Update PVsyst Help Menu Equation for Shunt Resistance Term in One-diode Model

[kjs55]

Hi,

Someone recently pointed out to me that there's a mismatch between the equation for shunt resistance (Rsh) in the PVsyst help menu linked in Ref. [1] and Eqs. [5]-[6] of the paper in Ref. [2] (incidentally, also Eqs. [6]-[7] of the more recent paper in Ref. [3]; the latter paper incorporates the temperature-(not just irradiance)-dependence of PV module performance into the PVsyst one-diode model). Firstly, Eq. [6] of Ref. [2] is not in the PVsyst Help Docs in Ref. [1] at all. Reportedly (according to Ref. [10] within the paper in Ref. [2]), Eq. [6] in Ref. [2] came from a personal/private communication with the paper's author. Secondly, the term Rsh_base is replaced by Rsh_ref in the PVsyst help documents. It would be good if the PV community can reference the PVsyst help menu in Ref. [1] instead of the papers in Refs. [2]-[3] when it comes to applying the PVsyst one-diode model. For example, the Photovoltaic Performance Modeling Collaborative (PVPMC) community's website (Ref. [4]) and the associated, relevant PVLIB Toolbox function (Refs. [5]-[6]) could then reference the PVsyst Help Docs in Ref. [1] instead of the paper in Ref. [3]. If possible, please advise, and, if necessary, please update the PVsyst help menu in Ref. [1] in order to clarify this point. Thanks.

References:

[1] https://www.pvsyst.com/help/. Then navigate to "Physical models used" > "PV Module - Standard one-diode-model" > "Rshunt exponential behavior vs irradiance".

[2] K. J. Sauer and T. Roessler, “Systematic approaches to ensure correct representation of measured multi-irradiance module performance in PV system energy production forecasting software programs,” IEEE J. Photovoltaics, vol. 3, no. 1, pp. 422-428, Jan. 2013.

[3] K. J. Sauer, T. Roessler, and C. W. Hansen, “Modeling the irradiance and temperature dependence of photovoltaic modules in PVsyst,” IEEE J. Photovoltaics, vol. 5, no. 1, pp. 152-158, Jan. 2015.

[4] https://pvpmc.sandia.gov/modeling-steps/2-dc-module-iv/diode-equivalent-circuit-models/PVsyst-module-model/

[5] https://pvlib-python.readthedocs.io/en/stable/generated/pvlib.pvsystem.calcparams_pvsyst.html

[6] https://pvlib-python.readthedocs.io/en/stable/_modules/pvlib/pvsystem.html#calcparams_pvsyst/

[kjs55]

I watched your recent YouTube tutorial on fitting the PVsyst one-diode model to measurement data (measured I-V curve data as a function of irradiance and temperature) [1] which said something to the effect of optimizing all five (5) PVsyst one-diode model parameters simultaneously won't give good results and so PVsyst doesn't advise this. I'm wondering if you have a citation for that (?). Ref. [3] of my previous post above, which is available to download for free [2] and which builds off the foundational Ref. [2] of the above post, suggests the opposite conclusion in the event, of course, of having well-calibrated data from a reputable laboratory and following the procedures of handling that data as described/prescribed in the paper (self-reference method, deviation in efficiency relative to STC, etc.). At the same time, of course, I'd appreciate a reply to my above post, thanks.

[1] PVsyst 7 _ Series resistance determination, https://www.youtube.com/watch?v=5MJo_9dqbBk/

[2] https://www.osti.gov/pages/biblio/1184501/