Solar panel testing

[Bud Martin]

I set the multi meter to dc amps red probe to the red wire in the connector and black probe to the black wire of the connector

Well, that is why your reading is wrong, if you look at the meter probe terminals, you will use red and black probe wire when you try to measure current in uA only, otherwise you use clamp for higher current readings.
Please read the meter manual, and I hope you did not damage the meter and hopefully the meter fuse should have blown when trying to use the probe wires measuring high current in Amp range to protect itself, the probes are for up to 200uA measurement only.
See:
Page #10 for high current reading.
Page #14 for low current measurement. See warning: DO NOT attempt to measure more than 200uA!

https://data.kleintools.com/sites/all/product_assets/documents/instructions/klein/CL390-1390366ART-WEB.pdf

 

[RCinFLA]

I set the multi meter to dc amps red probe to the red wire in the connector and black probe to the black wire of the connector

Your first picture of meter does both AC and DC via clamp on. I think you have to press orange button with selector on 40A to measure DC current via the clamp on jaws.

Don't use 400 A scale for 5 amps, it will not be accurate. Use the 40 amp scale which is lowest clamp on amperage scale. For DC clamp on measurement you usually have to press the Zero button to zero out display current first.

 

[Bud Martin]

OP: Guide to Troubleshooting Solar Panels, Voc/Isc Measurements and Most Common Solar Panel Issues!
Notes: I cover the panels with card board/blanket first before shorting the MC4 together then remove the card board/blanket to read the result and then cover the panels again before disconnecting the MC4 connectors otherwise you can have good spark.

 

[RV Jim]

After watching the video I think I will disconnect all the panels and test each individually and if everything is close to one another I will continue with the project if not I will be back here for more AWESOME ADVICE...

 

[RV Jim]

The sun is setting and everyone has giving me great advice and lots of things to look at and test. The person I purchased the trailer from used a power station ..either a Bluetti or an ecoflow...I'm thinking I can do better and custom build a system that would be best for our needs and be able to add what is needed in the future or redesign it if necessary.

 

[Bud Martin]

After watching the video I think I will disconnect all the panels and test each individually and if everything is close to one another I will continue with the project if not I will be back here for more AWESOME ADVICE...

It is great to do hands on learning, never stop learning is my motto. I also learn so much from Will and this forum, the knowledge I get did not cost me anything, thanks to Will and many members here.

 

[Bud Martin]

Bud confused me putting a picture of an AC only clamp on meter.

Your first picture of meter does both AC and DC via clamp on. I think you have to press orange button with selector on 40A to measure DC current via the clamp on jaws.

Don't use 400 A scale for 5 amps, it will not be accurate. Use the 40 amp scale which is lowest clamp on amperage scale.

The picture is B&W so it is hard to see the dash and the solid line on the meter

 

[RCinFLA]

The picture is B&W so it is hard to see the dash and the solid line on the meter

I see that now after zooming in on picture. Sorry.

The panel in the video is very appropriate as panel used has same 36 cell configuration as the flexible panel so Voc should be similar.
Only thing I would recommend is turn the panel over or throw a cloth over it when shorting out the MC-4 connection. No need to make and break the contacts with 5 amps flowing through the connection as it may pit the contacts slightly from the current arc. Worse when dealing with higher voltage of panels in series.

 

[RV Jim]

Sorry if I wake any of you up this early on a Sunday BUT before I take any of the connections apart I have a couple of questions. It appears that the right 2 panels are connected together and the left 2 panels are connected together. Meaning that the positive on 1 right side panel is connected to the negative of the other right side of the panel. Is that the normal way of connecting them ? It ends up basically with 2 50 watt panels that are connected to a Y that in turn is connected to 1 red and 1 black cable going into the inside of the trailer.

 

[RV Jim]

More numbers for y'all to digest. The panels are grouped in pairs and I tested each panel separately and I will list each.
Right front 2.0 amps, right rear 2.7 amps, left front 2.8 amps, left rear 1.8...left rear is beginning to delaminate/wrinkle. The right side I washed and the left I did nothing to it. I await advice and or comments as to the readings.

