Fig. 1. Overall design plan of irradiance spectroradiometer in reflective solar bands

Fig. 2. Measurement schematic. (a) Full irradiance measurement; (b) diffuse irradiance measurement

Fig. 3. Schematic of irradiance spectroradiometer in reflective solar bands. (a) 3D structure diagram; (b) optical path brief diagram

Fig. 4. Design sketch of front optical system

Fig. 5. Overall schematic of fiber bundle

Fig. 6. Curves of relation between transmission efficiency and length of fiber bundle[19]

Fig. 7. Schematic of VIS module. (a) Optical path diagram; (b) 3D simulation diagram

Fig. 8. Schematic of NIR module. (a) Optical path diagram; (b) 3D simulation diagram

Fig. 9. Schematic of SWIR module. (a) Optical path diagram; (b) 3D simulation diagram

Fig. 10. Light path diagram of four quadrant tracker

Fig. 11. Schematic of parallelogram in measuring institution

Fig. 12. Field observation. (a) Equipment photo; (b) field environment

Fig. 13. Curve of measured full-day solar direct irradiance

Fig. 14. Comparison of cosine curve measured in lab with standard cosine curve

Fig. 15. Measurement results of irradiance. (a) Zenith angle of 60°, a.m.; (b) zenith angle of 40°, a.m.; (c) zenith angle of 40°, p.m.; (d) zenith angle of 60°, p.m.

Fig. 16. Ratio data comparison between irradiance spectroradiometer and SVC in synchronous measurement. (a) Data comparison; (b) deviation