Energy and economic performance of solar-assisted cooling systems for Southern Italy: a critical comparison based on a case study

The growing availability of low-cost electricity-driven air-conditioning systems has determined a huge increase in the electricity demand for space cooling, especially in warm and hot climates. In this framework, solar-assisted cooling systems are a very interesting alternative, since they are mainly fed by thermal or electric energy produced by converting the largely available solar radiation: however, their economic convenience is still questionable. For this reason, many EU states have introduced suitable subsiding schemes: in Italy, for instance, the so-called “Conto Termico” has introduced cash-back incentives proportional to the thermal energy delivered by solar-assisted thermal systems. This study presents a case study including a solar-assisted cooling system for an office building located in Palermo (Southern Italy). After a preliminary assessment of the cooling needs and the peak cooling load of the building, a simplified sizing of the system is carried out. Then its technical-economic feasibility is assessed taking into account the incentives introduced by the Italian “Conto Termico”. The results highlight that the proposed solar-assisted cooling system can significantly reduce primary energy demand and CO2 emissions if compared to a conventional electric cooling system. However, even under these benefits, investment costs are high, as proved by the relatively long payback periods. Furthermore, the incentives call for high collecting surfaces, which is not always a rational choice.