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Small Sailboat Solar Refrigeration

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The system unpacked on my dinette table.

Using the power of the sun to keep beer cold.  I love it.

Update December 2012: Marine 12V refrigeration systems suck a little more power than I thought.  Keep reading, and also check out Windpower for how I had to modify my electrical generating systems.


holding plate

The holding plate sitting in the back of my icebox. I still need to remove the tubes from my old system, seen on the upper right.

Technautics Cool Blue DC Refrigeration

I just purchased a Technautics Cool Blue 12V DC holding plate system to replace my engine-driven holding plate system.

What’s a holding plate?  It’s a metal box filled with a eutectic solution, through which R-134a refrigerant passes in an array of tubing.  The refrigerant freezes the solution and it creates a sort of reusable block of ice to keep an icebox cold.

As with everything I do, I noticed some funny looks when people heard I’d be getting rid of my engine-driven system in favor of a 12V DC refrigerator system.

For the most part, I think it’s absolutely ridiculous for somebody who lives on a sailboat to be required to crank up the engine once or twice a day for an hour at a time.  Talk about killing the peace and quiet!  And wasting fuel!  And engine life! My 30-year old engine has 1,150 hours on it and an engine-driven refrigeration system for a liveaboard would put between 500-750 hours on it annually.

What’s the difference between an evaporator plate and a holding plate?

Evaporator plates cycle on and off dozens of times throughout the day and hold a nearly constant temperature.  This means cycling at night too when the solar panels aren’t outputting anything.

Holding plates only cycle a couple of times per day and the temperature range is more variable.  The Cool Blue has a thermostat to kick the compressor on whenever the holding plate drops below a certain temperature.

Cool Blue Applications

You could also build separate refrigerator & freezer compartments with this system, but I’m just going with the fridge.  I might try to keep an ice tray right next to the holding plate to make some ice.  What a luxury!

All in all, I think this is the perfect sailboat refrigeration system for someone like me who won’t be using it every single day.  I’ll only need to use it when I have perishable food in my stores.

And it’s efficient, so there’s that.

Refrigerator Installation

refrigeration installation

The shelf under my berth, showing the compressor mounting bolts.

My engine-driven system took up a lot of room.  It had a larger compressor, a belt from the engine, a seawater condenser, and a receiver.

This new system is all in one unit, 10″ x 12″ x 9″, and is air-cooled with a fan, meaning I don’t have to suck cooling water from my engine or cut another dreaded hole in my hull.  It’ll fit in any well-ventilated space.

I chose to put it in a storage area under my berth.  At first, I was worried about the noise from the motor while I was sleeping.  But I’m going to try only running this during the day, hopefully when the sun is on my solar panels.

I made a shelf out of plywood and mounted it inside of this storage space.  I’m keeping the access door to this space open until I can cut some ventilation slots in it. Then I mounted the new holding plate in my icebox where the old holding plate was.

I ran some 12AWG wiring from my DC breaker panel to the compressor unit and also wired the thermostat inside the icebox to the compressor.

Then I connected the two copper refrigerant tubes to the holding plate, ran them through a hole I cut in my icebox and through my hanging locker and into the compressor under my berth.  After that was done I sealed up those holes with some insulation-in-a-can. And that was it!

The most time-consuming part of this whole thing was making the shelf to put it on and running back and forth to the hardware store; the rest of it only took a couple of hours. I did need to charge it since I lost a little R-134a while connecting the tubes.


The compressor on the platform. The condenser and fan sit right in front of the storage access door to promote air circulation.

The system runs great!

Do you have any other thoughts on this system? I’ll follow up on this in a couple months or so to let you know how efficiently it’s keeping my beer cold.

Heidi Kortman

Friday 3rd of August 2012

Another step accomplished. I hope it runs without trouble for years, and you never lose the sense of satisfaction in each cool beverage.

Gary Pitsenberger

Friday 3rd of August 2012

There must be hot air coming off the compressor. How do you vent it overboard? I have long considered a Technautics unit, but $ and greater necessity have dictated other projects come first. Right now I'm considering a holding tank, as our LectraSan system has died of old age, as well as still repairing cosmetic damage inflicted by another boat while anchored out during Irene. (Our boat "Dragonfly," a Pearson 323, is presently docked at Washington Yacht Club.)

John Peltier

Friday 3rd of August 2012

The hot air vents into my cabin (gasp!). The fan blows the hot air off the condenser and out of the storage access door. However...when the temp in my icebox was 90+F, yes, it was hot air and that fan was working hard to cool the condenser. Once the temp in the icebox dropped to about 75F, the fan slowed down considerably and the air coming off the condenser seemed to be cool as heat was still being removed from the icebox. I can see how promoting free air circulation is important. Prioritizing projects is no fun, right? I still haven't walked the docks at WYCC yet but I'll look for Dragonfly when I do.