IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration
Subtask A Report, Date:…
3.2 Collector efficiency
Basically the collector efficiency characterise the performances of the solar collector field.
It is calculated as follows:
With:
coll Collector efficiency (-)
Q sol
G
Solar energy collected in the solar loop (kWh)
Solar radiation (kWh)
This performance factor is calculated for a certain period. Usually it is calculated for one day,
or for one month.
Indirectly, the collector efficiency permits also to characterize the overall performances of the
installation. Indeed, if the installation is turned off, because of a technical issue, or because
there is no charge, the energy collected is equals to zero while the solar radiation is still
there. So the collector efficiency value is low.
3.3 Thermal COP
The thermal coefficient of performance (thermal COP) characterizes the internal
performances of the chiller. This performance factor is calculated only in summer (cooling
mode of the installation) as follows:
With:
Thermal COP Thermal coefficient of performance (-)
Q evap
Q gen
Energy taken from the evaporator loop (kWh)
Energy coming from the generator loop (kWh)
Usually adsorption chillers have a thermal COP around 0.4 to 0.5 and absorption chillers
have a thermal COP around 0.6 to 0.7.
3.4 Electrical COP
The electrical coefficient of performance (electrical COP) characterizes the electric
performances of the entire solar installation. This performance factor is calculated all year
long as follows:
With:
Electrical COP Electrical coefficient of performance (-)
Q distrib
E tot
Energy (hot or cold) given to the distribution loop (kWh)
Electrical energy consumed by the solar system (except backups) (kWh)