camelot-forum.co.uk

Lurker coming back to ask a question on trouble shooting an intermittent issue. I've had my system in place for a year now, zero issues till now. But I've noticed I have a voltage drop in the system.

My panels are 10x Longi LR5-54HIB-405M in series. Hooked up to a Victron 450/200. It used to sit around 340-370 volts so I'm assuming one of the MC4 connectors is either loose or compromised. I've checked the connections within the isolator/breaker/MPPT so I'm fairly certain they are not the culprits. Even busted out the temperature gun.


What should be my first port of call when doing testing on the panels? How to isolate the problem in a sensible manner. Thanks for any input!

Any chance you could plot the current on the same graph ?, either PV current or output current ?

EDIT - And when did this start happening ?, and how often does it happen ?

nowty wrote: ↑Sun Mar 16, 2025 12:50 pm Any chance you could plot the current on the same graph ?, either PV current or output current ?

EDIT - And when did this start happening ?, and how often does it happen ?

I noticed it last week. We've only really had sun for the last few weeks so it's been a while since I've needed to really check on the system solar wise. Just watched it for the last 10 minutes.


I'm waiting for tonight to turn it off for tomorrows hand on approach.

Just looks like normal MPPT algorithm to me, some of the extreme data points might not even be real.

nowty wrote: ↑Sun Mar 16, 2025 1:18 pm Just looks like normal MPPT algorithm to me, some of the extreme data points might not even be real.

You think so? I've just never noticed the massive drops before while being a paranoid observer. But you guys would probably know more than me.

Elkcarcx wrote: ↑Sun Mar 16, 2025 1:21 pm

nowty wrote: ↑Sun Mar 16, 2025 1:18 pm Just looks like normal MPPT algorithm to me, some of the extreme data points might not even be real.

You think so? I've just never noticed the massive drops before while being a paranoid observer. But you guys would probably know more than me.

You really need to see it graphed over an entire day, rather than the live feed over very short time periods.

Have you got the Victron Cerbo and VRM ?, i.e. the data feed back to Victron Remote Monitoring ?

I too wouldn’t assume a problem. Looks like a data anomaly to me…

Other folk on the Victron forum have seen this behaviour, very likely your seeing the MPPT algorithm doing a quick global peak scan for shade management.

https://communityarchive.victronenergy. ... ement.html

The brief voltage transient looks like a normal mppt 'scan' to me too.

If the general mppt voltage has dropped from 340-370 to around 310-330(?) That might suggest you've 'lost' one panel - one panel has shorted bypass diodes perhaps - but that's quite unusual.

Edit: if one of your panels is parially shaded, that could account for the lower voltage.

Thanks for all the replies. I took the Monday before Nightshift to observe and check on a sunny day. I would say that one of my panels is dragging the overall system down somehow. The system was topping out at 1900watts with a far lower voltage than what the past year has indicated.

So I will probably alter my system to two banks of 5 panels to isolate the panel. They are easy to get to, as they are on my fairly flat shed roof. One of the small joys of having the bigger MPPT. I'll keep you guys updated and even show pictures of my struggles.