Can you run a fridge 24/7 on solar + battery without killing the system?

Right, so I'm trying to work out if this is actually viable or if I'm just going to wreck my system within a year.

Got a static caravan setup with a 5kWh LiFePO4 bank (Fogstar), 3.5kW of panels, and a Victron MPPT. Running a decent chest freezer (not a fridge, but similar draw) plus general loads. Winter's killing me though — can barely get 2-3kWh generation on a grey day.

The question: if I run the fridge 24/7, what's actually going to break first? Is it the:

• Battery cycling constantly and degrading faster?
• Inverter struggling with the compressor startup current?
• My whole system just starving in January?

I've read fridges pull maybe 150-200W continuous average, but the compressor spikes are mental. I'm wondering if I need to upsize the inverter (currently 3kW Victron) or if the real issue is just not having enough solar generation during winter months.

Also, is there any point in oversizing the battery bank to handle longer discharge cycles, or does that just cost more and not actually solve the winter generation problem?

Cheers for any experience-based answers. Scattered my reading across too many YouTube channels and I'm getting conflicting advice.

Mate, you're fine with that spec. Fridge is one of the best loads for solar — compressor cycles mean you're not drawing constantly, and modern ones are pretty efficient.

5kWh Fogstar should comfortably handle a decent fridge's daily cycle, especially if you're getting decent sun. The 3.5kW panels will absolutely top you back up during daylight hours. I've run a 12V Dometic in my motorhome for months on similar sizing without drama.

Key thing: make sure your fridge is properly insulated and you're not constantly opening it in hot weather. Also worth checking your MPPT charge controller can handle 3.5kW — what've you got there? And do a rough load calc on your battery depth of discharge over 24hrs just to be sure, but honestly sounds like you've thought it through already.

Won't kill the system at all if the rest is sized right.

The real issue isn't the annual throughput—it's seasonal production variance. Your 3.5kW sounds decent on paper, but winter in the UK will gut your generation. December through February you're looking at maybe 40-50% of summer output, and that's on clear days.

Where you'll actually struggle: if your fridge draws 150-200W average (realistic for a modern unit), you need ~3.6-4.8kWh daily just for that appliance. Your 5kWh battery can technically cover it, but you're cycling 70-100% depth of discharge regularly, which hammers longevity even with LiFePO4.

The compressor cycling @WonkyMender mentioned is spot on—that's actually your friend here. But factor in ancillary loads (lighting, water, etc.) and you'll see why a cabin setup typically needs oversized battery capacity or a supplementary source for winter reliability.

What's your average daily consumption target? That'll tell you if you're genuinely viable or just pushing optimism.

The seasonal angle @TransitAdventure raises is the key one. Your 3.5kW is decent, but winter production in the UK will drop significantly — you might see 40-50% of summer output on grey days.

What matters is your daily fridge draw versus what you can realistically harvest November through February. A modern fridge pulls maybe 1-2kWh daily depending on ambient temp and usage patterns. Over a full 24-hour cycle, that's manageable, but you need to stress-test your winter numbers, not just summer.

Run a few weeks of data logging before committing to full-time reliance. Monitor how often you're dipping below 80% charge on typical days — if it's regular, you're undersized for winter. A 5kWh bank gives you decent buffer, but it won't compensate for consistently poor generation.

Fridges themselves won't damage the system; undersizing will. Check your actual winter production against worst-case draw scenarios.

I'd focus on the actual daily consumption figures rather than worrying about the theoretical annual throughput. A fridge typically pulls 100-150W when the compressor's running, but it's intermittent — maybe 8-10 hours daily depending on ambient temperature and how often you're opening it.

That puts you at roughly 1-1.5kWh per day. Your 5kWh battery gives you decent buffer, especially if you're getting decent solar input. The real stress point is @TransitAdventure and @RetiredPlumber's winter concern — spot on. November to February, you'll struggle to maintain full charge cycles, particularly in a caravan where you might not have optimal panel angle.

What's your actual setup — fixed panels or adjustable mounting? And where roughly are you based? That'll make the difference between this working smoothly or requiring some winter load-shedding.

The honest answer depends entirely on your fridge's duty cycle. A modern fridge pulls maybe 0.5-1kWh daily, which your 5kWh bank could handle—but only if your panels recover that battery loss daily. That's where it gets dicey.

@TransitAdventure and @RetiredPlumber have nailed the real problem: winter. You'll get maybe 0.8-1.2kWh from 3.5kW of panels on a December day in the UK. Your fridge plus basic loads will drain you faster than you're charging.

I've been through this with my own setup. The solution isn't oversizing the battery—it's accepting seasonal behaviour. Run the fridge year-round? Yes. But add a small backup (petrol genny or grid connection) for November through February, or plan for occasional top-ups.

Measure your actual fridge consumption first. Some newer units are brilliant; older caravans ones are energy vampires.