Optimization of Advanced Building Integrated Photovoltaic and Thermal System with Dual Working Fluid
Abstract
A direct exchange building integrated photovoltaic and thermal (BIPV/T) heat pump system is proposed where the heat extracted from the BIPV is used to drive the heat pump. To ensure a more stable diurnal system performance, especially at low solar conditions, air flow is instituted in the cavity between BIPV façade and the insulated inner wall. The airflow is directed from the heated or cooled space into the air channel and can be exhausted or returned to the space depending on the building operating conditions. The flow and geometrical parameters of the BIPV/T façade are optimized such that more than 40% of the peak performance is recovered by the airflow in the channel off-peak conditions. Also, BIPV façade surface temperature is reduced by up to 10°C compared to air based BIPV/T and the wall heat gain is reduced by up to 46%. A case study scenario is considered where the BIPV/T heat pump system is installed as supplemental heating for an electric water heater and the annual energy saving is quantified. A surrogate model of the BIPV/T heat pump system is developed and implemented in EnergyPlus. The annual energy analysis suggests the Domestic hot water (DHW) heating energy demand was reduced by up to 40.4% for a wall integrated system and 44.2% for a roof integrated system.