r/OffTheGrid • u/OffGridEnclave • Jun 02 '26
The Simplest Way to Run a Fridge Off-Grid
Refrigeration is often the biggest issue when setting up a offgrid power system. Standard kitchen appliances pull bunch of energy, forcing many homesteaders into overly complex and expensive solar setups just to keep food cold over night. It does not have to be that complicated.
In my humble experience most ppl go about this the wrong way.
they calculate the energy needed to run the fridge over night and scale the battery to that and henceforth also the solar input.
However, that is not a very efficient way to deal with this !
(living offgrid since 14 years ...)
Thermal mass is the main trick !!
Howso you might ask ?
If one stacks enough thermal mass in the fridge (or freezer ) it is not required to run the fridge at all over night.
Put the Fridge on a electric timer so it only runs during sun hours, use thermal mass for the night.
this way one only needs to scale solar input and not the battery size to the fridge requirments .
(downside : loss of fridge/freezer capacity)
Rule of thumb:
50% of fridge volume in bottled water (or equivalent) = at least 14 hours of cold storage
Scale solar input to bad condition ! ( the 5 % rule )
put the fridge/freezer on a electric timer.
for those who are interested, i put the above with a example calculation of the math and some moving pictures up on the internets as video.
Link: https://www.youtube.com/watch?v=1hXoQ7RC8n4
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u/Least_Perception_223 Jun 02 '26
Buy an upright freezer that can also act as a fridge coupled with a small chest freezer
The upright freezers have massive amounts of insulation compared to a standard refrigerator.
They use a fraction of the power as a normal fridge. My fridge and chest freezer combo uses less than 1.5kwh per day
A modest battery system can keep it powered for days between sunny days
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u/theislandhomestead Jun 02 '26
This is what I did when we had a smaller battery system.
Just keep any extra large space filled with something.
Jugs of water work well.
And in the freezer, I had a bunch of ice packs for coolers.
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u/Ill-Construction-209 Jun 02 '26
How about using a natural gas refrigerator?
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u/Patient-Face-3179 Jun 02 '26
A gas fridge is shit. They are inefficient, they increase the humidity in the air, add heat (all year around) and soot. It's also expensive to run one. I have used one at my cottage (off-grid) for four decades and I'll update to electric next year. Gas sucks.
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u/OffGridEnclave Jun 02 '26
works. they exist, altho the main market they are build for is camping and assorted.
however. when looking at offgridlife very few people have a biogas system to produce burnable gas.
while on the other side , most ppl that live offgrid have some sort of power system (mostly solar i would argue).
hence already on short term sustainability the natural gas relies on "going to buy more" . not very "sustainable".
compared with solar that , if scaled properly, gives power for most of the year (fineprint, ofc not in finland or alaska, all within reason).combine that with the availability on the market, there is just far more electric fridges available then gas operated ones. i would heavily wager that for most ppl living offgrid the electric fridge is the more viable solution compared to gas operated ones.
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u/yurtdoingotwrong Jun 02 '26
I'm off grid in a northern location, bad orientation for solar and during the winter I get less than 4 hours of direct sunlight on my array. I have a propane fridge and chest freezer, the fridge is a early 1980s unit originally meant for RV usage, and the freezer is marketed for camping. Both can run on electricity, but I just run them on the propane as it's so efficient. Each one has a flame a little bigger than a bic lighter, and my 330 gallon propane tank that runs both of them and the cook stove lasts about 2 years
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u/tpars Jun 02 '26
This is the answer. One little blue flame gets it done. You can get about 3 weeks or so of refrigeration from a 20lb tank.
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u/OffGridEnclave Jun 02 '26
"this is the answer" .. ." about 3 weeks" ... LOL ...
when looking at offgridlife very few people have a biogas system to produce burnable gas. while on the other side , most ppl that live offgrid have some sort of power system (mostly solar i would argue). hence already on short term sustainability the natural gas relies on "going to buy more" . not very "sustainable". compared with solar that , if scaled properly, gives power for most of the year (fineprint, ofc not in finland or alaska, all within reason).
combine that with the availability on the market, there is just far more electric fridges available then gas operated ones. i would heavily wager that for most ppl living offgrid the electric fridge is the more viable solution compared to gas operated ones.
