Development Of Next Generation Solar Trackers Based On Shape Memory Alloy To Be Integrated In CPV/PV Hybrid Modules

A solar tracker based on shape memory alloy (SMA) actuators has been developed with the purpose of its future integration within a CPV/PV hybrid module. The use of SMAs allows simplifying the technology of solar trackers, drastically reducing their costs, as well as their environmental impact, while increasing their reliability. To demonstrate the integrated solar tracker (IST) concept, a first functional unit (FU) of CPV module has been developed. It consists of four fixed optical lenses that focus the solar light on four CPV multijunction solar cells installed on a mobile plate that is translated in X and Y direction by SMA actuators. A new closed-loop control system that uses a low-cost LEDs matrix as a feedback sensor completes the FU. Remarkably, the movable plate has been manufactured with a weight of 7 kg to speed up the development efforts towards future commercial modules made up of hundreds of CPV cells. Despite the well-known difficulty to smoothy control SMA actuators, the performed preliminary outdoor tests of the FU successfully showed that in 90% of the experimental cases the absolute misalignment error of the light spot concentrated by the lenses has been less than 0.1 mm, by considering a total stroke of 65 mm. These results are very promising for the development of the new generation of low cost-high concentration, environmentally friendly, CPV/PV hybrid modules with IST.