New technology for precise outdoor PV module performance measurements

Technologies to improve the accuracy of PV outdoor performance measurement are discussed. It is demonstrated that the temporal fluctuation of outdoor irradiance during the I–V measurement, which is a major source of uncertainty in outdoor performance characterization of PV modules, can be reduced to typically < 0.5% by shortening the voltage sweep time to the order of 0.1 – 1 sec. Use of PV devices for monitoring the irradiance is essential for the fast measurements. The present method can significantly improve the reproducibility of the measurements. It is also shown by experiments and FEM simulations that the temperature measurements of PV module are significantly affected by the way of attaching thermocouples and RTD's on the backsheet of PV modules. Good agreement of within 2% compared to indoor precision measurement results is demonstrated based on the present results. A novel performance measurement method is proposed based on the present results.