Charger only mode, MP2, is a set grid code applicable?

Been thinking about this after a similar conversation I spotted recently about grid codes and the MP2 — thought it was worth raising here for UK installs.

My garden office setup is grid-tied but I frequently run it in a sort of hybrid off-grid mode when I want to avoid peak tariff hours. Got ESS running on the Multiplus II and it's all been fine, but I've started wondering about the edge cases.

Specifically — if I have a grid code set (in my case the standard UK G98/G99 compliant profile) and I deliberately disconnect from the grid for a period, does that grid code cause any headaches when running purely on battery + solar? I've had the unit drop into what feels like a "charger only" state a couple of times after reconnecting, and I'm wondering whether the grid code settings are interfering with how the ESS assistant handles the transition.

A few things I'm not clear on:

• Does the active grid code profile affect inverter behaviour when the AC-in is physically disconnected?
• Should I be switching profiles, or is there a cleaner way to handle intentional grid disconnection without confusing the ESS logic?
• Has anyone used VE.Configure to create a workaround for this kind of switching scenario?

Running firmware 498 on the MP2 5kVA if that's relevant. Victron's documentation is decent but it doesn't really address this specific scenario cleanly — at least not that I've found.

Curious whether anyone else running a grid-tied setup with occasional deliberate islanding has hit this. Feels like it shouldn't be complicated but the interaction between grid codes and ESS isn't exactly transparent.

@FormerMariner24 worth clarifying what you're actually asking here — are you talking about running the MP2 purely in charger-only mode with no inversion happening at all, or a hybrid setup where it occasionally exports?

Because if it's genuinely charger-only (so no energy flowing back to grid), my understanding is you're essentially just operating a large battery charger and G98/G99 notification requirements arguably don't apply in the same way.

That said, Victron's own documentation is frustratingly vague on this distinction for UK installs. I've had this exact grey area with my static van setup — DNO wasn't interested when there was zero export capability configured.

The pedantic answer is: it depends on your exact configuration and whether your DNO considers the inverter's potential to export, regardless of how you've set it up in VictronConnect.

What does your install actually look like?

@DODGuy raises a fair point about clarifying the question, so I'll add my two penneth from experience.

When I set my MP2 to charger-only via VEConfigure, I specifically asked my DNO about grid code obligations. Their position was that if you're only drawing from the grid — no export whatsoever — G98/G99 registration doesn't apply in the same way. The anti-islanding and frequency response requirements are really about what you push back onto the network.

That said, my installer still configured the grid code settings correctly in VEConfigure as a precaution, because switching modes later without proper setup causes headaches.

Worth checking your specific DNO's supplementary conditions though — Western Power were quite different to what UK Power Networks told a mate of mine running a similar Victron setup in Essex.

@FormerMariner24 on my narrowboat I've run the MP2 in charger-only mode (switch position 1) for periods when I'm hooked up to shore power and don't need inversion. In that configuration it's not injecting anything back to grid, so G98/G99 requirements don't apply in practice — it's functionally no different to a quality battery charger as far as the DNO is concerned.

Where it gets murkier is if you're using the grid setpoint feature in ESS and accidentally allow export. That's where the grid code question becomes relevant.

If you're purely charging and have export blocked in VEConfigure, I wouldn't lose sleep over it. Worth double-checking your ESS assistant settings if you're using that rather than pure charger mode though — easy to have something configured that allows brief export during transitions.

@YorkshireVanLifer one correction worth making — switch position 1 on the MultiPlus-II is actually inverter off, charger on, which is charger-only mode, yes, but the grid code question is still relevant even here.

The grid code is embedded in the unit and applies regardless of operating mode. In charger-only, the MP2 is still drawing from the grid in a managed way, and DNOs have been known to ask for documentation during installs even when there's no export involved.

For a GB/UK install you'd typically be looking at G98 or G99 depending on capacity. Below 3.68kVA single-phase export, G98 self-notification applies — but if you're genuinely charger-only with no export, it gets murkier. Worth checking with your DNO directly rather than assuming.

VEConfigure will show you which grid code profile is currently loaded.