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

Abstract/Summary:

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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.