Evaluation of CPC-collector designs for stand-alone, roof- or wall installation

An asymmetrically truncated non-tracking compound parabolic concentrator type collector design concept has been developed. The collector type has a bi-facial absorber and is optimised for northern latitudes. The concept is based on a general reflector form that is truncated to fit different installation conditions. In this paper collectors for stand-alone, roof and wall mounting are studied. Prototypes of six different collectors have been built and outdoor tested. The evaluation gave high annual energy outputs for a roof mounted collector, 925 MJ/m², and a stand-alone collector with Teflon, 781 MJ/m², at an operating temperature of T_op = 75 °C. A special design for roofs facing east or west was also investigated and gave an annual energy output of 349 (east) and 436 (west) MJ/m² at T_op = 75 °C. If a high solar fraction over the year is the objective, a load adapted collector with a high output during spring/fall and a low output during summer can be used. Such a collector had an output of 490 MJ/m² at T_op = 75 °C. Finally a concentrating collector for wall mounting was evaluated with an estimated annual output of 194 MJ/m² at T_op = 75 °C. The concentrator design concept can also be used for concentrators for PV-modules.