What size inverter do I need to run a fridge off-grid?

Right, skip the drama and just get a proper DC fridge — seriously, life-changing decision for us on the narrowboat. A 12V or 24V Waeco or Fogstar unit pulls maybe 40-50A running current, zero inrush nonsense, and your battery bank actually likes you.

If you're wedded to mains fridges (fair enough, they're cheaper upfront), then yeah, you need at least 4-5kW inverter to handle the startup spike — @DriftWizard's right about that being teeth-rattlingly brutal. But that's suddenly a massive battery bank investment, plus the standby losses are mental.

The real question: are you running the hut 24/7 or seasonal? If it's weekend use, a DC fridge barely dents your Victron system. If it's permanent, suddenly a 3kW Pure Sine and a beefy battery setup starts looking reasonable, but you'll want to invest in a soft-start or one of those clever relay modules to manage the inrush.

What's your current battery capacity looking like?

A proper DC fridge is the obvious move here — @CornishNomad's spot on — but if you're set on a conventional unit, you're looking at a 3000W inverter minimum to handle the compressor inrush, probably 5000W if you want any headroom for other loads. The issue is those initial current spikes can be 3-5x the running draw.

That said, with a 48V Victron setup you've already got the infrastructure sorted. A Victron MultiPlus 48/3000 would do the job, though it'll hammer your batteries on a fridge cycle if you haven't got serious capacity behind it.

Real talk from my narrowboat days — running a conventional fridge off-grid is a false economy. DC models like Dometic or Waeco are thirsty but predictable, and you'll actually know what you're getting. Beats sizing an inverter big enough to handle phantom loads and efficiency losses.

What's your current battery capacity looking like?

The inrush thing @WattKaren mentioned is real — I learned that the hard way when I first converted my van. Conventional fridges pull absolutely mental current for the first couple of seconds when the compressor kicks in. I was running a 2000W Victron and thought I'd be fine, but the fridge would just trip it constantly.

That said, if you're dead set on a conventional unit, you're looking at minimum 3000W to handle the startup surge safely. Even then, you might get nuisance shutdowns depending on what else is running.

But here's the thing — I've since switched to a Fogstar 12V DC compressor fridge on the boat, and it's genuinely transformed the setup. No drama, no massive inverter needed, and your battery bank actually thanks you for it. The running draw is a fraction of what a conventional fridge demands.

What's your actual battery capacity? That might make the decision clearer. If you've got decent storage, the DC route is honestly worth stretching the budget for.

The inrush current is the killer most people overlook. Your fridge compressor will pull 3-5x its running wattage on startup — that's the real story here.

I went down this road with a shepherd's hut setup similar to yours. Started with a 3kW Victron and thought I was sorted, but the fridge would cause the whole system to hiccup every time the compressor cycled. Frustrating as hell.

What actually worked was either going bigger (5kW inverter, which felt daft for a 500W fridge), or — and this is what stuck — switching to a proper 12V DC compressor unit. Grabbed a Fogstar and never looked back. No inrush drama, sips power compared to conventional fridges, and plays nicely with battery systems.

If you're really wedded to a conventional fridge, you'll need either:

• Inverter oversized by a factor of 3-4 minimum
• A soft starter module (pricey, fiddly)
• Or accept you're going to need a chunky battery bank to buffer the inr

Been through this exact headache with my van conversion. The inrush spike is genuinely the issue here — you'll need to size for that, not just the running wattage.

What's your actual battery capacity and current load? That matters more than people think. A 3kW inverter sounds safe on paper for a fridge that draws 600W running, but if you've got a modest 48V system you might struggle with the voltage sag when the compressor kicks in.

Have you considered a hybrid approach? I'm running a small DC compressor fridge (Fogstar or similar) as my primary, with a conventional one on an inverter for overflow during summer. Cuts the inverter size needed dramatically and takes pressure off the batteries.

If you're dead set on conventional, what's your battery bank looking like — LiFePO₄ or lead? And are you planning to run anything else simultaneously? That'll determine whether you genuinely need 3kW or if a quality 2kW pure sine wave would do the job with careful load management.

