Demonstration of a 5x5 cm(2) self-tracking solar concentrator

Solar concentration is using optics in order to minimize the amount of expensive photovoltaic cell material needed. For concentration factors higher than approximately 4, tracking the sun's position is needed to keep the focal spot on the solar cell. Based on recent developments using a waveguide slab to concentrate sunlight we propose and demonstrate a light responsive, self-tracking solar concentrator. Using a phase change material acting at the focal spot, it is possible to maintain efficient coupling into the waveguide, up to an angular range of +/- 20 degrees. The system uses the unused infrared part of the solar spectrum as energy for the phase change actuator to achieve its high acceptance angle. With a spectrally matched custom silicon solar cell attached to the waveguide slab, in which light is coupled, the visible part of the solar spectrum can be efficiently converted to electricity. A proof-of-concept single lens device was demonstrated in our previous work. Here we extend the principle to a 3x3 lens array demonstration device. The current demonstration device features an acceptance angle of +/- 16 degrees and an effective concentration factor of up to 20x.