Solar assisted cooling systems are installations providing cold for buildings. The energy sources to drive them consist of a mixture of solar energy and an auxiliary energy source (gas, oil, electricity). The solar contribution (solar fraction) for cooling may vary between a few per cent and 100 per cent. In general solar assisted cooling systems or at least the solar collectors can also be used for heating in houses and hot water production. In principle, solar assisted cooling systems may be operated by solar thermal collectors connected to thermal driven cooling devices, solar-to-electric converters (photovoltaics) combined with compression chillers or by solar to mechanic energy converters (e.g., solar collector driven Rankine machines) combined with compression chillers.

Fig. 1: Variety of systems for solar assisted air conditioning

This Annex focuses only on the first category of systems. This type of solar assisted cooling systems consists of four main components: the solar system which may include a heat buffer storage, cooling device, air conditioning system and auxiliary subsystem. The auxiliary subsystem may, in principle, be integrated at different places in the overall system: as an auxiliary heater parallel to the collector or the collector/storage or as an auxiliary cooling device or both.

Fig.2: Solar assisted air conditioning system in Riesa/Germa