The first solar autonomous desiccant cooling system in Germany was proofed to be technical feasible. It is important to reduce the system costs by simple solar systems. A desiccant system with solar air collectors and no buffer storage can cope with the comfort needs of buildings used mainly during day time with a high glazing fraction in the facade.

The users of the chamber of commerce in Freiburg, Germany are satisfied with the comfort conditions in the two conditioned rooms. The approach of accepting some hours of exceeding the criteria of the German standard DIN 1946 part 2 to be able to realise a solar autonomous and economically viable system has been proofed positively.

The detailed analysis of measured data pointed out, that in further projects the amount of regeneration energy given by the collector should be controllable. This means to install devices which allow to reduce an exceed supply of collector gains for avoiding unfavourable heat transfer to the inlet air stream. This could be realised by mixing the heated air with ambient air or by using only part of the collector field if necessary.

The COP of the system is strongly depending on the plant design, the operation constellation and the ambient air conditions. Therefore one has to be careful in comparing this system with other systems.

The direction of rotation is influencing the quality of heat transfer. For the cooling case, the wheels should rotate in opposite directions. For the heating case they should rotate in the same direction. This was not known by the installation company. The direction of rotation will be changed before the next cooling season starts and the effect will be evaluated.