off grid refrigerators...what do you use..?

cupcakecupcake Solar Expert Posts: 254 ✭✭✭
Hi pals,

I'm soliciting low watt fridge suggestions...
Efficiency (low watts) matters more to me than size...

Please post your personal recommendations and fridge specifications if you have them...


~1.5Kw PV in parallel
Morningstar MPPT-60 controllers (2) in parallel
3 Trojan tr-1275's in parallel 450ah total
Samlex 2,000 watt 12-volt inverter hardwired


  • BB.BB. Super Moderators, Administrators Posts: 30,055 admin
    Re: off grid refrigerators...what do you use..?

    Size does matter...

    It is really a mixed bag out there... A small "bar/dorm" 2 cuft refrigerator may use 270 kWH per year.

    A 33 cuft LG refrigerator/freezer with ice/frost free/etc. may use 550 kWH per year.

    On a per cuft basis--The larger refrigerator (with all the bells and whistles) is much more energy efficient. And probably requires the same size AC inverter as the small mini fridge (both probably need 500-600 Watts minimum to start.

    And interesting method to make a very low power usage refrigerator is to get a 7 cuft or larger chest freezer and do a thermostat-ectomy... Replace the freezer thermostat with a refrigerator version. There have been reports of folks getting down to 0.250 kWH per day with such an installation (~91 kWH per year).

    Auto-defrost/frost free refrigerator/freezers generally have a timer on them and need a 24x7 AC power source (inverter always on). The defrost timer needs to defrost around every 12 hours--And some newer refrigerators with electronic timers will start a defrost cycle when the AC power is restored.

    The "simple" manual defrost (or chest freezer conversions) tend to work better with inverters that have "sleep mode" than the "high tech" appliances (no defrost timers to mess up).

    You can get "off grid" freezers with compressors that will run directly from 12-24 VDC battery banks--Or even from solar panels (cool during the day, coast at night). But these guys tend to be very pricey.

    Then there are the RV Refrigerators... Those with Ammonia Absorption cycle (propane flame, some with backup 12vdc/120vac) that are nice for seasonal/weekend cabin use. But are not recommended to run from solar/batteries (they are usually energy hogs when running electric power to replace the heat from a propane flame).

    And there are RV refrigerators that have DC compressors (like the off grid refrigerators)--That run more efficiently from DC/solar power.

    So--Start with what you need (cuft, refrigerator or refrigerator/freezer, weekend/seasonal or 9+ months off grid, etc.). Then see what will meet those needs.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: off grid refrigerators...what do you use..?

    I've been using converted freezers, both chest type and upright for 10 years, with great energy success. The present one, an upright 10 cuFt uses roughly 0.2 kw/24 hour day when run at just barely over the freezing point. The first one, a 5 CuFt chest, is still in use at my cousin's off grid cabin in the back woods. It uses roughly the same, 0.2 kw/24 hour day.
    The downside? Especially in humid weather, there can be a buildup of moisture which must be drained off or otherwise removed, but you get used to it. The upsides outweigh the downsides. Vegies last like in no other fridge I've ever seen, and I'm no spring chicken! And running them at near the freezing point results in items lasting far beyond anything in standard fridges. The pluses are so great over a standard fridge that even considering the occasional moisture buildup, I'd never be happy with a regular fridge again.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: off grid refrigerators...what do you use..?

    I have this weird way of doing it: choose refrigerator to fit needs, size power system to run it.
  • stmarstmar Solar Expert Posts: 361 ✭✭✭
    Re: off grid refrigerators...what do you use..?

    I am grid tied but I have a Sun Frost RF-16 24vdc as our main frig. It has been running for over 15 years with no problem, supposedly the top mounted condensers are the longevity key. They are pricey and it was here when I bought the house.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: off grid refrigerators...what do you use..?

    There are several brands of "low energy" fridges and freezers, most from scandinavia. eg gram, vestfrost, elcold. These all have thicker insulation. While attractive in theory, youll want to do your homework before going this route. The payback from decreased energy consumption may not be enough to offset their extra initial cost.

    Scandinavia does however make some great whiteware. We have had an asko washer that didnt miss a beat in nearly 20 years. Build quality is unforunately something that is hard to get information on, and usually after the fact.

    Id be taking a look at the energy star stats eg:

    Notice samsung have some really up there products in terms of kWh/yr. Then shop around and see whats a good deal. I tend to prefer glass/rack shelves, the nasty plastic things you see these days are better avoided.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,

  • chevensteinchevenstein Solar Expert Posts: 100 ✭✭
    Re: off grid refrigerators...what do you use..?

    I have one of these:

    It doesn't use too much propane, it will make ice in the fridge section if you let it, and it's gigantic. I also like being able to turn my inverter completely off if I go away for a few days or a week and not having food spoil. It is also about the only part of my off grid living situation that has been trouble free for the entire four years I have been out here. The only drawback is the high initial cost. This particular model is actually a normal fridge with the guts removed and the sealed ammonia system bolted in from the back. The interior light is battery powered, but in a fit of irony I rewired it to use a 40 watt 120V incandescent bulb.

    EDIT: Now that I reread this, I do recall having the relight the pilot once. To this day I don't know why it went out on its own, but the thermocouple functioned correctly shutting off the gas and preventing me from being blown into next week.
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: off grid refrigerators...what do you use..?
    ... a 40 watt 120V incandescent bulb.

    Try one of the led appliance bulbs! costs more but...

    uses way less power
    doesn't generate heat
    looks cool when you open the fridge door

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