What is the purpose of supplying voltage and current to solar cell during cell measurement?

[sflow]

When a PV is illuminated, it generates voltage and current for measurement. But, why still need to supply load to PV? Can anyone please kindly advise me on this topic as I am doing some research on I-V tester. Thank you.

[Ben]

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@sflow wrote:

When a PV is illuminated, it generates voltage and current for measurement. But, why still need to supply load to PV? Can anyone please kindly advise me on this topic as I am doing some research on I-V tester. Thank you.

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Becuase Ohm said "I=E/R". No path, no "I", :: no "E".

RE:IV curves

[smercurio_fc]

Also, please note that you posted in the forum that discusses the various forums and the forum software. Your question would be better suited to the Instrument Control forum, for example.

[sflow]

Hi Ben,

Thanks.

Best regards,

SF

[sflow]

Hello smercurio,

Noted. Next time I will post to the Instrument control forum.

Best regards,

SF

[F._Schubert]

Ben, nice explanation. But you still can measure Voc -> Sintons Suns-Voc method.

sflow: more precisely you need a controllable 4-quadrant electronic load.

-> 4-quadrant: allows to sink/source current independent of the applied voltage

-> controllable: you want to ramp from Isc to Voc to obtain a curve.

BTW: Check out my companies website (below) if you've got a good deal of money to invest on best quality.

Felix

[Ben]

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@f. Schubert wrote:

Ben, nice explanation. But you still can measure Voc -> Sintons Suns-Voc method.

sflow: more precisely you need a controllable 4-quadrant electronic load.

-> 4-quadrant: allows to sink/source current independent of the applied voltage

-> controllable: you want to ramp from Isc to Voc to obtain a curve.

BTW: Check out my companies website (below) if you've got a good deal of money to invest on best quality.

Felix

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Yes I realized long after posting.

I challenge I faced years ago when I was still a babe to wires and was trying to characterize feroelectric thin film samples. Being feroelectrics they have a hysteresis curve. They widgets were so small that I could not measure the voltage directly even with the best instrumentation amps I could find since even they would load the signal (I actually experimented with using an air gap to get the resistance I was after. No did not work, but I had fun learning how to use a milling machine ). In the end I charged the device with a series capacitor and used the V of the capacitor to figure out how much Q. I suspect my lack of an understanding of how SRs worked lead to that issue I had with integrating the charge (worked on first pass but subsequent attempts bad).

But isn't that what college was for?

Ben

[sflow]

Good day Felix,

Is 4 quadrant electronic load is something related to light forward/reverse test or dark forward/reverse test? Is 4 quadrant electronic load using 4 probing Kelvin method? I have read some articles saying that this probing method is better than 2 probing method.

By the way, some companies offer that their electronic load can source current up to 25A and voltage up to 4V. Can this be too high for a cell?

[F._Schubert]

4 quadrant isn't related to 4 wire technique. It's about sinking the current (negative) your cell produces while applying a positive voltage. You can do this with a pure electronic load (so only sinking operation). But you definitively want to measure a bit further than Isc and Voc (where either current or voltage will switch sign). In addition, 4 quadrant will allow for dark measurements as well (where you need to source currents for positive voltages).

The specific ratings of the supply depends on the type of cells you want to measure. But generally, if you reverse the bias it's possible to destroy you cell with the current of the power supply, while you need that current to measure the Isc.

4-wire Kelvin probing is really necessary with the currents you typically have.

As a general remark, your questions just scratch the surface of problems you will face. But I'm not allowed to provide more details, as the company I work for is making money with this kind of solutions.

Felix

[JackDunaway]

Could we get this thread moved to the LabVIEW or DAQ forum? Thanks!