Reliability investigation for a built ultrahigh concentrator prototype

Abstract

Ultrahigh concentrator photovoltaics hold a great potential in both reducing the cost of photovoltaic energy and to higher conversion efficiencies. The challenges in their design and manufacturing however have not yet permitted a reliable ultrahigh (>2000X) system. Here we propose an ultrahigh concentrator photovoltaic design of 5800X geometrical concentration ratio based on multiple primary Fresnel lenses focusing to one central solar cell. The final stage optic is of a novel design to accept light from four different directions and focus the light towards the solar cell. The extremely high geometrical concentration of 5800X was chosen in anticipation of the losses accompanied with ultrahigh concentration due to alignment difficulties. The system was designed with manufacturability as one of the priorities and resulted in easily achieving >2000X concentration for a first prototype with non-achromatic Fresnel lenses and in house secondarys. Higher concentrations are anticipated for future prototypes but investigation into the cell performance is required. An acceptance angle of 0.4° was achieved for this design which is considered good for such an ultrahigh concentration level and what’s more, even at higher misalignment angles (such as 0.8 or 1 degree) ultrahigh concentration ratios are still achieved in simulations. Such a design could be the breakthrough in concentrator photovoltaic research for reaching higher concentration ratios. The use of flat optics to ease manufacturing and alignment is a simple but effective method to achieve a reliable system that will achieve ultrahigh concentration even at 36% optical efficiency. Such a design will be of use in investigations of concentration, concentrator solar cell development, temperature effects and more; achieving ultrahigh concentration levels not yet tested.