How do you deal with really unstable grid power with a Victron system?

Q&A and troubleshooting
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1

I’m in a location with extremely unstable grid (voltage swings, frequency dips, lots of noise). I’m running a split-phase setup:

2× Multiplus II 12/3000 (split phase)

1× SmartSolar 150/70 MPPT

480Ah LiFePO₄ battery

Cerbo + GX

1.5 HP well pump (requires soft start or transformer – not running it yet)

The Multiplus units struggle with the grid. At night, even with small loads (1000–1400W), I get:

Flickering in/out of grid

Inverter alarm flashes

Frequent disconnect/reconnect cycles

Unstable behavior unless I severely limit grid amps

System works great when running purely off solar and battery.

The problem is only when mixing grid and inverter.

I know an Isolation transformer solution is popular, but before I spend $1,000–$1,500:

Is anyone successfully stabilizing terrible grid WITHOUT a transformer?

If so, what configuration worked for you?

Examples I’m curious about:

Lower grid current limit?

Charger limit strategies?

Boost factor tweaks?

Weak AC input on/off?

UPS mode on/off?

No LOM protection?

Advanced AC input settings you’ve found stable?

Does balancing loads on L1/L2 help long-term?

Any success running a 1.5 HP pump on similar grid?

Just looking for real-world experiences from people who deal with genuinely bad grid power and have made Victron behave.

Thanks!

2

With really bad connections we just have the system full time inverting. Whats the point of having the rubbish grid in your loads?
Then use a separate inverter for charging when needed with some simple programming.

are you runnjng ESS assistant or just ac ignore?

When connecting to bad grid you are treating it like a really poorly regulated generator in settings so refer to the generator faq manual.

With older firmware yes. But with newer (since the generator improvements, no.

Yes off.
Wide frequency on.

I found one site where if i labelled it as grid kn the gx it helped as well. (Looks bad in stats. But anyway)

Also have a node red flow on one (with ess) that varies the input current limit based on grid voltage to prevent the cutting in and out)

Never done a split phase FYI Just what i have seen with parallel and three phase set ups.

3

This.

Just forget trying to stabilise something that poor. Find a way to charge your batteries with the grid through a separate charger.

4

The best example of an unstable grid… :sweat_smile:

1 Like
5

Yes exactly, an Eltek Flatpack 2 48/2000 or so could work well.