The lads are spot on about inrush — that's where most people come unstuck. Here's the practical bit though: you need to size for the peak demand, not just the running wattage.

A typical fridge compressor draws maybe 150-200W running, but that initial kick when it fires up can hit 600-800W. Your 48V setup is good for this because you're already in decent territory voltage-wise.

I'd honestly recommend a 3kVA minimum for a proper comfort margin, especially if you're planning to run anything else simultaneously (kettle, microwave, etc.). That said, if it's just the fridge with nothing else, a quality 2kVA would technically work — but you're cutting it fine.

What matters more than the size is the inverter's surge capability. Victron's MultiPlus range handles inrush brilliantly because of how they manage the switching. Avoid the budget Chinese units that claim 3kW but can't actually deliver the surge.

What's your battery capacity looking like? That'll affect how quickly the inverter can recover between compressor cycles. If you're on a smaller bank (say, 200Ah or under), you might notice voltage sag, which can trip protective circuits.

You're absolutely right about the inrush — it's mental. I've got a similar 48V Victron setup in my motorhome with a decent chest fridge, and I went 5kW to handle the compressor kick comfortably.

The thing nobody mentions much though: fridge duty cycle matters loads. A chest fridge pulls maybe 300-400W running, but that inrush can spike to 2kW for a few seconds. If your battery state's dodgy or the weather's overcast and your solar's weak, the inverter can struggle.

What I'd actually suggest — if your budget's tight — is looking at a 3kW Victron and then just be disciplined about when you open the door and what else you're running. Kettle off when the compressor kicks in, that sort of thing. Pain in the arse, but it works.

Alternatively, if you've got space, a proper stand-alone 12V fridge might suit you better. Waeco or Engel units sip power compared to standard fridges, no massive inrush either. Bit more expensive upfront but

Inrush is definitely the killer here. I ran a standard fridge off my narrowboat's 48V for years and learned the hard way — you need way more than the running watts suggest.

Grab a 3000W minimum for a proper kitchen fridge, ideally 3500W. The compressor startup pulls mad spikes, easily 3-4x the steady-state draw. A Victron MultiPlus would be ideal for your existing setup if you've got the battery capacity.

One thing the others haven't mentioned: check what fridge you're actually after. A smaller chest freezer or caravan-spec unit (like a Fogstar or similar) will be much easier on your system than cramming in a full-size domestic one. Saves you money and stress.

Also worth checking your battery voltage won't sag under load — that's what triggered most of my issues. Undersized batteries + undersized inverter = nightmare.

What's your battery bank like currently?

Fridges are deceptive — the inrush current is brutal. Depending on the compressor type, you're looking at 3-5x the running watts for a second or two when it kicks in.

For a proper fridge (not a tiny 12V thing), I'd say minimum 3000W inverter on 48V, but honestly 5000W is the sweet spot if your battery can handle it. What's your current battery capacity? That matters as much as the inverter size.

Thing is, even with headroom on the inverter, you need to check your battery bank can actually supply that inrush without sagging the voltage too hard. A Victron MultiPlus 48/3000 could work, but it'll be stressed every time the compressor engages. I've seen folk go with the 48/5000 and never regret it.

Are you planning mains backup or pure off-grid? Makes a difference to whether you can get away with smaller.

The compressor startup is genuinely the gotcha nobody talks about until it's too late. I've been through this twice — once in the motorhome, once when I set up the cabin.

What actually matters is your battery voltage stability during startup. I found that a modest fridge (like a Fogstar or similar) drawing maybe 4-5A running current needs a 5kW inverter minimum on 48V to handle the inrush without your voltage sagging and triggering protection shutdowns. Sounds overkill for continuous load, but you're not paying for continuous — you're paying for those brutal startup spikes.

The real win is battery bank size though. If your battery can't handle the voltage dip, even a 5kW inverter won't save you. I run 400Ah lithium and it barely flinches. Friends with 200Ah lead acid? Constant drama.

