It works perfectly ok in either isolated role.
The give priority to
Solar setting is there to stop the thing going into a hysterical loop when using a a chassis
battery trickle charger like the Sterling BM12123.
Without using that setting when the chassis
battery rises above the B2B cut in threshold the charger can switch over to B2B mode until the voltage drops below the threshold, this counter productive hence the setting.
It's a shame the Ring isn't a bit more intelligent it also a shame there is not a remote display for it either as its still a pretty good value bit of kit with a very unique feature, very few combined Mppt/B2B units support more than around 25-30Voc the ring supports 50Voc and that the primary reason I bought mine it allows virtually every size panel on the market to be used.
@Londonboii
The Ring is rated at 30A output, that max current is only ever drawn when a
battery is heavily discharged and even then during a relatively very short period of time during the bulk charge phase.
Which for a typical 12v lead acid
battery peaks at around 14-14.6V hence the ring can support around 440W of
solar to achieve that output.
In reality
Solar charger rarely reaches max current I would be almost inclined to say never!
A 440W array flat on a roof will never produce 440W
Even if it could on a bright sunny day in midsummer a heavily discharged
battery bank will have probably completed the highest current part of the bulk charge long before mid day.
Hence imho you could probably hang 600-1000W off the thing via say a 25-30A
fuse on the PV input (just to be safe) and it would work perfectly ok and well within it capabilities.
In fact this technique works extremely well late summer through to early spring where PV is not particularly good but is the time of year when we need every bit we can get.
The exception to the above suggestion is if you do something like run a 2kw kettle via an
inverter midday with the sun directly overhead.
Then that massive hit on the batteries might knock the voltage down to the point the controller will switch to bulk charge and could either pop the PV input
fuse or show error E3 but in all honesty at that time of year your typical single 300W panel is usually more than enough.