A Spot-Area Method to Evaluate the Incidence Angle Modifier of Photovoltaic Devices-Part 2: Modules (Differential Method)

In Part 1 of our article, we presented a method to quantify the incidence angle modifier (IAM) of photovoltaic (PV) devices, which differs from the methods proposed in IEC 61853-2 through the following: it utilizes a spot-area irradiation, delivered by an optical fiber system, a customized angle probe holder, and a current-to-voltage converter. Part 1 focused on single-cell devices and presented the validation of the new method on two different cell architectures. In Part 2, we generalize that method to commercial-size silicon PV modules, mirroring by the approach already used for module-level spectral responsivity measurements described in IEC 60904-8:2014. The proposed method is motivated by inclusion in the currently ongoing revision of IEC 61853-2, providing research centers and testing laboratories with an additional option to perform IAM measurements indoors. The reproducibility of the proposed method is addressed in this work via interlaboratory comparison with a different measurement method for the same quantity and with a detailed uncertainty analysis.