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I have an IV measurement program running in LabVIEW, where I measure the IV curve of a photovoltaic module using a programmable electronic load from a quick backward sweep (from Voc to Isc.) I have a really long 10 sq. mm DC wire (ca. 50m) between the modules and electronic load. Below is the IV curve that I am getting. enter image description here

This is not what I desire. Ideally, the current should be zero during the open circuit conditions.

I don't understand the source of this significant current in the open circuit condition.

I have read plenty of literature mentioning the voltages to be not zero during short circuit condiitons and the need for the linear fit, but never read anything for the open circuit conditions. I am looking for possible causes to this, any help/clues would be great.

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  • \$\begingroup\$ Aside from the axis being unlabeled, why do you care about zero current or voltage? Neither represents a particularly useful operating condition and you can always extrapolate if your load is incapable of very low currents or voltages. \$\endgroup\$ Commented Apr 8, 2022 at 12:53
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    \$\begingroup\$ What does your device measure if you connect nothing to it ? I.e. is this an offset of the measurement or an offset of the DUT ? \$\endgroup\$
    – tobalt
    Commented Apr 8, 2022 at 12:57
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    \$\begingroup\$ Label your graph axes. If you put an open circuit on it, the current will be zero. Maybe the electronic load you're using won't go to infinite resistance. Maybe the current measurement device has an offset so reads a finite current even with zero input. And label your graph axes. \$\endgroup\$
    – Neil_UK
    Commented Apr 8, 2022 at 12:57
  • \$\begingroup\$ I don't really understand the point of the chart. How/where is this showing the open circuit conditions? \$\endgroup\$ Commented Apr 8, 2022 at 13:38
  • \$\begingroup\$ Just take one extra voltage measurement from the panel with the load completely disconnected.Job done. \$\endgroup\$
    – user16324
    Commented Apr 8, 2022 at 17:42

2 Answers 2

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The IV curve is what you should see for a photo voltaic module. Here is a standard PV graph. enter image description here. Source: https://www.pveducation.org/pvcdrom/solar-cell-operation/iv-curve

The graph will look like this as long as the PV load is connected. If you disconnect it and have open circuit, you should get a point near 0V 0a or 36V 0A depending on your setup

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The graph looks fine. I suspect either:

  • the sweep started below the true Voc,
  • or the test setup has a minimum load and could not go all the way to open circuit.
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