The inverter itself is only designed to output 120v. I don't think any RV'ers have any 240V appliances, maybe somewhere out there (never say never) but it's just not needed or common, and would be something custom someone did on their own.three A/C units! Ok now makes sense. Would probably not need this for a van build then.
I understand the part about the 4 wires, the receptacle has L1, L2, N, and PE/gnd. Theoretically, you could run US 240v appliance off this if your rv had it. I was wondering if any RVs actually had them.
Next question: why don't RVers just install more solar and a bigger inverter then? Solar panels are cheap nowadays and you have the roof space. Difference between 3kw and 5kw is only ~$300 (edit: more like $700, still) and a ~13kWh batt is like ~$2000 with reputable Eve cells. I think @cinergi has such a system. Then you don't need to be tied to a plug and it should pay itself within a year or two?
Until a few months ago, for Victron anyway, didn't offer a 50a/120v/3kw option, this is their new MPII line. The 'old' MultiPlus (which is still a good option) does have a 5kw option on the Quattro line. It all depends on how much AC power you need vs DC.
Adding more solar panels comes down to cost and space. Depending on your current setup, adding another solar panel, or two or three, could also mean needing another MPPT controller as well, so more costs. Everything adds up quickly Then physical space, and weight is a concern on mobile applications at least.
The inverter doesn't care how much solar panels you have though, only how much load it needs to handle.
The Eve cells are a great solution and probably closer to $3k for ~13kwh now, prices are going up everywhere. It's also a VERY much so DIY thing to build your own and supply your own BMS to keep them safe, build your own compression enclosure, etc. Very much doable with a lot of great info out there, but not for everyone.
I have 16 of the Eve cells myself with this new MultiPlus II. So I'm all for it, but it's definitely more work than say buying a battle born battery which can be an easy piece of mind for most folks.