Fig. 7 shows the convergence of the external quantum efficiency and internal quantum efficiency of the reference solar cell using two systems (a double monochromator and differential SR). Table 3 shows the reference solar cell's uncertainty budgets at a particular wavelength of 600 nm. The results show that the relative expanded uncertainty due to the reference cells' internal quantum and external quantum efficiencies using a double monochromator device converges to the expanded uncertainty using the DSR method. NIS's set-up for Pyranometer Calibration The RKP-575 Pyro-electric is used as a reference pyrometer to calibrate the CMP6 pyranometer. Fig. 8 shows the Kipp & Zonen model CMP6 pyranometer calibration results at different irradiance levels (200 W/m2 and 1000 W/m2 , 800 W/m2 ). The un, certainty budget related to the calibration of the CMP6 has been estimated and reported. Table 4 shows the uncertainty budget of the detector-based calibration of the CMP6 pyranometer at 800 W/m2 . Fig. 7. Comparing the internal quantum and external quantum efficiencies of a reference solar cell using NIS's spectral responsivity facility and DSR system. Table 3 - Uncertainty budget for the measurement external and internal quantum efficiencies of reference cell using DSR method at 600 nm Uncertainty components Solar cell repeatability Reference photodiode detector repeatability Reference photodiode detector calibration Non-linearity of the photodiode detector Adrift of the photodiode detector Resolution of spectrophotometer The reflectance repeatability of a reference solar cell The resolution of optical power meter for cell Instability of the lamp Combined uncertainty (%) (k=1) Expanded uncertainty (%) (k=2) Conclusion This research article presented an example of a low-cost system to measure and test solar cells, photovoltaic devices, and pyranometers. Through the results, this new system proved to be effective and provide accurate results. This research aims to establish alternative methods for measuring and testing solar cells through the hybrid system for measuring the spectral response of photovoltaic cells. The results were compared using the National Institute of Standards (NIS) spectral responsivity system. The measurement of the spectral responsivity and quantum efficiency of reference solar cells using two techniques is converged with each May 2022 Probability distribution Value (%) 1.15×10−8 Normal Normal Normal Rectangular Rectangular Rectangular Normal Rectangular Normal 3.12×10−8 0.5 5×10−6 1.036×10−3 4.81×10−5 7.37×10−2 2.78×10−4 3.27×10−2 0.51 1.01 Fig. 8. The sensitivity of the CMP6 pyranometer at different irradiance levels; the error bars present the uncertainty values. IEEE Instrumentation & Measurement Magazine 27