Anyone else noticed their energy bills actually went up after going partial off-grid?

Ran into exactly this with my cabin setup about 18 months ago. Partially disconnected from the grid thinking I'd slash my standing charges and consumption — ended up paying more for about four months straight.

The issue nobody really talks about is base load behaviour. When you're pulling some loads off-grid, you change your consumption pattern on the grid side, not just the volume. My supplier (Octopus at the time) had me on an Agile tariff and I was inadvertently missing the cheap overnight windows because my Victron system was handling overnight loads through my Fogstar Drift cells. So the grid draws I did make were clustered into peak periods. Bill went up roughly £40/month.

A few things worth checking if you're in the same boat:

• Export/import balance — if you're on a smart meter, your supplier can see exactly when you're drawing and may be tariff-matching you poorly
• Standing charge absorption — you're still paying it regardless, so if you've reduced consumption without reducing the charge tier, your cost-per-kWh efficiency tanks
• Inverter idle draw — my Multiplus was pulling a surprising amount just sitting there, which I was attributing to "off-grid" but still came from the grid overnight

It genuinely took me about three months of spreadsheet logging to untangle what was happening. Once I restructured which loads stayed grid-side and optimised the Agile slots properly, it corrected itself.

Anyone else found specific tariff structures that work better alongside a hybrid battery setup? Curious whether Intelligent Octopus handles this better than standard Agile for people with significant battery storage.

@WezWhite72 this is really interesting — what was the actual cause in your case?

I'm mid-way through planning my garden office setup and I keep reading conflicting things about whether partial off-grid actually pencils out financially in the UK. My concern is exactly this — you still pay the standing charge regardless, so if you've reduced your grid consumption but kept the connection, you're paying ~£110/year just to have the meter before a single unit is used.

Did you find your overall solar system efficiency dropped during those winter months? I'm wondering whether the maths only works if you go fully off-grid or have a substantial Victron/Fogstar battery bank to actually cover your baseload overnight rather than just daytime peaks.

Was your monitoring granular enough to pinpoint where the money was disappearing?

@WezWhite72 really curious about this — did you find your grid import timing shifted at all? I've been planning a cabin/emergency backup system and one thing I keep coming back to is whether partial setups accidentally push you into peak-rate periods more than before.

Like if your solar and batteries handle the cheap overnight charging window but you're then pulling from the grid during the day when your system can't quite keep up — could that flip the economics entirely?

Also wondering whether anyone's run into issues with standing charges not actually reducing because your DNO won't let you drop to a lower tariff without full disconnection. That feels like a hidden trap nobody warns you about upfront.

What monitoring setup are you using @WezWhite72? I'm looking at Victron kit partly for the data granularity — seems like you'd need really detailed import/export logs to even diagnose this properly.

@WezWhite72 had almost the exact same experience with my garden office build — genuinely baffling for the first couple of months.

The culprit for me was overnight grid draw. My Victron MPPT was doing brilliantly through the day, but I'd unconsciously shifted heavier loads to evenings once I felt "guilt-free" about consumption. Net result: daytime grid import dropped, but I was hammering peak-rate electricity after dark.

Once I added a Fogstar 200Ah lithium bank and actually looked at my Victron VRM data, the pattern was obvious. The behaviour change matters as much as the hardware.

@PartnerNomad — yes, import timing absolutely shifts. That's worth modelling carefully before you commit to your cabin layout. Where are you planning to run your heavy loads?

@WezWhite72 what meter type are you on? Because I went through something similar with my garden office setup and eventually traced it back to my smart meter misreporting periods where the system was in transition — essentially double-counting some consumption.

Also worth asking: did your standing charge actually change, or did you assume it would? That caught me out badly. Moving partial off-grid doesn't automatically renegotiate your tariff — you're still paying full standing charge regardless.

The other thing nobody mentions — smaller grid draws become proportionally more expensive per kWh once your cheap self-consumption drops off. Your unit economics flip entirely.

What does your Victron (or equivalent) show for grid import vs what the supplier is actually billing? That discrepancy told me everything I needed to know about where my problem was.