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Solar Panel IV Curve Tester Recommendations

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trobbins:
Rich, I hope you can manage to use such a commercial IV curve measurement instrument, although now you need to prepare a suitable controlled illumination system with temperature control, which may not be easy.  As this is for pass-fail, the source spectrum does not necessarily need to align with the cells response and could I guess be even LED based.  One preferred method is to use a small encapsulated reference cell and use its output to control the light intensity of the source during testing, and another small reference cell to plot the spatial variation over the plane of the panels during initial setup.  A large LED light source panel may be appropriate, as it should be able to be part of a simple closed loop intensity controlled system, and achieve a short duration test period where temperature change is minimised due to illumination (depending on the test sweep period of the IV curve instrument).  At one time, such PV panel test systems were based on the very short illumination period of a pulse discharge bulb to achieve one-sun illumination.

AJ3G:
Hi trobbins:

This is very good information. I have reviewed some literature on the topic. In the case of the HT Instruments it is being shipped with two accessories, which I think help automate this process. The first is a reference cell for irradiation measurements. The second is a remote irradiation, temperature and tilt angle sensor.

Both of these, from the available literature seem to be highly integrated with the instrument, so they will not provide much use with the SMU should that be the direction we chose. In that case, I think a little more work will be necessary to accomplish the same task.

As I have stated in a previous post, I never had the opportunity to try and measure these parameters before. I am learning a lot about it, and it all seems very interesting. I have used normal TEK Curve Tracers for characterization of components, and despite having this experience never really looked into the SMU’s, or fully appreciated their capabilities.

Rich

trobbins:
At least you have a broad range of products to look at nowadays, although the vast majority are likely aimed at installation verification or maintenance processes for farms (with strings now pushing past 1kVdc).

Absolute simplest pass/fail could be just Voc and Isc, and perhaps a loaded point in the vicinity of Mpp, if you had a room or box etc with a relatively even light source like a light table for inspecting xray films.  If the panels are at the same temp, and the test duration is short (ie. a 3-way switch with 2 DMMs for current and voltage), then repeatability may be reasonable - which you could test by say doing 10 panel samples and then retesting the batch of 10 again a few times - but yes that would be manual entry in to eg. Excel.

I presume the panels would be tested again once installed in end product.

Does the panel OEM provide test certification of any kind?

AJ3G:
Hi trobbins:

The panels would be tested again on the end product. The goal at the moment would be to characterize them here, and save the plots with a serial number. This way we can compare quickly if something has happened while in shipment or during integration onto the satellite. Your idea of a light table seems very doable for me. I have room for something like this.

The OEM provides a IV Curve plot of there own, but I am not sure I would call this an official test certification. From the looks of it, the document they produced is nothing more something to give us a  “warm fuzzy feeling” that their panels are meeting advertised spec. Our whole system is tested after integration to TRL 4 (space qualified).

Rich

floobydust:
The failures I observed were all bad interconnects between cells, and cracked cells was also common. How that shows up on the IV curve is pretty straight forward.
I did not do a hi-pot test to confirm insulation/no shorts to the aluminum frame.

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