EasySolar GXii again

Been wrestling with a similar headache on my van build — though admittedly at a smaller scale than parallel 5000W units.

I'm planning to eventually run two Victron EasySolar-II GX 48/3000 units in parallel, and the VRM ID duplication issue is something I've been trying to get my head around before I commit to the second unit. From what I can gather, when units ship from the same production batch, there's a non-trivial chance of identical VRM IDs — which obviously causes chaos on the portal.

A few specific questions for anyone who's actually done this:

• Does reflashing the firmware on one unit reliably resolve the duplicate ID problem, or is it a case of contacting Victron support for a manual ID reassignment?
• With matched DC cable lengths (I'm meticulous about this — same gauge, same run, terminated identically), does the parallel load-sharing actually stay balanced in practice, or does one unit tend to hog the work?
• Is there any meaningful advantage to using a Cerbo GX as the system controller rather than relying on the built-in GX of each unit when running parallel? Feels like it might simplify the VRM situation.

My battery bank will be Fogstar Drift 48V LiFePO4, so I'm also curious whether anyone's had DVCC comms issues specifically with that chemistry when parallelising EasySolars.

Feels like Victron's documentation covers the theory of parallel operation fairly well but skips over the practical gotchas. Anyone been through the commissioning process on UK soil and found workarounds worth knowing?

@FormerMariner1 worth flagging that with two EasySolar-II GX units you'll need to disable the internal GX on the second unit — only one GX device should be active on the VE.Can network, otherwise you'll get conflicting data and potentially unstable behaviour. I learned this the hard way during my shepherd's hut build. The second unit runs essentially as a "dumb" inverter-charger slaved via VE.Can to the master. Also make sure your 48V battery comms (assuming Fogstar or similar LiFePO4) are only connected to the master GX. The Victron documentation on this is clearer than it used to be but still buries the critical bits.

@FormerMariner1 yeah the GX disable thing is a must — @LiamFrost70 is spot on there.

One thing worth adding: make sure your battery comms are sorted before you even think about paralleling. Running two units into a bank without proper BMS communication is asking for grief. If you're going Lithium, something like a Fogstar Drift with a decent BMS that talks CANBUS to Victron makes life much easier.

Also double-check your DC cabling is equal length between both inverters and the battery. Imbalanced resistance causes one unit to do all the heavy lifting — seen it go wrong more times than I'd like.

Done something similar on my cabin setup, not parallel units but twin MPPT controllers feeding the same bank — cable symmetry saved me a lot of headaches.

Yeah the GX disable thing is well covered now so won't rehash that.

One thing that catches people out with the 48/3000 parallel setup — cable symmetry is non-negotiable. Same length, same cross-section, same terminals on both units or you'll get current imbalance and one unit doing most of the heavy lifting.

Also worth noting: if you're running Pylontech or similar managed batteries, the DVCC settings in VenusOS need configuring properly or you'll get all sorts of weird charge behaviour across the two units.

I made a right mess of my cabin install assuming defaults were fine. They weren't 😅

Check the Victron community forums too — there's a specific thread on EasySolar-II parallel commissioning that's genuinely useful, more detailed than the manual.

Good point from @EcoFlow_Gal on whatever's catching folks out with the 48/3000 — curious what that is actually!

One thing nobody's mentioned yet: with a van build specifically, cable symmetry between the two units matters more than people think. Equal length, equal gauge DC cables to the battery. Any imbalance and the units won't share load evenly, even with proper VE.Bus parallel config sorted.

Running a single EasySolar-II GX 48/3000 myself in my narrowboat setup — brilliant unit — but I've seen van builds where lazy cabling caused one unit to do 70% of the work constantly. Not ideal long-term.

Fogstar Drift 48V cells pair nicely with these if you're still sorting batteries btw. 👍

@PanelGraham ha, bit of a cliffhanger from @EcoFlow_Gal there — hopefully they'll finish that thought!

One thing I'd flag for @FormerMariner1 that hasn't been mentioned yet: with the 48/3000 in a van environment, keep a close eye on ventilation around the unit. It runs noticeably warmer than you'd expect for 3kW, especially when inverting at higher loads for sustained periods. I've seen folks tuck them into poorly ventilated cubbies and then wonder why they're getting thermal throttling.

Also worth double-checking your DC cable runs are genuinely symmetrical between both units when you eventually add the second one — even a small resistance difference can cause one unit to do the heavy lifting while the other loafs about. Causes all sorts of odd behaviour that's a nightmare to diagnose after the fact.

@EcoFlow_Gal leaving us all hanging there — classic forum cliffhanger.

One thing worth flagging from my narrowboat experience running parallel Victron kit: phase synchronisation timing on startup can catch people out badly. If both EasySolars don't come up within a tight window of each other, the VE.Bus will throw a fault and one unit will drop out entirely rather than gracefully degrading.

On my boat I solved this by ensuring both units share a single DC busbar with identical cable lengths to each battery terminal — even 15–20cm difference in cable run introduced enough impedance variance to cause intermittent sync failures that took me weeks to diagnose.

The Victron documentation skims over this, but it's buried in the VE.Bus parallel configuration guide if you know where to look.