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recommendations for electric refrigerator for off-grid home  RSS feed

 
Posts: 8
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My propane fridge quit, and I'm planning to replace it with an electric fridge. I'm looking at Energy Star rated appliances but wonder what other people have found work best for them off-grid? I'm not interested in trying to keep ice in an insulated box and haven't yet heard of other cooling methods that seem really effective, but I do have a PV system in place so I think I just want to go with electric. It could be DC or AC but the main thing is that I want as large a fridge capacity as possible, so I'm looking at models without a freezer included. We have a chest freezer that runs on DC and it suits our freezer space needs fine. Any recommendations for fridges that are good on energy consumption?
 
Posts: 97
Location: 6A
13
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We're kind of doing the same thing. I haven't found much. Seems most are at least .5 kwh a day. What's your system specs?
 
pollinator
Posts: 568
Location: Southern Arizona. Zone 8b
74
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You can buy ones that run on 12V or 24V DC (SunFrost, etc.) however they cost more than buying an inverter and an Energy Star fridge.  The DC models might be slightly more efficient, but with PV panels so cheap, it's better to just buy more panels, etc.


One option that is much more efficient is to take a chest freezer and convert it to a refrigerator.  This way when you open the lid, you don't dump out all your cold air.  Of course it might be a little less convenient.  There are a lot of articles online about how to do this and a few folks even sell the controllers.
 
pollinator
Posts: 190
Location: Sask, Canada - Zone 3b
37
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I'd like to make an analogy. There were once top-fill washers only, but then it was realised that doing something as simple as putting the spinner on it's side(side-fill washers) meant that less water/electricity was used overall.

The same mistake has been made with fridges, as any fridge with a side door is a poorly designed one. There is really no need for those new "smart" Samsung/LG fridges, when all we must do is adapt the design of a freezer on to a fridge. Even though a fridge may only be opened for less than 3-5 minutes a day,  all that cooled air literally tumbles out, which means a lot more work for the fridge. Think about how Supermarkets keep food frozen in chest freezers without any tops on them.

My recommendation, for anyone up for something different, would be to convert a chest freezer into a fridge.

Here is the article by the guy who has been promoting these conversions for years. He says his "fridge" only works for 90 seconds per hour, which is part of the reason it only consumes 0.1 kwh a day.

Edit: Peter beat me to the punchline
 
Posts: 232
Location: Northern New Mexico, Latitude:35 degrees N, Elevation:6000'
11
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I have a chest freezer converted to a fridge.  You can find the controller you need on amazon.  I'm using is the, A421 Johnson Digital Controller.  Mine is actually the older version of the A421.

If I were to do it again.  I would silicone all the seams along the bottom inside before ever turning it on.  There is constantly moisture on the bottom, and those seams begin to corrode.  You'll need to set up your fridge so the water can exit the drain.  I need to find some type of flooring to put along the bottom to keep items out of the moisture, yet still allow the water to reach the exit.  The drain, I have a neighbor who mentioned that some people are putting some silicone tubing into the drain and forming a J-tube on the outside so that the moisture can always exit.  All of that extra water means that the fridge will get funky faster.  And whenever I load my fridge from a costco run, as it's cooling all the items, an ice sheet will form on the inside front wall.  The front inside wall as well as one of the ends of the fridge will freeze items that are touching it.  I need to find a spacer, I was thinking maybe insulation or some type of flooring that has big holes.

Getting items in and out can be a pain.  I still haven't tried to figure out an organizing system for the food I buy.  I keep thinking plastic crates of various sizes.

It works, but I wish I had an actual fridge that was easier to keep clean and get items out of and didn't freeze my produce that was touching the wall and didn't fill with water....and.... LOL
 
Posts: 106
Location: Pyrenees Mountains, South of France
12
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When we changed our system from 24v to 230v, we needed a new fridge.  We looked for one with no freezer and the highest economy rating of A+++ .  I don't think the make and model is all that important, they all work pretty much the same.  What we did though, is place it in the outdoor porch so that in the winter when the porch is very cold and we have less electricity, the fridge barely kicks in.
 
