Modelling results of covered PVT collectors regarding low-E coatings and F'

Photovoltaic-thermal (PVT) collectors are hybrid collectors which make, in principle, optimal use of the solar resource by co-generating electricity and heat in a single module. The development of innovative PVT concepts is based on a deep understanding of the interplay between design and materials, performance coefficients, and finally the thermal and electrical energy yield. Amongst others, the energy yield is influenced by the low emissivity (Low-E) coating, thermal insulation, and the thermal coupling of absorber and fluid characterized by the collector efficiency factor F'. In this paper, a modelling approach is presented which describes the interplay between optical properties of Low-E coatings, overall heat losses and F'. In analyzing seven different Low-E coatings, the complex interdependence of these three factors becomes clear. A further highlight will be put on the thermal coupling of the fluid to the absorber and its influence on F'. In addition, system simulations for a combi system are carried out to analyze the annual electricity and thermal yields.