Figure 4 gives the PER (Primary Energy Ratio) of the sorption system as a function of the installed capacity of the sorption system (expressed as condenser/absorber power) for four

different houses and without solar system. The PER is the ratio between energy demand (heating, hot water and cooling) and primary energy used, so including electricity used for the system (especially pumps), but not the other electricity consumption in the house (lighting, etc).

We can see that the PER strongly depends on the type of house (and therefore on the space heat demand of the house). At high sorption capacity the PER is higher for houses with a higher heat demand, because the space heat demand forms a bigger part of the total demand. The sorption system is most efficient in (low temperature) space heating. At the minimum energy house the influence of the sorption system is very small.

Figure 5 gives the PER for a sorption system with solar system.

2.20

2.00

1.80 DC

1.60 D.

1.40 1.20 1.00

We can see that the PER can be far higher than without solar system (compare fig. 4). The highest PER is now reached by the minimum energy house. The influence of the sorption system is also far bigger now for the minimum energy house, because solar sorption cooling can now be active in stead of gas driven sorption cooling. For the big house the same solar system (8 m2 collector area and 300 litre of storage capacity) has not so much influence.

Figure 6: Relative contribution of the solar and sorption system (5.5 kW condenser/absorber power) as a function of the installed collector area (300 litre of storage capacity) for the average house.

Figure 7: Solar Fraction for cooling as a function of the condenser/absorber power for four different cooling demands (8 m2 of collector area and 300 litre of storage capacity).

We can see that high solar fractions are possible. A condenser/absorber power of about 4 kW is sufficient (equivalent to an evaporator power of 1.4 kW). For the higher demands the solar fraction also depends upon the installed collector area. For 16 m2 and 11 kW condenser/absorber power the solar fraction is calculated at 75 % at 2.72 GJ/year cooling demand.