The effect of using secondary optical element in point focus fresnel lens based CPV system

In this study, the performances of CPV systems with double optical elements using point focus Fresnel lenses were analyzed under different solar radiation intensities (G=500 and 1000 W/m^2) experimentally. In this context, the effects of primary and secondary optical elements' concentration ratios (C_1, C_2), f numbers (f_1, f_2) and distance between lenses (L_D) on CPV system performance were investigated in detail by considering several 33 CPV system configurations with single and double optical elements consisting of different Fresnel lens couples which have particular optical specifications. Accordingly, using of secondary Fresnel lenses which have convenient optical specifications enhanced CPV system performances significantly. In general, till distance between lenses reaches to a certain value, CPV system performance is getting better with the rise of L_D but when coming up the L_D critical value, system performance is starting to get worse. This critical distance of L_D decreases with the rise of C_2 (f_2) by pegging f_2 (C_2). Besides, CPV systems with double Fresnel lens applications which have low f_1 values are considered to get power close to systems with simple Fresnel lenses. And also, if the performance of CPV systems are desired to enhance by using a secondary Fresnel lens, it is resulted that f_1 value must be bigger than 0,5 for primary optical element. In conclusion, for the purpose of predicting the effect ratios of optical elements belonging to Fresnel lens couples on CPV system performance, statistical analyses were attained via ANOVA method by using the datas as a result of the experimental studies. It is determined that C_1 ve f_1 as primary optical element specifications are mainly effective on CPV system performance with the application of double Fresnel lens, additionally f_2 of secondary optical element's f number is the optical parameter which has the lowest effect on system performance.