D C refrigeration

There appears to be some reasonably (realitive to otherenergy efficient brands) priced DC refrigerator/freezers on the market by Sundanzer. Could these appliances be attached to some sort of "inverter" to run off AC and would that still result in substantial energy efficiency?
Tom

Comments

  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    The best way to use stored DC electricity is to convert it to AC via the DC to AC inverter. This component is the most important in a system because it allows the use of readily availiable appliances and lighting fixtures that use AC .Buying all DC appliances will be expensive if not impossible to do.
    My Outback power conversion equipment enabled me to construct a back up power system using solar and wind energy ( DC sources) to charge batteries and switch from grid power automatically in the event of a power failure.

    Chuck K
  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    Appreciate the advice, Chuck .  It appears it is best to stick to AC appliances. Sunfrost seems quite expensive although I am sure it is worth every penny of  its cost. Is there any less costly  alternatives?
    Tom
  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    Beowulf,

    The using a chest freezer as a refrigerator from this thread:

    http://www.wind-sun.com/smf/index.php?PHPSESSID=8374c031bedaa27dab793febdb1dd317&topic=1073.0

    is probably a really good starting point. Cheap to buy, cheap to run. Possibly put an extra muffin fan in the refrigerator (that turns on with the compressor) to stir the air would be a nice addition.

    Looking at the sunfrost web site, it appears that their 19 cuft units are roughly as efficient as a cheap chest freezer (or converted chest refridgerator) to operate.

    It really depends on your choice if you would rather use an upright or chest model... Modern AC fridge/freezers are pretty darn efficient now-a-days.

    Going with a DC system would probably only be an advantage if you are off grid or something like that.

    -Bill
  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    as this list shows the sunfrosts are WAY more efficient, but i dont have $2500 for a fridge!
    im not sure if its all the insulation, electronics or what but its remarkable and clearly designed for iffgrid use where low power is a must.

    http://www.aceee.org/consumerguide/topfridge.htm

    our fridge is a frigidaire gs18 that is energy star and rated at max 430kwh's per yr. thats a small fridge.
    heres a better list, with kwh ratings:
    http://www.energystar.gov/index.cfm?fuseaction=refrig.display_products_html
  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    It is hard to tell from the various sites about what is the comparitive numbers between Sunfrost and other brands...

    Looking at a Sunfrost 19 cuft refrigerator/freezer uses between 0.77kWh/day (70F) and 1.02 kWh/day (90F). That works out to 281 to 372 kWhrs/year.

    From your link a 18 cu.ft. refrigerator/freezer runs around 387 to 405 kWhrs / year. Given that we don't know how the rating systems actually compare (are the energy star ratings at 70F or some range or what?). However, these ratings are pretty close and would only result in approximately in $3-$20 per year difference in costs... Even after 10-20 years, you would not even come close to saving enough money to make up the price difference.

    The thread I pointed you to, the wind-sun member was currently averaging ~0.240 kWh/day (~70F) for a "Chest Refrigerator". That compares pretty favorably with the SunFrost R19 (fridge only) at 0.33 kWhrs/day. "Jay's" freezer is only a 7 cuft model (and not even the most efficient). The R10 from SunFrost is rated at 0.17 kWhr/day (70F).

    So, the Sunfrosts are certainly more efficient, but comparing a R10 with a “W-S7” model, you are saving only 25 kWhrs/year. Only a couple of dollars a year.

    This should not make a big difference to someone that is grid powered and can use a chest refrigerator--But for someone that is off-grid (and/or has high air-conditioning costs) may find these energy usage differences to be very useful in reducing Solar capacity costs or in generator sizing/fuel costs.

