A micro photovoltaic-heat pump system for house heating by radiant floor: Some experimental results

A theoretical-experimental research has been carried out feeding a reversible air-water heat pump, 6 kW heating capacity, through a solar photovoltaic (PV) micro grid. The heat pump heated a laboratory which is used as a prototype for the study of solar heating systems. The PV field consists of 16 modules with an useful an total area of 18.7 and 21 m², respectively. Each module, composed by 48 polycrystalline silicon cells of 0.02434 m⁴, has a nominal efficiency of 14% and peak power of 180 W. The PV system stores electricity in 250Ah batteries from where is converted from DC to AC through a 3.0 kW inverter which feeds the heat pump. It works supplying 840 l/h of hot water at 35-45°C to the radiant floor. The data measuring system is recording variables such as solar radiation; temperatures; input power to batteries; heat produced by the heat pump and transferred by the radiant floor; heat pump's COP; solar fraction, etc. The objective of this work is to present and discuss the experimental results obtained during the period 10^th-17^th of February, 2013, including the detailed results of a representative day, 15/02/2013, using only PV source electricity.