Design And Optical Properties Of High - Power Spot Fresnel Lens

By overcoming the weak point of low solar energy density, CPV(concentratorphotovoltaic) has obvious potential for depressing electricity-generation cost,enhancing out-power, and putting forword PV application in scale as well. There,Fresnel lens should be the most important accessory,which would seriously producean effect on out-power of CPV.Based on the geometrical optics principles, the influencing factors of the Fresnellens optical efficiency was analyzed. Firstly, using AutoCAD modeling software andTracepro optical simulation software, the irradiance distribution on the focal plane oftraditional Fresnel lens was analyzed, that was focus on the non-uniformity of theirradiance distribution. Then in view of the light intensity superposition principle, twoimproved design of Fresnel lens were proposed, which were modularity multi focustype Fresnel lens(MMF) and ring surface focusing type Fresnel lens(RSF).Adopting software of AntoCAD and Tracepro, the above two types Fresnel lenswere investigated, and the irradiance distribution of these lenses was simulatedfurther by ray-tracing. The results were following:(1)The MMF Fresnel lens could bring about energy re-distribution on focal point,which could result in uniform irradiance.(2)The RSF Fresnel lens should be design for fabrication in practice. In ourwork, for a sample of250mm×250mm size,1mm ring space,10mm×10mm acceptarea,625geometry concentrating ratio, the desired result could be developed. Theenergy peak value was2.9292×107W/m2, the energy average value was3.666×106W/m2, and the ratio of them was7.9.(3)A comparison of multiple ring surfaces showed increasing the quantities ofring surface would improve the uniform of irradiance distribution.(4)Due to the similar structure with traditional Fresnel lens of single focal point,the RSF Fresnel lens should be suit for fabrication and application.