Temperature coefficient measurements of PV modules and uncertainty analysis

Temperature coefficient (TC) measurements of PV devices are required for energy yield estimations. However, a large deviation in measurement results is still being reported. This paper outlines the measurement setup at CREST, the sources of uncertainty and their estimation and methods for propagating them to the final uncertainty of the TC. While for very small uncertainties Ordinary Least Squares (OLS) linear regression may be appropriate for realistic uncertainties a Weighted Total Least Squares (WTLS) is recommended