Branch connector in parallel setup not doubling amps?

colemab

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I've got the renogy branch connectors and I was doing some testing today on my trina solar panels. They both show 42 volts (yes wired in correct fashion, not backwards) and about 6.2 amps - when testing at the factory wires individually. However, when I hook them up in paralell thru the renogy branch connectors the volts stay the same (as expected) but the amps do too! Why aren't the amps going up by 80-100%? Anyone ever seen this before?
 

Bud Martin

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Can we see the pictures of your setup?
Do you have clamp-on DC Amp meter to check the current on each panel wire of the panels to see what you are getting on each panel of your parallel setup?
 
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Texas-Mark

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However, when I hook them up in paralell thru the renogy branch connectors the volts stay the same (as expected) but the amps do too!

Possible bad branch connector. Try measuring after the branch connector with just one panel, then with just the other. I had a bad one that did exactly what you are seeing. Although mine was bad from corrosion on one input.
 

colemab

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I do have a clamp on meter but in this case I'm using the probes.

I have tried to measure after the branch with just one, just the other one, and with both = get same results.

I also tried swapping out the branch connector for another renogy connector (same model) and have the same problem. That is why I posted here.

I just ordered a BougeRV branch connector set and when they come in (Thursday ETA ATM), I'll re-run the tests and post some photos.

Any idea what causes a branch connector to go 'bad' like this but not fail?
 

Texas-Mark

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Any idea what causes a branch connector to go 'bad' like this but not fail?

A connector not properly mating. But since you said that individually the panels work, I don't know. Did you do the test with both branch connectors? Sure you are totally taking each panel out of the picture?
 

Bud Martin

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So what is the current reading of each panel wire when using clamp-on amp meter, that will tell you what is going on.
You measure it to be 3.1A from each panel?
 

colemab

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Yes, I've tested with both branch connector sets. Made sure the MC4 connections were snug on the cable and into the branch connectors. I guess it is possible both sets of branch connectors are bad. That is why I am trying a different brand name. Nothing against renogy, they've been mostly solid for me.

I totally unplugged the panels when testing - the out panel not being tested was totally disconnected.

I'm down in a valley and the sun has started to set here so I'll have to use the clamp on meter tomorrow (or Thursday) and re-test to let you know.
 

Texas-Mark

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I totally unplugged the panels when testing - the out panel not being tested was totally disconnected.

Just to clarify. Connect one panel only to the branch connectors and test the output of the branch connector. Then remove that panel, and connect the other one, but be sure to use the other input legs of the branch connector.
 

colemab

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Sorry for the bad camera work, hard to hold the probs, meter, and camera without falling.

reading from first / right panel - direct probes no branch
43 volts / 5.68 amps
 

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colemab

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reading from 2nd / left panel - direct probes no branch
43 volts / 5.5 amps
 

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colemab

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reading from BOTH panels from branch connector - direct probes
40 volts / 5.4 amps
 

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colemab

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Left panel clamp reading, 0.11 amps. This is fully connected to the branch connectors and down to the combiner box to the charge controller.

Note the other posts are NOT connected to anything.
 

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colemab

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Right panel clamp reading, 0.07 amps. This is fully connected to the branch connectors and down to the combiner box to the charge controller.

Note the other posts are NOT connected to anything.
 

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colemab

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For the tests, the right panel was on the 'top' part of the branch connector when plugged in and the left one was on the 'bottom' part when plugged in.

Results repeat with replacment branch connector (renogy). Sounds like both connectors are toast. I have new ones coming in tomorrow to test.
 

Texas-Mark

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Note the other posts are NOT connected to anything.

What do you mean by this?

At the combiner box, short the panel leads together and do the clamp readings again. This will give you max current on each panel. There may not be any current flow if the charge controller is not doing anything.
 

colemab

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What do you mean by this?

At the combiner box, short the panel leads together and do the clamp readings again. This will give you max current on each panel. There may not be any current flow if the charge controller is not doing anything.

When using the clamp meters, the system was fully connected / under load to charge the system - yes I confirmed the CC is pulling power in. When using the probes of course this can't be the case as the probes are directly into the panel MC4 connectors or branch connectors.
 

colemab

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The entire system is wired up in parallel if that makes any difference. Also, I flipped the DC breaker in the combiner box off BEFORE disconnecting or reconnecting this string.
 

Texas-Mark

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yes I confirmed the CC is pulling power in.

Do you have more panels than this? Otherwise how do you know?

I still think you need to check each panel (directly) and individually after the branch connector. You may have a bad cable going to the combiner instead of a bad branch connector
 

colemab

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Do you have more panels than this? Otherwise how do you know?

I still think you need to check each panel (directly) and individually after the branch connector. You may have a bad cable going to the combiner instead of a bad branch connector

Yes, there are 12x 400w Trina panels in 6 strings (2 panels per string) down to a aims combiner box. I've checked each panel directly (as seen above in the photos) and after the branch connector individually and together. The readings after the branch connector are virtually the same for a single panel vs both panels. It matters not which ports are being used on the branch connector.

I haven't checked the cable going to combiner yet (but will tomorrow) because the branch connector seems to be the bottle neck.

Thank you for taking the time to look at this crazy thing with me.
 

Texas-Mark

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The readings after the branch connector are virtually the same for a single panel vs both panels. It matters not which ports are being used on the branch connector.

This is the part that does not make any sense. If one of the branch connectors were bad, it should show up when one or the other panel is connected by it's self.

The photos you posted only showed the individual panels (no branch) and then both panels with the branch. The first tests should have been done with the branch, with one panel on one set of branch inputs, and then the other panel by it's self on the other branch inputs. One of those two should have given a faulty reading.
 
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