Has anyone actually run a 12v compressor fridge off solar alone — what size setup did you end up needing?

Thinking about ditching the icebox on my Transit-based van build and going for a proper compressor fridge. Been looking at the Alpicool C40 or the Brass Monkey 45L — both sit around 40–45W peak draw but drop to maybe 15–20W average once they're up to temp. Sounds manageable on paper.

My current setup is a single 200W panel on the roof feeding a 100Ah AGM, which works fine for lighting, phone charging and a 12v fan. But I'm genuinely not sure if that's enough headroom to keep a compressor fridge happy, especially on overcast UK days where I might only be pulling 40–60W from the panel for hours at a stretch.

I've seen people say you need at least 200Ah of battery and 300W+ of solar before a compressor fridge stops being a worry. Others reckon a decent 100Ah lithium paired with even a single 200W panel is fine because of the better usable capacity. Would love to know what real-world setups people are actually running, not just what the calculators say.

Has anyone made this switch and regretted it, or is it genuinely one of those upgrades where you wonder how you ever managed without it?

@PartnerConvert I've run a compressor fridge off solar on my boat for three years so can give you real numbers.

A 45L compressor fridge in decent UK temps will average 20–30Ah per day — duty cycle is everything, not peak wattage. That 40W figure is largely irrelevant.

My setup:

• 200W panel
• 100Ah lithium (Fogstar Drift)
• Victron SmartSolar 75/15

Works fine through summer. Winter is where it gets ugly — short days, fridge working harder in cold storage areas. You'll want at least 150–200Ah and 200W+ panels if you're planning extended winter use.

The Alpicool is fine but the Brass Monkey build quality is noticeably better in my experience. Worth the extra.

Don't scrimp on the BMS side if you go lithium — kills batteries faster than anything else will.

Great thread, just finished my Transit build last summer so got fresh numbers for you.

I'm running a Brass Monkey 45L with a 200W panel and a 100Ah lithium battery. Honestly that's the minimum I'd recommend — anything less and you'll be anxious on cloudy days.

Real-world draw is around 30-35Ah per day depending on ambient temp and how often you're opening it. Keep it out of direct sun and pre-chill your food before loading, makes a massive difference.

One thing nobody mentions — panel positioning on a van roof matters more than on a static setup. You're often parked at odd angles, so I'd suggest at least 200W even if the maths says less.

@BMS_Geek would be interested in your boat numbers actually, suspect the principles translate pretty well despite the different use case.

Really depends on your use case but my 12v Alpicool on the bench runs about 35–40Wh/day in a cool garage — reckon double that in a hot van in summer.

I'd say minimum viable setup for full solar dependency:

• 200W panel (ideally 2x100W if roof space allows)
• 100Ah LiFePO4 — Fogstar Drift is cracking value right now
• Decent MPPT, Victron SmartSolar if budget stretches

The fridge itself isn't the killer — it's cloudy UK weeks that bite you. Three days of Scottish drizzle will drain even a solid setup if you're not careful.

@BMS_Geek boat data is probably your best reference since ambient temps matter loads — what temperatures were you seeing onboard?