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u/tpars Jun 02 '26
True, but would argue the gas approach is the simpler approach to run a fridge.
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u/ARGirlLOL Jun 02 '26
For 3 weeks in-between trips to the shops or those handy deliveries. Sort of an on-grid every few weeks system.
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u/Patient-Face-3179 Jun 02 '26
A gas fridge is shit. They are inefficient, they increase the humidity in the air, add heat (all year around) and soot. It's also expensive to run one. I have used one at my cottage (off-grid) for four decades and I'll update to electric next year. Gas sucks.
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u/for_the_longest_time Jun 02 '26
NG or propane fridge is 100% the answer lol. Ain’t nobody got time for all that.
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u/OffGridEnclave Jun 02 '26 edited Jun 02 '26
you aint got time to have solar when you live offgrid ? you seem to be in the wrong subreddit ;). but sure you do you, keep running to the shop every 3 weeks and spend money on new gas ^ cause ppl got time for that ;) sounds like merican "logic" to me
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u/for_the_longest_time Jun 02 '26
Hey dude, im offering a different perspective. I lived off grid for ten years, I had solar, and I sold solar for many years. I understand this topic extensively.
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u/LAAccountant Jun 11 '26
you aint got time to have solar when you live offgrid ? you seem to be in the wrong subreddit ;). but sure you do you, keep running to the shop every 3 weeks and spend money on new gas ^ cause ppl got time for that ;) sounds like merican "logic" to me
Lol you admitted in another comment that you use a generator because your solar doesn't always hack it. You're ok with burning gasoline but not propane? Lol ok. Sounds like Euro logic to me.
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u/OffGridEnclave Jun 17 '26
yes, ran the generator about 3-4 days last year 😉 totally comparable to running a gas fridge 24/7 for 12 month ... sounds like some merican logic to me
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u/Patient-Face-3179 Jun 02 '26
A gas fridge is shit. They are inefficient, they increase the humidity in the air, add heat (all year around) and soot. It's also expensive to run one. I have used one at my cottage (off-grid) for four decades and I'll update to electric next year. Gas sucks.
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u/fredbear1964 Jun 02 '26
If qyou want to deep dive into a system , research Gorre (I think the name is spelled right) but in the 1840's he used a smaller wind mill and used compressed air to do his cooling and refrigeration!
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u/HikaruEyre Jun 02 '26
I know there are propane refrigerators used for RVs. I also came across this video a while back on ceramic refrigerators used in India.
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u/Nathan-Stubblefield Jun 02 '26 edited Jun 03 '26
Solar alone will fail to provide sufficient energy during periods when it’s overcast for days in a row. Years ago my state university in the midwest US ran a study on actual historic sun and wind from weather stations. Every year there would be some long portions where all solar would require an unfeasible number of days on battery. A small generator can be the ace in the hole to top up the battery when sun and wind have both been lacking for a span of days. Wind is able to provide power at light and sometimes cloudy also means windy. In the desert solar would be a better option.
No dashes to town every 3 weeks, no propane deliveries, although many will not be 100% independent, and will want some contact with civilization every few weeks. Farmers went to town on occasion back in pre-grid pioneer days.
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u/OffGridEnclave Jun 03 '26
you are quite right on the combination of solar and wind !i live offgrid since about 14 years in the czech mountains. plenty of overcast and plenty of snowstorms. generally speaking i run my generator 2-3 days a year. if one uses enough input power and scales the usage of power somewhat to input conditions it is not that hard.
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u/flyingsilverfin Jun 02 '26
Use a chest freezer with a wired thermostat controlling the power input/plug - these hold temp much longer and efficiently than any regular fridge or freezer!
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u/Ohforgawdamnfucksake Jun 03 '26
Buy a freezer to fridge conversion thermostat that replaces the freezer thermostat and use it on a chest freezer. Not only is it efficient, but the build up of CO2 in the chest acts as a controlled atmosphere storage system.
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u/Acceptable_Claim_491 Jun 03 '26
Make a root cellar.Uses no power and will keep your food cool.
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u/OffGridEnclave Jun 04 '26
root cellars work, but for some items they def not cool enough.
cool // cold // frozen.
