psmith Posted September 21, 2021 Share Posted September 21, 2021 I am a newbie on this . I was trying to understand few things on detailed computation of mismatch (Loss section that uses RMS of Voc and Isc). As I am seeing the help section , the IV curves are based on single diode model that has following parameters :I = Current supplied by the module [A].- Unknown V = Voltage at the terminals of the module [V].- Unknown IphRef = Photocurrent [A]IoRef = diode inverse saturation current [A]Rs = Series resistance [ohm].Rsh = Shunt resistance [ohm].Gamma= Diode quality factor, theoretically between 1 and 2, often lessq = Charge of the electron = 1.602·E-19 Coulombk = Bolzmann's constant = 1.381 E-23 J/K.Ncs = Number of cells in series.Tc = Effective temperature of the cells [Kelvin]As I understand we get IV curves from this equation .Now looking at the detailed computation, It uses RMS values of Voc and Isc and obtains statistical sample of Voc and Isc . It then uses them in generating IV curves after aligning Voc and Isc (summing etc) . But, As I see the single diode equation has these two parameters as unknown that is calculated from the photocurrent IphRef. I am not able to relate this part . How we are generating the new IV curves from the statistical sample . Are we using this same single diode equation to generate IV curves here or some more info is there? Or I am interpreting things incorrectly ?? Link to comment Share on other sites More sharing options...

André Mermoud Posted February 8, 2022 Share Posted February 8, 2022 The Mismatch between PV modules in an array is a rather rough calculation, based on a statistical distributions of the parameters. The phenomenon is mainly related to the mix of different I/V curves, by calculating the addition of currents (in series) and then voltages (strings in parallel). This is not really sensitive on the exact I/V curve of each PV module, so that we may avoid recalculating the I/V curve from the one-diode model for each module. The shape of each I/V curve will be very similar for all the concerned modules. Therefore this tool uses the basic I/V curve of the reference module, and performs a "scaling" if the voltage and the current according to the individual Voc and Isc of each module. Link to comment Share on other sites More sharing options...

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