated uncovered photovoltaic thermal (PVT) collectors, a brine/water heat pump with deactivated resistance heaters and extended temperature range on the evaporator side, and a two-zone combi storage. The main innovation is to operate the PVT array as the sole heat source for the heat pump and accordingly with extended collector loop temperatures below the freezing point. Performance analysis was carried out on two characteristic cold winter test days. Measurement results show that the present system configuration is able to cover the heat demand comprising domestic hot water and space heating. Analysis of the cold winter test days reveal that insignificant icing occurred on the surface of the collectors, and heat demand was met completely. Temperature comfort levels were reached for space heating and with few limitations for domestic hot water delivery. Improper system design was detected, discussed and several concrete optimization potential measures were identified. One was illustrated for a particular night time heat exchange operation on a test day in spring: A significant source temperature increase of 10 K can be expected, if an array of rear non-insulated PVT collectors would be used instead. For a summer test day with electricity data available, component and system performance figures were calculated.