Thermodynamic Limits of the Use of PCM Simultaneously in Photovoltaic Modules and in Building

Abstract

The paper quantifies the thermodynamic limits on the energy and exergy use that would result from the use of PCM in photovoltaic BIPV modules versus not using PCM, by limiting module temperature to 298 K and the thermal energy use in buildings according to a set of hypotheses. The results obtained have been extended to six different climates. The results show that the maximum use of PCM depends heavily on the climate, therefore in hot climates as Seville, Cairo and Nairobi, the improvements in energy efficiency are very important (multiplied from 6 to 9 times), while in cold climates as London and Helsinki, the improvements are not that significant (multiplied from 1.5 to 2 times). The exergetic efficiency improvements range of about 5% for all climates, due to the low operating temperature of the PCM. These materials requirements are significant, ranging between 31 and 193 kg/m2, with thicknesses between 3.9 and 24.2 cm/m2.