Energy storage needs to account for the intermittence of solar radiation if solar energy is to be used to answer the heat demands of buildings. Energy piles, which embed thermal loops into the pile body, have be. ••A laboratory-scale coupled energy pile-solar collector system was. A gross area of solar collector cw specific heat capacity of water [J/kg/°C]F′. Global warming imposes increasingly more negative impacts on natural and human systems. The urgency to reduce greenhouse gas emissions and limit the global warming b. To understand and quantify the performance of the coupled energy pile-solar collector system for underground solar energy storage, indoor laboratory-scale experiment. 3.1. Maximum inlet temperature of energy pileAs typical examples, Fig. 9 shows variations of inlet temperature, outlet temperature, an.