Precise measurement of solar cell performance in production

The economical relevance of a shift of several percent in the produced output of a PV factory is obvious. Basic for the assessment of cell performance in the cell sorter measurements at the end of a production line are calibrated references. We report on the leading-edge achievements of a cooperation project between most relevant German cell and test equipment manufacturers with Fraunhofer ISE CalLab PV Cells and the PTB in this research field. A significant reduction in the uncertainty of the calibration of large area industrial cells without cell inter-connectors has been achieved. Uncertainty in the short circuit current was reduced from previously 2.5 % to now 1.8 %. A series of measures to assure long term comparability of calibration results was established. Criteria for the selection of reference cells were agreed upon. Optical features of industrial cell testers were assessed on the basis of a complete uncertainty calculation for the attribution to a simulator class. Some progress steps in the complex metrology of a light sensitive device are exemplified in the paper.