Passive solar tracker based in the differential thermal expansion of vertical strips

This paper presents a multiple axis passive solar tracking concept that takes advantage of the thermal expansion induced length variation of a material when exposed to sunshine. The differential expansion of three vertical thin flat strips with different orientations is amplified by a lever system to enable tracking of the apparent motion of the sun in the sky. A passive solar tracking system prototype supporting a photovoltaic (PV) module was built and tested. The model and experimental results show that the tracking system can correctly follow the azimuthal motion during the day. The tracking of solar elevation is less pronounced. The use of this tracking system leads to a 28% increase in PV generation during the testing period.