Solar problem

[Budgie]

Hi guys hope someone can help as pulling my hair out here, I have a 120w solar panel & victron mppt controller that goes through Sargent ec500 on my Autotrail.
All been good for a few years then intermittently getting no solar, have checked the panel on the roof 24v & 4 amps today in sunny conditions here in Cumbria so all seems ok with the panel, connected panel back up and checked the wires from the panel down into van just before i connect to the victron mppt and the same 24v & 4 amps here's the problem as soon as I connect back the the victron the volts go down to 12.5 on the connections this is the same if the victron is connected to the ec500 or not, how come the voltage drop ? The battery is fine only a year old , I have even bought a new Victron as thought it must be that but the readings are exactly the same, it has not charged on solar for 6 weeks I took the van to a local auto electrician and you wouldn't believe when I pulled up at the garage all was fine solar charging great, he checked everything out couldn't find anything wrong and charged me for 30 mins , as soon as i got home I checked the solar and not working again !!!!

 

[Robmac]

Fuse connections all good?

 

[merl]

have checked the panel on the roof 24v & 4 amps

To be honest it sounds like your panel is knackered, No current can flow until the panel is connected to a load so I can't understand how you know that the panel is delivering 4A if it's not connected to the solar controller?
Can you elaborate?
Do you possess a DC clamp meter? If so you need to check the primary and secondary current so firstly the panel current and secondly the current from the controller to the battery, the secondary current will be higher by around 30%.

 

[Fisherman]

Hi guys hope someone can help as pulling my hair out here, I have a 120w solar panel & victron mppt controller that goes through Sargent ec500 on my Autotrail.
All been good for a few years then intermittently getting no solar, have checked the panel on the roof 24v & 4 amps today in sunny conditions here in Cumbria so all seems ok with the panel, connected panel back up and checked the wires from the panel down into van just before i connect to the victron mppt and the same 24v & 4 amps here's the problem as soon as I connect back the the victron the volts go down to 12.5 on the connections this is the same if the victron is connected to the ec500 or not, how come the voltage drop ? The battery is fine only a year old , I have even bought a new Victron as thought it must be that but the readings are exactly the same, it has not charged on solar for 6 weeks I took the van to a local auto electrician and you wouldn't believe when I pulled up at the garage all was fine solar charging great, he checked everything out couldn't find anything wrong and charged me for 30 mins , as soon as i got home I checked the solar and not working again !!!!

From what you report you can rule out the solar panel, the MPPT, and the cabling from the solar.
All that’s left are the battery or a poor connection possibly at the fuse.
I assume you connect the battery first then the solar and not the reverse.
Have you tried taking a reading of the battery at the solar connection cables before connecting to the MPPT.
The fact that it worked fine at the garage then went back into fault mode on return, makes me think of a poor connection between the MPPT and the battery. (Fuse)
It’s also possible that your battery has low insulation, I used to see this with batteries in alarm systems that were only months old.
It’s also possible that you have a problem in your 12v circuit within the van, pulling down the battery.
Good luck.