High concentrator photovoltaic systems look for a remarkable reduction of cost in the production of electricity from solar radiation. This is possible thanks to an optical system which focus the light on a small solar cell. In this manner, high cost semiconductor material is substituted by potentially lower cost optical system. Since that, for this kind of solar modules, efficiency of optics system achieves a similar importance than solar cell itself. On the other hand to actually obtain the desired cost reduction, the cost of new elements and process needed must be low.
The purpose of this work is to present the last advances in the industrialization of concentration PV modules based on TIR-R concentrator. To obtain a cost effective solution, the optics system is one of the key elements. Injection moulding technology gives the desired cost and quality requirements for the manufacturing of the optics system elements. The encapsulation process of the whole photovoltaic module for mass production is described. Optimization of encapsulation process of solar cell inside of secondary lens has been carried out. Over that optimized devices several optical efficiency measurements have been done. Individual concentrators have reach 69% optical efficiency. The combination of these concentrators with solar cells of 30-35% efficiency will give high concentration modules in the range of more than 20% electrical efficiency.
Last advances in optical design and manufacturing have helped to enlarge possibilities for optical solutions in any field that used optics elements. However, the useful solution is not always the best theoretical achievable one. Now, to find the right solution, the restrictions usually do not come from theoretical limits of optics, but from the feasibility of its practical implementations. This paper analyzes a set of important figures to be considered in the design of concentration optical system for photovoltaic solar energy applications. To illustrate it, the ISOFOTON optical concentration option will be presented. It is based in an innovative design methods of non-imaging optics and it is called TIR-R:a two stage concentrator with a primary lens, working mainly by total internal reflection, plus a secondary lens, working by refraction.
The Simultaneous Multiple Surface (SMS) method in 3D geometry is presented. Giving two orthotomic input ray bundles and other two orthotomic output ray bundles, the method provides an optical system with two free-form surfaces that deflects the rays of the input bundles into the rays of the corresponding output bundles and vice versa. In nonimaging applications, the method allows controlling the light emitted by an extended light source much better than single free-form surfaces designs, and also enables the optics contour to be shaped without efficiency losses. The method is expected to find also applications in imaging optics