Uncertainty Evaluation of Primary Reference Photovoltaic Cell Calibration Under Outdoor Condition in Tibet

A primary reference cell calibration testbed using direct normal irradiance calibration method is developed to establish calibration traceability chain of PV scale by Institute of Electrical Engineering (IEECAS) and New Energy Research and Demonstration Centre (NERDC) of Tibet. The testbed is designed to carry out PV reference cell primary calibration under direct irradiance condition, which meets the requirement of IEC 60904–4. The calibration value and uncertainty analysis of direct normal irradiance, spectral mismatch correction, and short-circuit current measurement are discussed and evaluated for photovoltaic metrology calibration reference. The calibration method is based on absolute cavity radiometer which is calibrated against world radiation scale. The calibration result shows expanded uncertainty of 0.91% and desired results reproducibility for establishing on-site photovoltaic metrology traceability chain in China.