Fig. 1. Plane absorber S-CPC and CPC by cutting off the reflecting surface. (a) Plane absorber S-CPC; (b) CPC by cutting off the reflecting surface

Fig. 2. SCSA-CPC without gap loss

Fig. 3. Flowchart of solution program

Fig. 4. CSSA-CPC models with different dimensions and SCSA-CPC model without gap loss. (a) CSSA-CPC 2; (b) CSSA-CPC 3; (c) CSSA-CPC 4; (d) CSSA-CPC 5; (e) CSSA-CPC 6; (f) SCSA-CPC without gap loss

Fig. 5. Laser experiment and optical simulation. (a) Laser experiment platform; (b) simulation of 15° incidence angle

Fig. 6. Error of experimental value and theoretical value. (a) Incident angle is 0°; (b) incident angle is 5°; (c) incident angle is 15°; (d) incident angle is 25°

Fig. 7. Optical efficiency at different incident angles

Fig. 8. Average optical efficiency and improvement ratio of different CPCs

Fig. 9. Schematic of projection incident angle θ_s for the sun

Fig. 10. Optical efficiency of CSSA-CPC 4 with different concentrator lengths. (a) Average day in vernal equinox; (b) average day in summer solstice; (c) average day in autumn equinox; (d) average day in winter solstice

Fig. 11. Schematic of tilted CSSA-CPC array and optical efficiency of concentrator array with different spacings. (a) Diagram of condenser array; (b) optical efficiency at different spacing