question

kayaktom avatar image
kayaktom asked

One of two controllers is off

Hi, We have two 75/15 Blue Solar charge controllers, each connected to a rigid 175w panel on our pilothouse roof. Both are installed the same way - power from the panel feeds to a 20 amp breaker and then to the controller. From the controller the feed goes to a 25 amp fuse and then to the battery bus to feed the house bank.

Both have worked flawlessly since July, but last week the port controller stopped working. I am getting 26-30 volts coming from each panel at the panel outlet wires, and the same reading at the panel side of the breaker. For the one that is causing trouble, I get 25-30 volts when the breaker is off. If I turn on the breaker, the voltage at the breaker and as read at the charge controller is 12.56 - about .2 volts less than what the battery voltage is showing. The controller state is "off" and no watts are showing.

I have checked all wiring connections, replaced the breaker, replaced the MC4 connectors to the panel wiring and checked the fuse in the controller and between the controller and battery. I'm at a bit of a loss at this point. The other panel is wired exactly the same, and continues to work well.

I can provide the vcsf file for the controller in question.


Thanks in advance for any suggestions! - Tom


MPPT Controllers
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3 Answers
kayaktom avatar image
kayaktom answered ·

Attaching the VCSF file. Anomaly Port.vcsf.zip


anomaly-portvcsf.zip (7.2 KiB)
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klim8skeptic avatar image
klim8skeptic answered ·

I get 25-30 volts when the breaker is off. If I turn on the breaker, the voltage at the breaker and as read at the charge controller is 12.56 - about .2 volts less than what the battery voltage is showing.

@kayaktom This would normally indicate a high resistance connection between the panel and mppt. Or perhaps a faulty solar panel.

Seeing as you have checked the breakers / mc4's and fuse, it might be best to swap the panel that is not producing over to the other mppt. That will narrow down where the problem lies.

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kayaktom avatar image
kayaktom answered ·

@klim8skeptic thanks for the tip. I swapped the panels and the port circuit and controller are now working with the starboard solar panel. But the starboard circuit and controller (that was working previously) is not working with the port panel. So logically it's an issue with the port side solar panel, or with connectors between the panels and where I switched the circuits.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

@kayaktom You can also Test your panel with a multimeter.

Take note of the warnings. This is only for testing one panel at a time. MC4 connectors dont like to be connected / disconnected under load, so cover the panel.

If the panel tests ok, plug it back in. Remove the PV leads at the controller, and repeat the test on the PV cable at the mppt. Again, only test one panel at a time.

If your PV cabling fails that test, connect the 2 PV wires together (short them) and test for voltage across each join, connector, fuse, breaker etc, on the PV cabling. The high resistance joint will have voltage drop across it.

Good luck. Be careful....


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kayaktom avatar image kayaktom klim8skeptic ♦ commented ·
Thanks @klim8skeptic - It looks like it's a panel issue - maybe with the diodes. The amps aren't reading what they should be - I'm in touch with the folks we purchased them from and they suspect an issue with the panel. Your suggestions really helped narrow it down and clarify that it's not a Victron controller issue. For purposes of this community, we can consider it resolved, since it's definitely on the panel side. Thanks again!
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