Help Troubleshooting no PV Connection - LV5048

[jimjones26]

Hey all. I was tilting my panels today (I made mounts last year that allow me to rotate to proper angle) and forgot to disconnect my main PV breaker before I started. When I came in the PV 1 input was no longer working on the LV5048. I noticed the breaker was on and switched it off and back on. The LV5048 shows the PV connections, clicked on and then clicked back off. The breaker is 50A 150VDC. I switched the breaker off and went outside to test voltage at my combiner box. It was 151V!

At the PV input by my LV5048 right now I am seeing ~80V with the breaker turned off (measuring positive before the breaker and the negative line). When I turn on the breaker, voltage drops to around 50V. I can turn on the breaker and the LV5048 will show PV connection, click on and then click back off after a few seconds. The PV1 display shows ~55V for a few seconds after it clicks on and back off.

Did I blow the breaker? I thought the breaker was supposed to trip? I am at a loss of where to go next. All PV inputs at the combiner box are now measuring around 100V. I am not sure why I was getting a reading of 150V earlier, but I am positive that is the voltage that was coming through every combiner box input, and that measurement lasted for several hours.

Sun flare? Should I rewire my panels to the the VOC down to ~80V from ~100V - ~120V? The LV5048 has a max VOC of ~145V, and now I am feeling nervous. I have been running this setup for 18 months now without a problem, but this is the first time all 18 panels were properly tilted.

Could a ground fault somewhere on the panels be causing the issue? When I tilted one of the wire inputs to the back of a panel got pulled, but I removed the cover and everything looks ok. None of the PV lines seem to be damaged anywhere.

EDIT: The breaker I am using between the PV input and LV5048 says max volts is 125, trip amps are 65. I am guessing the 150 volts damaged something in the breaker.

 

[sunshine_eggo]

EDIT: The breaker I am using between the PV input and LV5048 says max volts is 125, trip amps are 65. I am guessing the 150 volts damaged something in the breaker.

Breakers wear out. You need breakers rated for 150VDC and 1.25X max amps.

You may also have an issue with one or more of the MC4 connectors, etc.

 

[jimjones26]

Breakers wear out. You need breakers rated for 150VDC and 1.25X max amps.

You may also have an issue with one or more of the MC4 connectors, etc.

Thanks for the reply. I am going to unhook all the connections and check each panel with a multi meter. I don't think the breaker wore out, I think something happened when I was messing with the panels, maybe an arc or a connection got pulled loose or maybe even a connection from a panel itself got broken.

I am still confused as to why the voltage was showing 151v, when the max should be ~120v with the way the panels are wired.

A single panel is ~37voc, I have 3 wired to give me ~111voc, LV5048 is rated for max ~145voc. Should I only wire two panels to give me a max ~74voc and more amperage? I want to protect the LV5048.

 

[sunshine_eggo]

111Voc should be plenty fine even for very low temps. Is it possible you got your wiring confused, and you had 4S?

Good plan on checking each panel.

 

[jimjones26]

111Voc should be plenty fine even for very low temps. Is it possible you got your wiring confused, and you had 4S?

Good plan on checking each panel.

No, everything has been working great for over 18 months now in the current config.

 

[jimjones26]

All the PV's seem to be ok. I plugged everything again and checked voltage coming in to the mppt with the breaker off and it is

 

[jimjones26]

 

[sunshine_eggo]

ick

 

[jimjones26]

So the question is, what caused this? It is the positive lead out of the combiner box that connects to the lead that goes into the LV5048. Yesterday, when I was tilting one array, connection got stretched maybe? A sudden burst of solar from tilting the array from October angle to July angle?

 

[jimjones26]

This was the positive line coming from the combiner box to the lines that are connected to the LV5048.

 

[sunshine_eggo]

MC4 are only rated for 30A. How many amps are you feeding into the MPPT?

 

[jimjones26]

That's it. More than 30a. 6 x ~8a. Roughly 48. I have seen the LV5048 registering upwards of 57a. So I need to go straight into the LV5048 from the combiner. So its been a ticking time bomb. When I adjusting 1/3 of my total panels to be at the right angle, the amps probably surged and finished off the connector. I feel stupid and lucky.

 

[sunshine_eggo]

That's it. More than 30a. 6 x ~8a. Roughly 48. I have seen the LV5048 registering upwards of 57a. So I need to go straight into the LV5048 from the combiner.

Good idea. I'd use 6 awg.

So its been a ticking time bomb. When I adjusting 1/3 of my total panels to be at the right angle, the amps probably surged and finished off the connector. I feel stupid and lucky.

Any tension you might have put on it from array realigning might have also compromised the quality of the connection and further increased resistance. Once it gets hot enough to melt/corrode, it accelerates dramatically.

 

[jimjones26]

That was the problem. Replaced the combiner box to inverter wires with 6awg and tested one panel, works. Thanks for your help!