Research and development in the field of absorption machines has traditionally be linked to industrial processes, where it is usual to have residual heat that can be used to feed the absorption machine. That

is one of the reasons of the shortage of low-powered absorption chillers models for domestic applications. Besides, the cheap price of electricity in the last decades, has allowed an incredible technical development of domestic vapour compression systems and the consequent widespread installation.

Today, the increasing price of electricity and the progressive growth of the social awareness about the environmental effects of climate change and its consequences have modified the requirements of the demand, which currently gives priority to the reduction of energy consumption and subsequently promotes the development of smaller machines.

The range of power of the most installed commercial absorption machines for domestic applications covers from 4,5kW to 32kW, stressing an interesting 10kW machine from a Swedish firm. The smallest does not need cooling tower, which is required for the other models to avoid lithium-bromide crystallization.

3.4. Complementary uses

In cooling demand periods, the required solar collector field is going be fully used to feed the absorption machine. Nevertheless, in non-cooling demand periods it could be used to pre-heat sanitary hot water and central heating water. Depending on the surface of the solar field, it is feasible to reach annual savings up to 90% in sanitary hot water and up to 55% in central heating. By this way, the use of the solar field would be continuous during all the year, profiting it 100%, and preventing the collectors from overheating because of water stagnation.