Can you run a 12v compressor fridge straight from solar panels without a battery?

So I've been scratching my head over this one for a while and figured someone here would know the answer.

On the boat I've got a Victron MPPT running two 200W panels, and I'm wondering whether I could wire a 12v compressor fridge — looking at the Dometic CFX35 — directly off the solar output rather than going through the battery bank.

The reasoning is that the fridge is only really needed during the day when we're aboard and the sun's doing its thing. I'd rather not add another battery just for this circuit if I can avoid it.

My concerns though:

• Voltage spikes — panels can push well above 12v depending on the controller output, especially on a cold bright morning. Would that fry the fridge compressor over time?
• Intermittent supply — clouds roll over, output drops, fridge cuts out. Could that damage the compressor with repeated on/off cycles?
• Start-up draw — compressor fridges can pull a decent surge when they kick in. Would a panel setup handle that cleanly without a battery as a buffer?

I've seen a few YouTube videos suggesting it's "fine" but they're all American channels running in Arizona sunshine, not exactly comparable to the Thames Estuary in October.

Has anyone actually done this long-term on a boat or similar setup, or is the battery really doing more work here than I'm giving it credit for?

@BoatIan short answer: technically yes, but it's a really bad idea in practice.

The problem is compressor fridges — especially units like the Isotherm or Waeco/Dometic range — need a stable voltage to start. That compressor startup surge can be brutal, and solar output fluctuates constantly with passing clouds, shade, even a seagull landing on your panels. One dip at the wrong moment and you're either getting compressor stalls or tripping your MPPT's protection.

Your Victron MPPT is genuinely doing its best work as a battery charger, not a direct power source. The battery acts as a buffer, smoothing everything out beautifully.

I ran my cabin fridge panel-direct for about two weeks experimenting. Killed a compressor relay in the end. Expensive lesson.

Even a modest 100Ah Fogstar lithium would transform the reliability of that setup completely.

@JackeryGuy is right to flag it, but there's a specific killer detail worth adding: compressor fridges (Waeco, Dometic, Indel B etc.) have a startup inrush current that can be 3-5x the running draw. Without a battery acting as a buffer, your MPPT simply can't respond fast enough — you'll get undervoltage brownouts triggering the controller's protection circuits repeatedly.

Seen this exact failure mode on a tiny house build I did. Panels were more than adequate on paper, but every compressor kick-on caused the Victron SmartSolar to throw a fault.

Even a modest 20Ah LiFePO4 (Fogstar do decent budget options) acts as the buffer you need. The panels then top up the battery rather than powering the fridge directly.

Panel-direct can work with certain DC linear compressors designed explicitly for it, but that's a very specific product category — not standard marine compressor fridges.

@BoatIan had this exact "brilliant idea" on my narrowboat — the fridge compressor basically threw a tantrum every time a cloud drifted over, and the startup surge without a battery behind it was enough to make the Victron MPPT throw its hands up entirely.

The MPPT needs a battery to properly regulate output; without one, voltage swings wildly and your compressor motor windings won't thank you for the abuse — replacement compressors aren't cheap.

Even a modest 100Ah Fogstar Drift LiFePO4 acting as a buffer transforms the whole system — panels charge it, fridge draws from it, everyone's happy. Think of the battery as the sensible adult in the room between your panels and your fridge. 🧊

@BoatIan worth checking what your specific MPPT does when the load exceeds available solar. Some Victron units will just let the voltage collapse rather than gracefully shed load — compressor sees that as a brown-out and the thermal protection kicks in repeatedly. Kills the compressor eventually.

What panels have you got exactly? Two 200W in series or parallel makes a big difference to what voltage the MPPT is outputting on the load side.

On my static van I tried running a 12v Dometic directly off the load terminals of a Victron 100/30 during testing (no battery connected). Worked fine for about 20 minutes on a clear day, then a cloud passed and it cut out hard three times in a row. Battery is non-negotiable in my view — even a small 50Ah Fogstar would sort this properly.