Solar controller not receiving voltage from panels

[Dingodave]

Hi there, Just wondering if anyone can help me with a charging problem.
System has been running perfectly until one of my solar controllers stopped receiving a charge.
Controller saying sleep mode(night time) Have tried turning off and on several times including factory reset, but still nothing.
Controller is a 40Amp Epever MPPT tracer. it is connected to 2x 250Watt solar panels in series. I have a breaker between Panel and controller.
When I put a multi meter on the cable before the breaker while breaker is off, I get 44 Volts.
As soon as I turn breaker back on, I get a reading of 12Volts.
This is doing my head in. Could somebody Help Please

 

[Porch]

Sounds like you have a bad connection some place after the breaker. Do the same measurement test (breaker on and off), but measure voltage at each panel.

 

[Bud Martin]

Can you show us the pictures of your wiring/system?
Do you have clamp-on DC Amp meter?
May be you have high resistance in the wiring, connections, circuit breaker, etc.
Example: https://diysolarforum.com/threads/l...n-with-24v-from-bigbattery.29721/#post-357829

 

[Dingodave]

Distance between the breaker and the controller is 250mm.
I'll have to check panel connections next time I'm on the roof.
Seems strange that I'm getting all the power to the breaker then as soon as I connect to controller it goes down to 12 volts.
I did try another controller and it still happened.

 

[Bud Martin]

High resistance in current path will have that symptom.

 

[Dingodave]

Can you show us the pictures of your wiring/system?
Do you have clamp-on DC Amp meter?
May be you have high resistance in the wiring, connections, circuit breaker, etc.

I'll take some pics next time I'm down on the boat. Cheers

 

[Dingodave]

High resistance in current path will have that symptom.

High resistance, meaning wire not big enough?

 

[Bud Martin]

No, it is not because the existing wires are not big enough, the same wires gauge were working, but now it is not working. Poor connection, bad breaker due to poor contact, etc. See my post #3 example in the link.

 

[Dingodave]

No. Poor connection, bad breaker due to poor contact, etc. See my post #3 example in the link.

Thanks Bud, Tried another breaker, did the same thing.
Will check RC4 connections on panels. If ok, will try connecting only one panel at a time.
and see what happens.
I don't want to run new cables if I can help it.
Cheers

 

[brb58]

Like Bud said, you have high resistance between the panels and the breaker/controller.

 

[Vista]

Yes, High resistance issue.

 

[Dingodave]

Had A look at connections. One looked melted so replaced. Checked all other fittings. all good. Tried each panel individually, still no charge at controller.
attached are pics of my 2 x bt50s, PV1 is the array in question. 2x 250 watt panels in series.
PV2 is 1 x 250Watt panel by itself.
I think the next thing I can do is re run new wires and RC4 plugs.

 

[evad]

Can you connect PV2 to the controller that does not work?

 

[Dingodave]

Can you connect PV2 to the controller that does not work?

PV2 is a 20amp controller. Can I connect PV1 Panels that are producing 44Volts to it without damage?
I'll try connecting one at a time.
If that doesn't work, I think running a new cable and connections will be in order?

 

[evad]

You should have a voltage rating for PV2 but what I was suggesting was to connect the pv2 panel to the pv1 controller. That would be only the PV2 panel and its associated wiring. If that works it shows the controller is working. If that is the case remove PV1 from the breaker and connect PV2 there if that works you have proved that the breaker and the wiring to PV1 controller works. Do you have a clamp on DC amp meter ?

 

[Dingodave]

You should have a voltage rating for PV2 but what I was suggesting was to connect the pv2 panel to the pv1 controller. That would be only the PV2 panel and its associated wiring. If that works it shows the controller is working. If that is the case remove PV1 from the breaker and connect PV2 there if that works you have proved that the breaker and the wiring to PV1 controller works. Do you have a clamp on DC amp meter ?

Ok got it. Your suggestion is understood. I have a clamp on but not sure if it works. Will try this arvo.
Worst case, I've got some cable and fittings, so I can run a new line if needed.
Thanks for the guidance. Cheers

 

[Dingodave]

Thank you everybody, have found the problem. After changing pv2 cables to pv1 controller, it seems that the controller was OK. Further investigation, finds another melted rc4 plug. Changed plug and all working as normal again.
Thanks to all your help.
Will be having a cold beer tonight.
Cheers.

 

[Bud Martin]

Glad to hear you found the root cause of the problem. Hopefully your replacement MC4 connectors are better quality.

 

[Hedges]

Were those MC connectors between two panels of same brand?
Or, did it occur where two brands of connector were mixed, like where a cable connected to a panel?

We would like panels to be reliable, and blame problems on a limited number off of-brand accessories where small additional cost could make it reliable.
Suggest you check other mated pairs of similar parentage while under load. Non-contact thermometer could be most convenient.