Dimensioning Method for PVT Collectors as Heat Source of Heat Pumps for Residential Buildings

Photovoltaic-thermal (PVT) collectors are an emerging technology that is increasingly being used as a heat source for heat pump systems in residential buildings. However, a suitable standard methodology for sizing the PVT collectors for these systems is still not available. This paper initially provides a framework for the sizing of a PVT-heat pump system for small houses according to the German guideline VDI 4645. The dimensioning method of VDI 4645 and the sizing method for PVT collectors are incorporated in a web-based tool that is aimed to assist planners (or homeowners) during the preliminary planning of a heat pump system in single and multi-family houses. The methodology also covers the planning of systems with backup/additional heaters (e.g. gas boiler and heating rod), e.g. for buildings with limited roof areas for PVT installations. Different heat pump operation modes, i.e. monovalent, bivalent-alternative, or bivalent-parallel are also considered. A model of the IEA SHC Task44 SFH100, an existing single-family house with radiators, has been chosen as an example case to demonstrate the methodology. For the evaluation of the performance of the designed system, yearly simulations of the system are done in TRNSYS. The results show that the developed methodology provides plausible sizes for the example case. However, further development and validation are necessary to provide flexibility in system dimensioning.