Posts: 197
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I had done some research on this before. This the route I'll eventually be taking.  I even though about keeping the fridge outside, perhaps under the camp or on a future back porch/ mud room when the weather cools. Also even thought about the possibility of " sinking" it into the floor ( camp will be up on reclaimed telephone poles about 5 ft).  I was also thinking about getting a larger freezer and adding 2"to 4" of insulation on the inside and adding some type of liner to catch condensation or the size freezer I need and adding insulation to the outside. Perhaps it having it have its own panel(s) and controller and batteries. So all my "eggs" are in are not in one basket. May seem a little more complicated but if something breaks, there's an extra on site. wont be able to just hop in the truck and go to Home Depot.   larry
 
pollinator
Posts: 328
Location: SoCal USA
35
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I got a used chest freezer from a coworker for $25 with the idea of either converting it to a fridge, or to store bulk purchases of on-sale food stuffs. I was thinking if a person had or made a root cellar space to place a chest fridge, that might nearly eliminate the need for power to it (depending on the soil temps of your area).

Basing this on my assumption of building either a cob house or bermed Oehler/Wofati structure, I would think you could dig in a small space that steps down 2-3 steps to where the fridge sits at an earth-stable temp year-round, and could also have several shelves for storing your harvest in that cool, dark place. Put a led light on the inside of the lid facing towards the back, and when you open the lid it will then be facing down into the chest. Rechargeable AA/AAA battery to power it should last a really long time between charging.
 
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Hey. I also encountered a similar problem.Refrigerator, TV, electric stove, lighting systems must be the most modern, economical - to have enough electricity from solar panels. This technique is not cheap. For such refrigerators it is desirable to have a pure sine. From the modified,  it will work too, but there is a risk of premature failure of the refrigerator. Sometimes the refrigerator can not start. The inverter with a modified sine for the refrigerator is bought when the budget does not allow a clean sine, they are much cheaper, for example, at 1000 watts 12V. The inverter is a pure sine at 12V , usually more than 2-3 times. Dry residue - a modified sine pulls the refrigerators.But if you have money, it will be better to buy a pure sine. https://grapefrost.com/chest-freezers/
 
pollinator
Posts: 1970
Location: Cincinnati, Ohio,Price Hill 45205
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In a perfect world i would have two identical upright freezers, one converted to run as a fridge.
For me, accessing the freezer is an everday thing,so an upright is worth it.

Someone mentioned keeping the fridge outside.
I had thought to expose the coils to winter air, but Ive been informed that the compressors in refrigerators only work in a narrow band of tempatures.😞

I have thought of a fridge as an root cellar. A thermostat controled light bulb would keep it above freezing.
 
Posts: 145
Location: MA
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This data probably isn't published separately, but one efficiency parameter is the compressor efficiency.   Another is the insulation value.  Some of the newer fridges are much more insulating than the ones of a decade ago.  If there's any way to find out that information, even just from reviews, it's probably worth knowing. 

I like the idea of using a chest freezer as a fridge simply for the efficiency advantages. 

If you're running it off solar, or any other intermittent source, or you want it to perform better in a power outage, I figure the most practical and least expensive form of energy storage is ice (as compared to say batteries).  To implement this, ideally there would be physical contact in order to form a conduction path between the evaporator coils and the ice/water storage, (although it's not strictly necessary).  Supposing that the rest of the fridge was cooled by convection, then that would be the bottleneck for heat transfer.  If the design worked out right, then it might be possible to get away with a single temperature controller cooling the air in the fridge to nominally 40 deg.F ( 5 deg.C).  Presumably then the evaporator would have to pull heat out of the ice/water before pulling heat out of the air, since there would be a lower thermal-resistance to the ice/water than to the air.  This might mean the ice/water temperature would have to drop down to freezing just to cool the air in the fridge to say 40 deg.F.  That might be a way to have below-freezing thermal storage and at the same time an above-freezing fridge while using just a single thermostat.

If the food or drinks were getting too warm or freezing, then maybe the ratio of evaporator surface area touching the air versus area touching the ice/water could be adjusted until the balance was right.  Or more simply, I suppose the thermal storage could be placed in the colder spots, and the food & drink in the warmer spots.  Then just adjust these positions and the thermostat setting until the ice packs tend to freeze but the food & drink doesn't. 
 
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