I have an entirely off-grid installation with an existing Phoenix (48V/5000VA) 230V inverter and wish to purchase a MultiPlus (48V/5000VA) 230V inverter/charger to be installed in parallel configuration. The primary goal is redundancy (in case one inverter fails) and to enable charging of the batteries (if needed) from a 3kW generator (continuous 2.5kW capability). A secondary purpose would be to increase the power output capability.
I know there can be compatibility issues that have to be taken into consideration with paralleling.
The original firmware that the Phoenix inverter came with was 2624413. I have updated the Phoenix inverter from v413 to the latest v482 firmware version today, so if the MultiPlus doesn't come with the latest firmware I am more than capable of updating that to the same version.
I would be seriously concerned if a new MultiPlus didn't come with firmware starting with 26 (VE.Bus - new microprocessor, 230VAC) now, but I've cross checked the list of models document and 2624 is listed as "MultiPlus 48/5000/70-100 (+EasySolar)". It is literally the only model on that list that is 70-100 (70-amp battery charging and 100-amp AC transfer capability).
Am I correct in concluding that if I purchase a 2624 (i.e. a MultiPlus 48/5000/70-100) and update the firmware to v482, if needed, then it should be capable of being paralleled with the existing Phoenix inverter?
Second question is, if I was to purchase the MultiPlus and it failed to parallel could I instead fall back on a configuration to feed the AC output from the Phoenix into the AC input of the MultiPlus to increase the output capability?
I already have a changeover switch in the configuration to change the house AC supply from the Phoenix to the generator and could easily reconfigure that output to feed into the AC input of the MultiPlus instead. I'm not sure how the MultiPlus would handle that changeover from the Phoenix to the generator, I suspect it wouldn't too well, and it might get more complicated if the "Dynamic current limiter" setting needed to be enabled for the sake of the generator.
In the worst case scenario, I would feed the Phoenix output into the MultiPlus input and keep the inverters and generator separated by the changeover switch. This would provide the redundancy and increase in power capability. In this case, if I wanted to meet the goal of charging the batteries I would need to purchase a Skylla 48/50 TG Charger, which is practically doubling the cost as it's price isn't much different from the MultiPlus and it'd probably more beneficial to just buy another MultiPlus and just use that purely as a charger (if it can be configured that way). Really don't think I could stretch the budget to handle this.
My preference would be to parallel the Phoenix and feed the generator into the MultiPlus charger, this would eliminate the need for the changeover switch entirely and I think more likely to meet all the goals, but it would also be nice to know that even if I do everything right, there was a fallback position if the paralleling did not go as planned.
Happy to take advice if anyone has a better option to achieve the goals.