Anyone else running a Victron Multiplus with a small UK grid-tied solar setup — how are you handling the G98/G99 nonsense?

So I've finally got my 3kW rooftop array feeding into a Victron Multiplus-II 48/3000 alongside a 200Ah lithium bank, and honestly the setup works a treat except for the grid compliance headache. My DNO (Scottish and Southern) keeps asking about G98 certification and whether the inverter is on the approved list for export. I'm not exporting intentionally — just using the grid as backup — but apparently that doesn't matter if the unit can export.

The Victron firmware has an option to set it to "anti-islanding" mode and cap export to zero, which I've done via VE.Configure. I've also got the ESS assistant loaded. But I'm still getting letters asking me to prove compliance, and the MCS installer I spoke to basically shrugged and said it's a grey area for retrofit battery systems. Not exactly helpful at £150 an hour.

Has anyone actually gone through the proper notification process with their DNO for a setup like this? I'm wondering if it's worth getting a G98 self-notification done even though the solar was originally installed pre-2019 under the old rules. Or is there a simpler way to configure the Multiplus so it's definitively in "storage only" mode with no possibility of grid export? Would love to hear what others have done, especially if you're in the SSE/SP Energy Networks area.

Hey @HarryMorgan, know exactly where you're coming from! The G98/G99 distinction is what trips most people up — G98 covers you for installs under 3.68kW per phase without needing prior DNO approval, but you still have to notify within 28 days. G99 kicks in above that or for anything the DNO deems "non-standard," which can get expensive and slow.

With a Multiplus-II the key thing is making sure your ESS assistant is configured so the unit isn't exporting unless you've got explicit DNO permission — a lot of people get caught out assuming self-consumption mode automatically keeps them compliant. It doesn't necessarily.

Have you registered with your DNO yet? Some are quicker than others — Western Power are fairly painless, National Grid less so in my experience. Worth getting that paperwork sorted sooner rather than later!

Hey @HarryMorgan, great setup by the way! Just to add to what @Curly66 was getting at — one thing that really helped me was making sure the Multiplus-II's grid code was properly set to G98 (assuming you're under 3.68kW export). The default European grid code won't cut it for UK DNOs. In VEConfigure you'll find it under the grid tab — select "UK G98" specifically. Also worth checking your export limitation settings if your DNO has capped you, as the Victron can throttle output via its assistant framework. Have you registered with your DNO yet? Under G98 it's technically notify-only rather than approval, which makes life considerably easier. What firmware version are you running? Some earlier versions had quirks with the UK grid codes that were sorted out later.

Great thread @HarryMorgan. Just to add to what @Curly66 was getting at — the key thing people often miss is that G98 applies to single-phase systems under 3.68kW export, which most domestic setups fall under, so you're likely fine with a straightforward notification to your DNO rather than needing full G99 approval. With your Multiplus-II, make sure your grid code settings match your DNO's specific requirements — some are stricter than others on frequency/voltage ride-through tolerances. I'd also strongly recommend getting your installer to confirm the export limitation settings are properly configured if you're not going full export, as that can satisfy a lot of DNO concerns before they even raise them. Have you spoken to your DNO yet, or still at the planning stage?

Running my Multiplus-II on the caravan setup and the bit nobody tells you is that your DNO's interpretation of G98/G99 varies by region — what Western Power District waves through, Scottish & Southern will send back with a strongly-worded letter and a six-week wait.

If you're under 3.68kW inverter output you're theoretically G98 territory, but the moment your Multiplus starts exporting and the DNO clocks a grid-interactive battery they sometimes want full G99 — because reasons.

Get your application in writing, keep every email, and if they query the battery just describe it as a "load management device" and watch their confusion buy you three months.

@MoorRuss is absolutely right about DNO interpretation — I ran into exactly this with my narrowboat's shore power setup last year. Western Power basically invented requirements on the spot that weren't in the actual G98 document.

What saved me was downloading the actual G98 notification form direct from the Energy Networks Association rather than relying on what my DNO's helpline told me over the phone. Night and day difference.

One thing nobody's touched on yet: if your export is genuinely under 3.68kW per phase, G98 is notification only — you don't need approval. Victron's ESS assistant handles the frequency shifting for islanding protection automatically, so the compliance side is largely sorted in firmware. The paperwork is the real enemy here, not the hardware.