First a disclaimer…this refrigeration unit does not run directly from my solar panels. It runs off of my batteries, which are recharged by the sun, and I’m going to mostly run this unit only when the sun is out, so…ipso facto, a solar-powered refrigeration unit. There are a lot of sailboat refrigeration systems out there, and this is why I chose what I did.
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.
Technautics Cool Blue
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. And also as with everything I do, I’m right. Kidding…but I do have some valid reasons.
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. I can understand it for weekend outings, but not as a permanent solution.
I also chose a holding plate over a standard refrigerator evaporator plate because evaporator plates cycle off and on dozens of times a day. They do maintain a near-constant temperature, where the holding plate system, only cycling a few times a day, has a more variable temperature range. The Technautics refrigeration system does have a thermostat, and I may use it or I may just manually cycle power to the unit when I need to.
You may 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 system for someone like me who won’t be using it every single day – only when I have food in my stores that will spoil – and wants an efficient system for when it does run.
My engine-driven system took up a lot of room, with the compressor & belt from the engine, seawater condenser, and 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 hole in my hull (fight that urge!). 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, then I told myself that I’m only running this during the day, hopefully when the sun is on my 50W (soon to be 100W) 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. 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. Then I sealed up those holes I cut 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 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.