Fridge/freezer power use vs. 2 chest freezers

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  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    Re: Fridge/freezer power use vs. 2 chest freezers
    BB. wrote: »
    While I like the idea of running without a battery--There is real issues with cycling refrigerator and freezer temperatures (warmer food does not last as long, temperature cycling increases chances of freezer burn . . .

    There are a few dedicated solar refrigerators out now intended for vaccine usage; they use eutetic salts that freeze and maintain temperature for several days with no power. They are hideously expensive, but using a similar system (salts in a bag in your refrigerator?) you could greatly decrease temperature variations.
  • vtmapsvtmaps Solar Expert Posts: 3,739 ✭✭✭✭
    Re: Fridge/freezer power use vs. 2 chest freezers
    There are a few dedicated solar refrigerators out now intended for vaccine usage; they use eutetic salts that freeze and maintain temperature for several days with no power. They are hideously expensive, but using a similar system (salts in a bag in your refrigerator?) you could greatly decrease temperature variations.

    more here:
    http://forum.solar-electric.com/showthread.php?p=175235#post175235
    and here:
    http://forum.solar-electric.com/showthread.php?4860

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • StdyhandStdyhand Solar Expert Posts: 33
    Re: Fridge/freezer power use vs. 2 chest freezers

    What size inverter would be needed to run two 110v deep freezes, both being 5 cu ft? I would likely run the freezers and a few other small things on a TSW inverter and leave some things on a MSW unless I find a TSW large enough and within a reasonable price range.
  • BB.BB. Super Moderators, Administrators Posts: 31,903 admin
    Re: Fridge/freezer power use vs. 2 chest freezers

    In theory, you probably need ~1,500 watt AC inverter to start a second freezer when the first one is already running.

    There is always the possibility that both would start at the same time, and you are looking at a ~2,400 watt inverter to do that--Or setup a relay (a bit of a detailed discussion on how to do that) to prevent both starting/running at the same time (one poster here did that on his small system).

    Are you looking to run two freezers or one freezer + one as a refrigerator? Efficiency wise, it is almost always more efficient/less costly to run one larger freezer vs two smaller freezers. Volume goes up with the cube of the size of the freezer, square footage of the surface area goes up with the square of the size... So there is less heat loss through walls per cuft of volume as the units get physically bigger.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • StdyhandStdyhand Solar Expert Posts: 33
    Re: Fridge/freezer power use vs. 2 chest freezers
    BB. wrote: »
    In theory, you probably need ~1,500 watt AC inverter to start a second freezer when the first one is already running.

    There is always the possibility that both would start at the same time, and you are looking at a ~2,400 watt inverter to do that--Or setup a relay (a bit of a detailed discussion on how to do that) to prevent both starting/running at the same time (one poster here did that on his small system).

    Are you looking to run two freezers or one freezer + one as a refrigerator? Efficiency wise, it is almost always more efficient/less costly to run one larger freezer vs two smaller freezers. Volume goes up with the cube of the size of the freezer, square footage of the surface area goes up with the square of the size... So there is less heat loss through walls per cuft of volume as the units get physically bigger.

    -Bill
    I was planning to run two 5 cu ft freezers since that is all the space I would normally need before another visit to the store. I wish I could use one larger freezer and just use a small area of it as a fridge but I haven't found anyway to do that. I keep very little in my fridge anyway, mostly just things like dairy products. As for the inverter, that is about what I expected. A TSW inverter to power both may cost a bit much so I may just go ahead and run them on a MSW. I've read they may run a little warmer but due to where they will be put that shouldn't be much of an issue. If they don't last as long at least I can easily pick up another close by.
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