I agree with
@sidepod - the vast majority of these faults can be caused by low voltage and when the voltage is shown it tends to be low, but remembering these are all base van features, so this is starter battery voltage dropping, not leisure. Your usage profile (mileage is clearly very low) is also a potential contributor to not having fully charged batteries when it is parked up, doesn’t mean that is the prime cause.
It depends on the setup but the Solar may or may not support the starter battery
It might be that you have an underlying electrical drain on the vehicle that is pulling more power than you can put in, or something is causing a constant wake-up on the vehicle.
If the solar has been added in recently it might be the cause due to incorrect wiring and what it connects into. Equally if it has been fitted for a long time, it is always worth checking the connections haven't come loose or worn insulation. I would absolutely check the earth connection, esp if a factory earth has been removed and an extra connection added with a generic metal ring, check the fixing, make sure none of the wires have been twisted when tightened. If it wasn't a factory earth, then is it a good connection and not just a random fixing.
If the van is still under warranty, then to avoid all doubt, I would take photos of all the solar connections and disconnect them from the van before getting them to review.
Do not clear the error codes before going to dealer, whilst generic diagnostic tools will pull out all the codes and list them, modern dealer tools will do pattern matching, sequence the faults (mileage/time) and look at groups of faults and give a likely cause. This won't be for all faults but common patterns will be.
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