Reducing uncertainty in PV reference cell calibration


Two different traceability chains are used for the calibration of PV reference cells: i) directly to SI units (via cryogenic radiometers such as the DSR method at PTB) and ii) to the World Radiometric Reference (WRR) such as the DNI method under natural sunlight at JRC. Up to date comparisons of results from both calibration chains and methods using the same reference cell (in particular a filtered reference cell) are sparse.

During a research stay at the Physikalisch Technische Bundesanstalt (PTB), in February and March 2016, a RMG-Researcher from JRC performed DSR reference solar cell calibrations on four reference solar cells (including two filtered reference cells). The measurement uncertainty analysis of the DSR reference cell calibration method was critically assessed and specific experiments were carried out to characterize quantitatively the variability of several components contributing to the overall measurement uncertainty of the final calibration. The results were than compared to the calibration of the same cells with integral methods (done at JRC) and their respective uncertainty budgets. Following this a set-up and measurement procedure at JRC was improved and the corresponding uncertainty budget updated.