Also worth considering: does the fridge have to be a standard AC unit? Proper 12/24V compressor fridges (Waeco, Dometic) draw way less inrush and are honestly more sensible

Yeah, inrush is definitely the problem child here. I've got a Fogstar fridge in my garden office setup and learned that lesson properly.

Running calculation: your fridge probably draws 150-200W continuous, but the compressor startup? You're looking at a solid 800W+ spike. I'd go 3000W minimum on the inverter to be safe — gives you headroom and stops the Victron from throttling.

One thing that actually helped me: soft-start devices. They're not expensive and genuinely reduce that compressor kick. Also, if your 48V setup is modest, check your battery voltage stays stable during startup — that's what kills inverters as much as the actual current draw.

What's your current battery capacity? That matters more than people think for fridge duty. A bigger bank means steadier voltage = happier inverter.

Right, you've got the hard truth from the others on inrush — I'll add the practical bit from my own emergency backup setup.

I'm running a 48V system like yours with a Victron Multiplus, and I learned the painful way that a standard fridge absolutely hammers the inverter on startup. The compressor can pull 4-6kW for a fraction of a second, which will trip most kit.

For a shepherd's hut scenario, you've got two sensible routes:

Oversizing the inverter — go 5-6kW minimum if you're serious about reliability. Sounds mental, but you're not drawing that continuously; you're just giving headroom for the compressor. A Victron 5000-48 will handle it without breaking a sweat and costs less than replacing failed equipment.

Soft-start module — if budget's tight, a Victron SCP060450200 or similar reduces inrush to manageable levels. Not cheap, but means you can run a smaller inverter (3kW) without the cardiac event when the fridge cycles.

What's your

Spot on about the inrush — caught me out when I first set up the motorhome. Thing is, a standard fridge compressor can pull 3-4x its running wattage on startup, so you need headroom you wouldn't expect.

For a shepherds hut setup, I'd honestly recommend sizing for at least 5kW if you've got other loads, or 3.5kW minimum if it's fridge-only. With your 48V Victron system, a Multiplus II would handle it beautifully, though they're not cheap.

The alternative I went with on the camper was accepting the fridge takes priority — I'll kill non-essential loads the second I hear the compressor kick in. Works fine if you're disciplined about it.

One thing nobody mentioned yet: soft starters. They're not magic, but a quality one genuinely does reduce that initial surge. Adds maybe £200-300 to the build, worth it for peace of mind.

What wattage is your current fridge pulling when it's running? That'll help nail whether you're talking 3.

The inrush spike is the gotcha nobody mentions until you've tripped your inverter at 3am. Worth knowing that most domestic fridges pull 3-5x their running current when the compressor kicks in — so if it's rated at 150W continuous, you're looking at 600-750W on startup.

For a 48V system, I'd honestly go 3000W minimum if you want headroom for anything else running simultaneously. Learned that the hard way with my motorhome — a 2000W Victron looked fine on paper until I tried using the kettle while the fridge was cycling.

The alternative nobody talks about enough: get a 12V fridge designed for off-grid instead. Waeco/Dometic make decent ones, lower inrush, no inverter inefficiency losses eating your battery. Takes a bit more solar to charge, but your battery lasts longer overall.

What's your current battery capacity? That'll make a bigger difference to how happy you'll be than the inverter size — a fridge running off a weak battery is a misery.

The garden office fridge saga taught me that inrush current is basically a fridge's way of saying "surprise, I need triple my running watts for exactly 0.5 seconds" — caught my Victron 3000 napping once and won't make that mistake again.

For a shepherd's hut you'll want at least 4000W continuous if you're running anything else simultaneously (kettle, tools, etc). Pure fridge duty? 2000W should handle most domestic units, but honestly I'd size up to 3000W minimum and call it peace of mind.

The 48V setup plays nicely here — better efficiency than 12V nonsense. If you're already Victron'd up, their multiplus range won't let you down, though they're not cheap. Fogstar do decent budget alternatives if the wallet's looking thin.

Real talk though: measure your actual fridge's plate specs first. Some older models are absolute power hogs, some modern ones barely hiccup. And factor in any other simultaneous loads — nothing kills the vibe like your inverter going offline because you tried toasting bread whilst the comp