 

[RCinFLA]

More numbers for y'all to digest. The panels are grouped in pairs and I tested each panel separately and I will list each.
Right front 2.0 amps, right rear 2.7 amps, left front 2.8 amps, left rear 1.8...left rear is beginning to delaminate/wrinkle. The right side I washed and the left I did nothing to it. I await advice and or comments as to the readings.

What was their Voc's.

 

[RV Jim]

Oops I knew there was something I missed...I will have those numbers in 10 minutes....

 

[chrisski]

More numbers for y'all to digest. The panels are grouped in pairs and I tested each panel separately and I will list each.
Right front 2.0 amps, right rear 2.7 amps, left front 2.8 amps, left rear 1.8...left rear is beginning to delaminate/wrinkle. The right side I washed and the left I did nothing to it. I await advice and or comments as to the readings.

IME if those readings were taken at the same time and the panels were at the same angle, it does point to something being off. If the diodes are bad it would be interesting. Bad diodes on panels are the only thing we can fix on a solar panel to make it better, but the only post I've seen where a diode fixed anything is when I prior owner for some reason had physically cut a diode out of the junction box for some reason. So, odds are the panels are simply not producing the same power.

Honestly though, these are used panels and if you have any way to hook a solar charge controller, a battery, and a load you can get data to see if these panels that produce say 200 watts that in their early days produced 400 watts, will these meet your needs for now.

The 36.4 volts you have now is fine to charge a 12 volt and probably 24 volt battery through an SCC.

I'm not sure how the panels are mounted to the roof, so to me its a choice of whether to figure how to scrap the old ones or get new ones that most likely are not unscrew and replace and will require mounting.

 

[RV Jim]

Ok the pictures I am posting are in order right front, right rear, left front, left rear..not sure if it makes a difference

 

[RV Jim]

I think I have resigned myself to getting new panels. Now for the $64,000 question. I am leaning towards 2 200 watt panels so I would have room for 2 more if need be on the roof. What panels would you suggest? This is a twofer for my $64,000 ...my plan for mounting would be unistrut the 13/16th x 1.625 the length of the trailer and the 1.625 x 1.625 across the trailer for better panel support.

 

[RCinFLA]

Assume your Voc numbers are open circuit with no load on panels. Panels appear to have severe leakage current. This is typical failure mode for flexible panels.

If a bypass diode was shorted, Voc would be low, but Isc should be correct assuming full sunlight. If sun illumination was low, Isc would be low, but Voc would be correct.

In your case neither Voc or Isc are correct. Panels are internally bleeding their illumination current.

 

[chrisski]

I think I have resigned myself to getting new panels. Now for the $64,000 question. I am leaning towards 2 200 watt panels so I would have room for 2 more if need be on the roof. What panels would you suggest? This is a twofer for my $64,000 ...my plan for mounting would be unistrut the 13/16th x 1.625 the length of the trailer and the 1.625 x 1.625 across the trailer for better panel support.

I consider panels a commodity. Really goes by measurements: length X width. Sometimes 100 watt panels will fit the jigsaw better. Some panels are more efficient than others, but may not be and with the extra cost you may not be able to fit any more on the roof.

If the roof can support it, I recommend flat panels which will last the life of the trailer, or if not can be replaced by flexible panels which may get you in the same boat with replacing them a couple years down the road.

 

[RV Jim]

Does anyone have a "go to flat panel or a stay away from these panel" I really only want to this once..maybe twice...I'm 69 and REALLY don't want to do it more than twice.

 

[RCinFLA]

Clear plastics do not stand up to UV sunlight. UV breaks up the polymer chains. A couple of years of exposure is about the lifetime if permanently exposed to direct sunlight. Think of head light lens.

You can make them last longer if you take them down and put them away when not using them but the more you handle them the greater the risk of over flexing damage. If you place a cover over your RV that would also help.

If you must have flexible panels it is best to go into the endeavor with the expectation you will be replacing them every couple of years.

 

[RV Jim]

I am an absolute beginner at solar and all it encompasses which is more than I have anticipated it was going to be. I'm not afraid of a challenge or the work that comes it. Just looking for good sound advice from someone who has been there and learned and has real life experience to share.