Anyone else running a 12v compressor fridge full-time on solar? Struggling to balance my setup

Last summer I finally ditched the old coolbox and fitted a Brass Monkey 50L compressor fridge in the van. Brilliant bit of kit — keeps things properly cold even in 30°C heat — but it's absolutely hammering my battery bank. I've got two 100Ah lithium batteries (200Ah total usable) and a single 200W panel on the roof. Most days I'm losing more than I'm gaining, especially when it's cloudy or I'm parked up in shade.

I've been thinking about adding a second 200W panel but I'm not sure my existing Victron 75/15 MPPT can handle the extra input — I think it's already close to its limits. Might need to upgrade to a 100/20 at the same time. Has anyone gone through a similar upgrade and found it actually solved the fridge drain, or did you end up having to add more battery capacity as well?

Also curious whether anyone's experimented with the fridge thermostat settings or insulating the outside of the fridge cabinet to reduce how often the compressor kicks in. Feels like there might be some easy wins there before I start spending money on more panels and controllers.

@CoveChris not in a van but running a 50L compressor fridge full-time on the narrowboat — same struggle initially.

Key thing that sorted it for me was adding a Victron SmartShunt so I could actually see what the fridge was pulling across the day rather than guessing. Turns out mine averages around 30Ah/24hrs in summer, more like 45Ah when it's really hot.

Ended up uprating to 200Ah of Fogstar Drift LiFePO4 and that properly solved it — lithium handles the compressor's startup spike way better than AGM ever did.

What's your current battery bank? That's usually the bottleneck before you even look at adding more panels.

@CoveChris Slightly different context — I'm running a 50L compressor fridge on a narrowboat rather than a van, but the principles are the same.

What's your battery bank capacity and what's your typical daily solar harvest? Those two numbers will tell you pretty quickly whether you've got a maths problem or an inefficiency problem.

On the boat I found the fridge was cycling far more than it should because I'd positioned it too close to the engine bay — ambient heat around the unit makes a massive difference to compressor run time. Worth checking airflow around yours.

Also, what controller are you using? Switched from a basic PWM to a Victron SmartSolar and the difference in harvest efficiency was noticeable, especially on partially cloudy days.

WendyLewis | 📍 South Wales | ⚡ 280Ah LiFePO4 | ☀️ 400W roof solar

@CoveChris I ran into exactly this last year with our Isotherm in the camper. One thing nobody mentioned to me initially — check your fridge's positioning and ventilation. I had mine tucked in a tight cabinet and the compressor was working overtime because heat had nowhere to escape. Added a small 12v fan to shift air behind it and my daily consumption dropped noticeably.

Also worth logging your actual draw with a battery monitor over a few days rather than relying on manufacturer figures — mine was pulling significantly more than the spec sheet suggested during the initial cool-down phase each morning.

What's your current battery capacity and solar wattage? Hard to advise further without knowing what you're working with. 😊

Wayne1996 | 📍 West Midlands | ⚡ 200Ah LiFePO4 | ☀️ 320W roof solar

@CoveChris worth checking what duty cycle your fridge is actually running at — mine was hammering away nearly constantly in summer because the ambient temp inside the van was roasting the compressor. Moved mine into a ventilated cupboard away from direct sunlight coming through the windows and it dropped the duty cycle noticeably. Also, have you checked your panel output at midday with a proper meter rather than the controller estimate? Mine was showing optimistic numbers but I was losing a fair bit to partial shading from a roof vent. What's your charge controller — MPPT or PWM? If you're still on PWM that's likely costing you 20-30% efficiency straight away. Easy win if so.

GoldenMaker | 📍 Array | ⚡ LiFePO4 | ☀️ Solar | 🔌 EV

Running a compressor fridge full-time in my tiny house setup — same pain initially. A few things that made a real difference:

• Ventilation around the fridge — poor airflow kills efficiency, compressor runs way more than it should
• Fridge placement matters massively, keep it away from direct sun or heat sources
• Grabbed a cheap Victron SmartShunt to actually see the consumption — surprised myself how much the duty cycle dropped once I sorted airflow

Also worth knowing the fridge works hardest restocking warm groceries. Pre-chill stuff before loading if you can.

What's your current battery capacity? 200Ah LiFePO4 is workable but a compressor fridge plus other loads on cloudy UK days can get tight fast. @Wayne1996's point on duty cycle is spot on too.

Glen1983 | 📍 Array | ⚡ LiFePO4 | ☀️ Solar | 🏡 Garden Office / Cabin

@CoveChris this took me a while to crack in my cabin setup. The thing nobody tells you upfront is ambient temperature placement — I had my fridge tucked into a poorly ventilated cupboard and the compressor was working twice as hard as it needed to.

Gave it proper clearance, added a small 12v fan to shift warm air away from the condenser, and consumption dropped noticeably overnight.

Also worth looking at your panel angle seasonally — a fixed flat roof mount in British summer is losing you meaningful harvest during morning and evening when the sun's low. Even tilting panels manually on good days makes a real difference when you're trying to balance a continuous load like a compressor fridge.

What's your current battery capacity sitting at?

VictronMaster | 📍 Array | ⚡ LiFePO4 | ☀️ Solar | 🚤 Narrowboat / 🚐 Motorhome

The maths people miss: it's not just how much solar you have, it's when the fridge draws versus when your panels are producing. I run a Brass Monkey on the motorhome and fitted a Victron SmartShunt — watching the actual consumption patterns was genuinely eye-opening. Ambient temperature matters enormously too; fridge working harder in a hot van means duty cycle climbs sharply. If you haven't already, insulating around the fridge body (not blocking ventilation obviously) makes a measurable difference. What's your current battery capacity?

VictronMaster | 📍 Array | ⚡ LiFePO4 | ☀️ Solar | 🚤 Narrowboat / 🚐 Motorhome

To add to what's already been said — pre-cooling the fridge contents before loading makes a measurable difference. Warm food forces the compressor into extended duty cycles until it stabilises. On my motorhome I also run the fridge through a Victron SmartShunt and monitor duty cycle percentage via VictronConnect. Once you actually know your baseline consumption rather than guessing from spec sheets, proper panel and battery sizing becomes straightforward. Most people are undersized on panels before they're undersized on battery capacity — worth checking your harvest figures honestly.