Load battery at high energy costs while sufficient energy available in the battery

Been mulling this one over since I saw a similar setup discussion doing the rounds, and it's relevant to my static caravan situation so thought I'd throw it out here.

Running a Victron Multiplus-II with a Fogstar Drift 24V bank and a SmartSolar MPPT — works brilliantly most of the year. But here's the thing that's been nagging at me:

On days when the battery is sitting at, say, 80%+ by mid-morning and solar is cracking on nicely, should the system bother pulling from the grid at all during peak tariff windows? Mine sometimes does, and it drives me absolutely mad.

The logic should be simple — battery's got juice, sun's out, don't touch the expensive grid electricity. But the ESS settings in VRM aren't always intuitive about this, especially when you're juggling a scheduled charge window from an Agile-style tariff overnight.

I've been playing with the minimum SOC and grid setpoint values but feel like I'm going round in circles. There's also the question of whether the system should be topping up during cheap overnight rates even when the battery doesn't really need it — versus leaving headroom for morning solar.

Has anyone cracked a sensible ESS profile for a UK part-off-grid setup like this? Particularly interested if you're on Octopus Flux or similar where the export/import economics actually change the calculation entirely.

Feels like there should be a cleaner way to say "battery above X%, solar available, keep the grid relay firmly shut" without hacking around in Node-RED.

What are others doing?

@FellKev incomplete post there mate, you've cut off mid-sentence after "Multiplus-II" — what's the actual question?

That said, if you're heading where I think you're heading (using grid/generator to top up when battery's already got decent charge), the ESS assistant in VictronConnect is where you'd be looking. Specifically the minimum SOC and grid setpoint settings.

On my setup I've got it configured so it only draws from the grid when SOC drops below a threshold I've set — keeps the cycling sensible for LiFePO4 longevity.

Fogstar cells don't love sitting at 100% constantly either, worth factoring in.

@FellKev looks like the forum ate the rest of your post — happens all the time on here, especially on mobile. Worth editing it and reposting the full question.

That said, the topic title gives a decent hint at what you're after — sounds like you want the Multiplus-II to prioritise loads from the battery when grid tariff is high, rather than drawing straight from the mains. Classic ESS territory.

Plenty of us running similar setups so once you get the full question posted you'll get useful answers quickly. Static caravan is an interesting use case too — what battery chemistry are you running? That'll affect which ESS mode makes sense.

@FellKev the suspense is genuinely killing me — you've essentially posted the offgrid equivalent of a cliffhanger novel where the publisher forgot to print chapters 2 through 12.

That said, I'll have a stab at where you might be heading: if you're trying to configure the Multiplus-II to avoid charging from grid during peak tariff windows whilst still drawing from batteries, that's very much doable via VE.Configure or ESS settings — depending on whether you're running full ESS or just the basic assistant stack.

On my narrowboat I use the Ignore AC input scheduling trick to effectively ringfence battery use during expensive periods. Works a treat once you've wrestled the settings into submission.

Edit your post and give us the full picture — specifically your tariff setup and whether you've got a Cerbo/CCGX in the mix.

@FellKev while we're all awaiting the serialised conclusion of your post, I'll take a wild stab — you're probably asking about the Scheduled Charging feature in VenusOS, which lets the Multiplus-II top up from grid during cheap-rate windows (Octopus Go, Economy 7, etc.) only when SOC drops below a defined threshold, leaving solar headroom during the day. Set your minimum SOC trigger, your charge window, and the system does the maths. If you're on a static van with limited roof space, pairing this with a Fogstar Drift LiFePO4 and tight SOC limits (say 20–90%) means you're never paying peak rates to fill a battery that solar would've sorted by noon anyway — been running exactly this logic on my own setup for two winters without grief.

@FellKev mate, your Multiplus-II is doing more suspense-building than a BBC drama series.