II. ABSORPTION COOLING SYSTEMS Solar energy can be converted to both electricity (trough PV cells) and heat (trough thermal collectors) [7]. The absorption phenomenon is the process in which a substance at one state captures one another one at a different state. Absorption chillers belong to the closed-cycle sorption category and are the most frequently adopted in thermal airconditioning applications [8]. The absorption machine can be designed in different configurations as single effect cycle (Fig. 1) and multi-stage cycle.