    -Bill
  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    i have a 12 freezer and it stop freezing it only chill thing.
    sun danzer DCF225
    IT work just fine since i bought it on 7/25/2005.
    any help would be great.
    thanks :?
  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    If I understand you correctly, your freezer is just over one year old, it used to work great, but now it just chills things and will not freeze.
    If this is right, the two most likely causes would be:
    1) Most likely the refrigerant gas has leaked out of the sealed system.
    2) A fault with the compressor. This is not so likely, because if it is chilling things, the compressor is running, but if there is a short circut in the windings, this could cause the motor to appear to run OK, but get very hot and keep shutting down to cool off. A remote third cause would be a fault with the thermostat, shutting the compressor down too early. If the compressor is running continuously, the problem is likely that the gas has leaked out.

    I would contact the people you got it from. The sealed system SHOULD be covered by warranty.
    I'm not familiar with the Sun Danzer warranty, but almost any brand, including the cheep, no name ones usually have at least a 5 year warranty on the sealed system.
    Good luck
    Wayne
  • BB.BB. Super Moderators, Administrators Posts: 31,337 admin
    Re: D C refrigeration

    From Sundanzer manual:
    SUNDANZER REFRIGERATION WARRANTS, TO THE ORIGINAL OWNER, THAT THIS PRODUCT IS FREE FROM
    DEFECTS IN WORKMANSHIP AND MATERIAL FOR A PERIOD OF ONE YEAR FROM THE PURCHASE DATE.
    THIS
    WARRANTY SHALL BE LIMITED TO REPAIRING OR REPLACING, AT SUNDANZER’S OPTION AND WITHOUT
    CHARGE TO THE PURCHASER, DEFECTIVE COMPONENTS. ALL WARRANTY WORK SHALL BE PERFORMED AT A
    SUNDANZER APPROVED FACILITY. SHIPPING CHARGES RELATED TO RETURNING THE PRODUCT TO THE
    SUNDANZER FACILITY ARE NOT COVERED UNDER THIS WARRANTY. HOWEVER, THIS WARRANTY COVERS
    SHIPPING CHARGES RELATED TO RETURNING THE REPAIRED PRODUCT TO THE CUSTOMER WITHIN THE
    CONTINENTAL UNITED STATES. OUTSIDE THE CONTINENTAL UNITED STATES, ALL SHIPPING CHARGES ARE
    THE RESPONSIBILITY OF THE CUSTOMER AND ARE NOT COVERED BY THIS WARRANTY. THIS WARRANTY DOES
    NOT APPLY TO DAMAGE OR WEAR TO THE PRODUCT CAUSED BY ACCIDENT, ABUSE, MISUSE, NEGLECT,
    UNAUTHORIZED ALTERATION OR REPAIR, OR IF THE PRODUCT WAS NOT INSTALLED IN ACCORDANCE WITH
    SUNDANZER PRINTED INSTALLATION AND OPERATING INSTRUCTIONS. TO OBTAIN SERVICE UNDER THIS
    WARRANTY, THE DEFECTIVE PRODUCT MUST BE RETURNED TO SUNDANZER TOGETHER WITH A RETURN
    MATERIAL AUTHORIZATION (RMA) NUMBER. ANY PRODUCT REPAIRED OR REPLACED UNDER THIS WARRANTY
    WILL BE WARRANTED FOR THE BALANCE OF THE WARRANTY PERIOD WITH RESPECT TO THE ORIGINAL
    PURCHASED PRODUCT. SUNDANZER REFRIGERATION WILL NOT BE LIABLE FOR ANY INCIDENTAL OR
    CONSEQUENTIAL DAMAGES, LOSSES, OR EXPENSES ARISING FROM INSTALLATION, USE OR ANY OTHER
    CAUSES. THERE ARE NO EXPRESS OR IMPLIED WARRANTIES, INCLUDING MERCHANTABILITY OR FITNESS FOR
    A PARTICULAR PURPOSE, WHICH EXTEND BEYOND THOSE WARRANTIES DESCRIBED OR REFERRED TO ABOVE.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: D C refrigeration

    :-( OUCH!!! Looks like no extended warranty on the "sealed system".
    Therefore, that's a brand I would now stay away from.
    And all those shipping charges? If you live outside USA, what do you do, shove it over the fence, into the neighbor's yard at three in the morning and hope he doesn't have a dog?
    Wayne
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