The two previously described prototypes of concentrating reflectors have been evaluated for incidence angle dependence by indoor and outdoor measurements. During indoor measurements, the collectors where placed at the pivot point of the simulator and the photo diode array was placed on collector surfaces. The irradiance to the collectors where also measured with a pyranometer. The incidence angles were simulated by raising the simulator or by rotating the collectors when placed vertically in front of the simulator.

K(O,0T) was derived from the measured values and divided by fL(0L), in order to get RT(0T). A single outdoor measurement was performed at вт =30° for the roof MaReCo and вт =20° for the solar hybrid window. The relations between the current from the photodiode array and the irradiation at corresponding incidence angles at outdoor measurements were
calculated. A compensation of the cosine dependence of the incidence angles was also performed, assuming that the total irradiation from the simulator is constant throughout the measurement and that the irradiance on the collector is dependent on cos 0T.

The calorimetric measurements were performed with the temperature difference, AT, between the water in the collector and the ambient air maintained close to zero. The flow for the calorimetric measurements is recorded with an inductive flow meter and the temperature difference between in — and outlet is measured with a thermopile consisting of five thermocouple pairs. The thermal performance was registered continuously during the measurements.

A comparison has been made to corresponding outdoor measurements of both fL(0T) and K(O,0t) of the roof MaReCo, that were previously performed on a larger prototype with identical geometrical features.