LLTHB

OK... my last word on this. For about 25 minutes today I had a situation where there was load shedding, not a lot of PV, battery not completely charged, and (because of the shedding) light loads. For that time span the Goodwe drew about 1.2kW from the panels whilst the load was about 450 - 520 W. So, again, the battery charged and the draw from PV only dropped off when SOC hit 100%.

I'm still on 2525J.

So now I'm as sure as I can be that this problem can be addressed by firmware.

Sad to hear about the service. It seems solar systems have few with REAL great support. Just my uninformed view. 
Your geyser problem is perhaps the easiest to solve. If they are in close proximity a well insulated storage tank and using PV to heat via heat pump. The other option perhaps better is gas geysers as you only use on demand. No point in keeping all hot if not needed every day. 
12 day must be a nightmare. Our longest break has been 36 hrs in 34yrs when a mini sub burnt out. 
 

The helpdesk have confirmed that Goodwe pushed that update through. So despite not selling Goodwe inverters any more, they still have an open channel to them.

Let's hear what @Bobster. can tell us as he knows the Goodwe inverters.