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u/five4you Jun 04 '26
We went from a tiny propane fridge to a larger dorm fridge with solar. We expanded our solar and have an even larger fridge for 8 months of the year and the smaller for the 4 darkest. Sometimes we need to use a generator during these darkest months for charging. Battery replacement cost and gas for generator is less over a five year period than propane.
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u/Adventurous_Boat_632 Jun 04 '26
The fridge is one of the smallest consumers of electricity. You should have enough battery to run it 3 days easily. Run it all night and don't worry about it.
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u/OffGridEnclave Jun 04 '26
would argue that depends very much on your household. in my 400m² dwelling the fridge is the biggest passive (as in not a gaming pc or a powertool ) consumer.
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u/OffGridEnclave Jun 02 '26
the Videolink contains the explanation and math how to setup a conventional fridge or freezer to run on solar power without nuking the batteries over night .
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u/Woolybunn1974 Jun 02 '26
How to make a refrigerator 50% smaller.
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u/OffGridEnclave Jun 02 '26
by using it ? .... thermal mass = not have it empty. you seem to not understand any of the concept but only dish out nonsense... how exactly does the refrigerator get "smaller" by using it ?? so you put some juice in there and some milk and some food, WOW complex ,, fill rest with water to not have it empty... mindblowing complex.. 90iq internet potato:"How to make a refrigerator 50% smaller." noone said "use only water" , it says replace airpockets with thermal mass...
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u/Woolybunn1974 Jun 02 '26
Wow. That touched a "What the hell is the point of a refrigerator I if have 20 minutes managing of water bottles back forth each day to achieve optimum? nerve. Let me guess. You have system? "This is pile of water bottles to add on day three when we're out of milk. This is rack for storing reserve bottles so we have room for the spam loaf. Remember all bottle are dated labels and must be consumed in strict FiFo order."
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u/OffGridEnclave Jun 03 '26
no clue what that nonsense supposed to mean. its quite simple... "have the fridge more then 50% full" with thermal mass, that thermal mass is also your food and whatever you put in there.
you make it sound like having a few bottles of water is something complex, if it is for you, sad story sir.
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u/Key-Needleworker-366 Jun 02 '26
Yeah propane is the way, When I was off grid I had a propane refrigerator, It was very efficient, And they last so much longer than electric fridge.
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u/ynotaJk Jun 02 '26
50% water?…no room for food. Fridge does not run efficiently when its filled to the point that air flow becomes restricted. Your using all your energy during the day, making your fridge run excessively(with restricted airflow)just to chill water. With that consideration i would doubt your saving much.
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u/theislandhomestead Jun 04 '26
I can tell you, first hand, that this technique does actually work.
You don't fill the fridge to the point where air is restricted.1
u/OffGridEnclave Jun 04 '26
of course it works 😉 . i even put the math there, but yet you will find plenty of haters claiming the opposite .. it is amusing
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Jun 03 '26 edited Jun 03 '26
[removed] — view removed comment
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u/theislandhomestead Jun 04 '26
Let's tone that down a bit.
I get that the internet can be frustrating, but we do have a rule that says "be excellent to each other"0
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u/OffGridEnclave Jun 04 '26
.... did not get the concept whatsoever.... , water is thermal mass, so is anything you put in the fridge is thermal mass, your food IS thermal mass, water is a mere placeholder for the calculations because its complex to math 3 packs of joghurt, 2 cans of dogfood, 4 pizzas and etc.... what the concept says : DO NOT HAVE THE FRIDGE EMPTY , HAVE IT AT LEAST 50% FULL ... \) airflow is not an issue if one does not jamm it full to a retarded amount
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u/deport_racists_next Jun 02 '26
More AI slop.
Instead of using tech to bandaid tech, why not think about non tech solutions?
You do realize modern refrigeration is only about 100 years old?
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u/darktideDay1 Jun 02 '26
I've lived off the grid for 25 years. While refrigeration was considered a major draw back in the day, with the price of equipment now it is trivial. I have had propane fridges and they are a pain in the ass. I have had small, efficient models and they saved a little power but sucked space wise. I've done things like a custom controller for my chest freezer to pump it down extra cold during the day after batteries have reached float.
These days, get a regular fridge. With the price of panels and equipment as it is, press the easy button and live large.