Fridge on off grid system.

microage97
microage97 Registered Users Posts: 12
Hello all,

I am trying to figure out how to account for a AC powered fridge into my design. Say the fridge uses 1,000 / day. I know there will be a start surge.....

I am going for a 24V bank of 8 GC batteries and trying to figure out what size inverter I will need....

Thoughts?

Sorry for the noob question.

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Fridge on off grid system.

    Welcome to the forum.

    That's a perfectly normal question. The answer is, unfortunately, "it varies".

    What you have is 1,000 Watt hours per day; a quantity of consumption. Not unrealistic either as a standard refrigerator will run about that much +/- and with variation depending on temperature conditions and usage.

    How much it demands on start-up is another matter. The surge is momentary, but can be 5X the running current - or even worse. Without an expensive current meter to measure the actual surge you can only guess. In most cases a quality inverter around 1kW will start a refrigerator, although any additional loads have to be taken into account.

    If you think about the capacity of a single 15 Amp 120 VAC circuit (known to be able to power a refrigerator) that's 1800 Watts. So basically you should be looking at inverters that run between 1kW and 2kW.

    There's quite a few exceptions to the rule-of-thumb though.

    Eight GC2's would be 440 Amp hours @ 24 Volts - plenty of power for running a refrigerator and quite a few other things.
  • microage97
    microage97 Registered Users Posts: 12
    Re: Fridge on off grid system.

    Thanks Cariboocoot!
  • oil pan 4
    oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    Re: Fridge on off grid system.

    A normal fridge like mine, a full sized unit, uses around 350 when running usually consumes around 1kwh per day.
    Have you thought about converting a deep freeze to a fridge? Freezer converts use ridiculously low amounts of power, some where around 0.25 to 0.35 kwh per day.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • microage97
    microage97 Registered Users Posts: 12
    Re: Fridge on off grid system.
    oil pan 4 wrote: »
    A normal fridge like mine, a full sized unit, uses around 350 when running usually consumes around 1kwh per day.
    Have you thought about converting a deep freeze to a fridge? Freezer converts use ridiculously low amounts of power, some where around 0.25 to 0.35 kwh per day.

    That might be a possibility in the future. I just don't have the time as I need to have a working system as possible in 90 days. I will keep that in mind for the near future. Thanks Oil Pan!
  • oil pan 4
    oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    Re: Fridge on off grid system.

    You could do it in the amount of time it takes to ship the $20 or $30 worth of ebay parts to your door.
    Cool thing about it is you don't have to modify the deep freeze beyond taping a thermo sensor to the inside of the freezer. Other wise the "mod" is 100% external. I almost did it when our old fridge unexpectedly quit last year, but my girl said she wanted a real fridge.

    You can usually find used deep freezers for dirt cheap.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • microage97
    microage97 Registered Users Posts: 12
    Re: Fridge on off grid system.
    oil pan 4 wrote: »
    You could do it in the amount of time it takes to ship the $20 or $30 worth of ebay parts to your door.
    Cool thing about it is you don't have to modify the deep freeze beyond taping a thermo sensor to the inside of the freezer. Other wise the "mod" is 100% external. I almost did it when our old fridge unexpectedly quit last year, but my girl said she wanted a real fridge.

    You can usually find used deep freezers for dirt cheap.

    Yup I hear you. It is just that I literately will soon be moving and build our home at the same time and then there is the Wife who wants something "normal" Certainly I will consider it for our next or additional fridge.