Applying Solar Energy for Cooling - a Basic Thermodynamic Analysis

To use solar energy for driving a cooling process seems to be a promising application of heat transformation processes, in particular under conditions where cooling loads are - at least partly - caused by solar irradiation. For many years significant research and development efforts have been made to develop solar cooling systems that use solar thermal collectors to provide heat as main driving energy for this purpose [1,2]. Mainly heat driven cooling processes using absorption or adsorption refrigeration technology were applied and overall systems were studied and optimized in many pilot and demonstration projects. At the time of carrying out these projects, photovoltaic conversion of solar energy into useful cooling turned out to be less promising regarding economic competitiveness due to the comparatively high cost for the solar generated electricity. As this situation regarding cost aspects has changed significantly it seems worthwhile to compare the two concepts under a new focus. In this paper basic thermodynamic relations are applied for this purpose. In summary, the result of this analysis indicates that using photovoltaic systems for cooling has several significant advantages compared to the use of solar thermal collectors.