ABSTRACT
The photovoltaic (PV) part of a hybrid PV-thermal (PVT) system depends on the complex temperature behaviour only through the temperature dependence of collector performance, which is weaker than that of the thermal collection part. The heat fluid circuit exchanges heat with a thermal store, from which building loads are covered through a secondary heat circuit. Hourly behaviour of building loads of electricity and heat are considered, as well as heat storage losses depending on temperature stratification, insulation and geometry. The system covers about 5 per cent of the annual electricity load and a similar percentage of overall heat load, but over 50 per cent during summer. The input to the collector is from the lower store and the heat to load is extracted from the upper part, provided it has a temperature higher than the lower one.
