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Very Accurate Outdoor Estimation of Voc’s Temperature Coefficient from Equivalent Cell Temperature Sensitivity Analysis?
G.H. Yordanov, S. Herthogs
Temperature Coefficient, Outdoor Testing, PV Module, Modelling, Equivalent Cell Temperature
Photovoltaic Modules and BoS Components
Subtopic: PV Module Performance – Modelling, Testing, Standards
Event: 8th World Conference on Photovoltaic Energy Conversion
Session: 3BV.3.19
674 - 677
ISBN: 3-936338-86-8
Paper DOI: 10.4229/WCPEC-82022-3BV.3.19
0,00 EUR
Document(s): paper, poster


We explore a novel method to potentially very accurately estimate the temperature coefficient (TC) of ß a PV module’s Open-circuit voltage VOC in outdoor characterization. The goal is to improve the accuracy of the classical methods for outdoor evaluation which can have significant uncertainties, causing a less accurate Equivalent Cell Temperature (ECT) evaluation. The ‘RMSE method’ is based on sensitivity analysis of ECT with respect to the error in the used ß value. The difference between the calculated ECT and measured Tback is plotted over the effective in-plane irradiance, resulting in a AT scatter plot. Our decomposition of AT(ß’) very accurately describes how the AT plot changes with an erroneous value ß’. We refute the initial hypothesis, namely, the ß’=ßR corresponding to minimal scatter is not the true ß (but for most c-Si PV, ßR and the classic value ßo differ within a few %). Our accurate RMSE fitting for c-Si and thin-film PV suggests correct mathematical modeling but the corresponding scatter term in the decomposition is independent on the true ß. The ‘linear’ and ‘vertical-axis intercept’ terms can be investigated in future works. The ECT evaluation procedure has also been adapted to bifacial (BiFi) c-Si PV modules in earlier works, and therefore the present line of research is also applicable to that technology.