Hi,
I went away for 6 months and came back to my van, made a firmware update and the solar doesn’t work any longer. It may be the update. There has been another update which I applied recently.
Could there be a setting which was changed in an update?
I have checked all the connections are in. 15.35V comes from the full French sun right now. 13.75V on the battery side. But the battery is not being charged.
I don’t understand what ahs changed, it was fine last year.
Some things of note when looking at your system.
The mppt is charging your battery. The PV voltage is a bit low, is it particularly hot? Are you using a 36 cell panel with a Vmp of 18V plus?
There is a voltage drop of 0.25v between the mppt and battery, loose connections?
You are using the wrong type of cables to connect the mppt. Refer the manual.
Could you possibly make the connection to the mppt look a bit more tidy. (I’m being nice here)
Is the battery fused?
Thanks I know it’s not pretty, not any shop I’ve visited, I haven’t seen better materials than I have.
The connections are in, one checked that.
I’m confused because it was fine for 5 years, then just stopped.
I wonder about settings changing without my knowledge. I’ll check the manual again.
Settings can’t just change, with age connections wear or get loose, systems prone to vibration, like vehicles, are more at risk, especially with connections like that which really need to be neatened up. Typically it is something like that. Updates don’t happen accidentally, they must be loaded and settings on chargers are preserved - unlike the vebus inverters.
I have checked that things are secure. Yes it would be desirable to change the cabling, but I can’t just do that.
I guess this all looks okay?
It’s too hot to work in the van now. I’ll have a go at reworking the current wires after the weekend and get back here with the results.
Thank you all so far.
In response, yes today is 35 degrees. The van is open, but I can’t get it cooler.
I can’t remember what the panels are any longer. It’s been so long since I bought them and set it all up.
Do have a good look at your panel.
Count the number of cells.
Big bird poops, or thick dust will reduce the current the panel can produce.
Flexible panels are somewhat prone to failure. Reducing output.
Hi people.
I have things open. I’ve checked the mppt connections are solid and they are.
The battery has 13.7v
The mppt is inputting 15-20v
The mppt is outputting 14-15v
The day is cool, there was a huge storm last night.
The battery is not charging with the voltage going into it. Why might this be?
The battery charges when driving via the alternator.
The battery charges when charged by the victron blue smart charger great.
Why is solar not topping things up? Even when the mppt sends out what I assume is enough voltage?
When using the van power is cut, fridge and lights up, it charged the battery, but not while the fridge, etc are on. In the past the solar could charge the battery even when the van was left in 35 degree heat with the fridge on.
I’m going to clean the panels.
I have measured them at 118.5x54 cm which fits the Renogy 100w flexible panel, and that sounds familiar in my mind, but it has been 8 years since I installed them.
I have cleaned them, and they are still only outputting 29w, midday in South France, on a just about cloudless day, barely noticeable haze.
this leaves the battery discharging in this state.
I will visit a shop and ask about better fitting wiring in the coming days.
What am I missing in troubleshooting the system.
Many thanks 
Then you write
You have a bad connection / fuse / beaker between the mppt and battery. Have you checked the fuse in the bottom of the mppt?
What should the voltage be at the battery connection? I can see that when I disconnect the solar from the battery that the solar outputs 15ish V. It is sending a little power to the battery, just not much. The power from the solar is making it to the battery positive terminal, but it is very weak.
Voltage at the mppt’s battery connection should be the same as the battery voltage, 13.7v.
Even when not connected to the battery?
It does go to the battery’s voltage when connected to the battery.
Looking at your panels, they are wired in series. the PV voltage should be about 36v.
PV voltage falling to near battery voltage is an indication of a bad connection between the array and mppt. Or perhaps a faulty panel.
Thanks for that.
For the rear panel, I can’t seem to work my multimeter for AMPs, but it’s giving 20V. With me shading it and without. When I remove the front panel from the system, it is sending 30+W to the MPPT.
For the front panel I get no voltage. I guess it’s broken, and again now AMPs.
It’s kind of warm now, 29 degrees, is 32W reasonable for an 8 year old panel that would have been 100W new?
You need to brush up on your multimeter skills.
The black lead stays in the COM terminal for both voltage and current measurements.
That said, check the panels again.
The other thing to note is that any shade will reduce array output. The panel between the roof racks will always have some shade reducing it’s output.
