This article aims to establish a new system for pyranometer calibration traceable to the radiometric chain. Different spectrum high flux LEDs have been used as tunable irradiance sources. The calibration procedure, uncertainty budget, and traceability chain of the solar irradiance measurements are presented. Additionally, the results were evaluated using a reference pyranometer, calibrated traceable to radiometric traceability and World Radiometric Reference (WRR).
The uncertainty values are also estimated to be around 1.19 % (k = 2) for LEDs-based pyranometer-pyranometer calibration (WRR traceability), and about 0.68 % (k = 2) for reference standard radiometer based (Radiometric traceability). The deviation between the reference pyranometer and the pyranometer under test was about 0.8% using LED at 655nm for irradiance of 500 W/m2 .The sensitivity results have been evaluated by reference standard pyranometer traceable to WRR using a xenon lamp as a solar source, with a deviation of about 1 %.