Domestic Solar Earth Charging Carbon Zero Hybrid Retrofit

Session 12 Paper 2, CIBSE ASHRAE Technical Symposium, Imperial College, London, UK
18th and 19th April 2012

This paper reports on an experimental augmentation system for ground source heat pumps using solarium style panels to recharge the ground, thermally. The system is running on a house in Nottingham, England. The house has a 4kW photovoltaic array and a ground source heat pump for heating and hot water, using twin 48 metre boreholes. Real-time, Diurnial and Inter-seasonal solar charging restores the energy level in the earth, which prevents progressive frosting of the borehole zone. Measured over a year, it can improve the GSHP performance by a significant percentage – it has been sufficient to reduce the annual electrical consumption for heating and hot water to less than the annual power generated by the PV array on the roof, thus achieving zero carbon emission.