16.9 cu. ft. fridge uses 472 kWh/year. Economic to replace soon?

softdownsoftdown Solar Expert Posts: 3,494 ✭✭✭✭
Built in 2008 but not used until spring 2015. Nice enough Samsung fridge but it seems like one could do significantly better on energy usage these days. Or is that still a pretty good number for 16.9 cu. ft.? I'm almost 6'5", small short fridges feel odd to me. Though one could be placed on a stand.

Have a separate freezer so all I really need is the fridge. Don't know how much energy the freezer uses yet  but it has to be substantial. Thats OK for the freezer, I like to have plenty of frozen food. Some of you know that I am a prepper. 
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries

Comments

  • softdownsoftdown Solar Expert Posts: 3,494 ✭✭✭✭
    My debatable math suggests this would average about $57/year if grid powered. If battery power cost four times as much, and it probably does, that is slightly over $200/year. Yet it still appears that it would take a long time for a replacement refrigerator to pay for itself unless the size was much smaller. Am I wrong?  
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 31,161 admin
    The EnergyStar website has lots of different models--And a search by size and feature:

    https://www.energystar.gov/products/appliances/refrigerators

    Say you can get down towards 1,000 WH per day / 365 kWH per year for a fridge... What will that save you in energy (off grid power system sizing) vs the cost of a new fridge.

    At an expensive $0.30 per kWH (California prices):
    • 472 kWH per year - 365 kWH per year = 107 kWH per year savings
    • 107 kWH per year * $0.30 per kWH = $32.10 per year "savings"
    Not a lot of savings... What is the cost of a new fridge, can you sell the almost new old stock fridge, etc.?

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,494 ✭✭✭✭
    BB. said:
    The EnergyStar website has lots of different models--And a search by size and feature:

    https://www.energystar.gov/products/appliances/refrigerators

    Say you can get down towards 1,000 WH per day / 365 kWH per year for a fridge... What will that save you in energy (off grid power system sizing) vs the cost of a new fridge.

    At an expensive $0.30 per kWH (California prices):
    • 472 kWH per year - 365 kWH per year = 107 kWH per year savings
    • 107 kWH per year * $0.30 per kWH = $32.10 per year "savings"
    Not a lot of savings... What is the cost of a new fridge, can you sell the almost new old stock fridge, etc.?

    -Bill

    There is not a worse location for selling stuff. I'd be lucky to get $150 for it on top of all the other issues. But it is good to have run the numbers on this I think. Perhaps I should bump the temp back up to 40F from 38F. Wonder what that might do. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • mcgivormcgivor Solar Expert Posts: 3,605 ✭✭✭✭✭✭
    Thermostats have a throttling range which cycle the compressor, the differential can be as much as a few degrees, setting at 40°F could mean the temperature is actually above the setpoint. Inverter type refrigerators are able to maintain a more stable temperature by running the compressor at reduced speed to maintain the setpoint more accurately.

    The energy savings  would likely be minimal but the potential for product within going bad would increase dramatically.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • BB.BB. Super Moderators, Administrators Posts: 31,161 admin
    Kill-a-Watt type meter to measure your true power usage... If the environment is variable (not a 72F heated/AC space), then it will probably be a bit more difficult to see "small" changes in power usage.

    I tend towards running the fridge at 36F or so (lower tends to freeze some items in my cheap fridge)... The savings in spoiled food/ability to purchase food on sale (my wife likes that)--Probably worth more than the energy savings.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Marc KurthMarc Kurth Solar Expert Posts: 833 ✭✭✭✭
    edited October 2019 #7
    BB. said:

    [snip]...................................... The savings in spoiled food/ability to purchase food on sale (my wife likes that)--Probably worth more than the energy savings.

    -Bill

    Yes, Sir - I agree. When we bought this house a little less than two years ago, there were already two refrigerators (from 2004 and 2006) and a chest freezer in place. We already had a newer refrigerator and chest freezer that we liked. During the process of deciding what to do with the extras, we quickly realized that at $0.095/KWH, the extra power consumption is more than worth it for us for bulk food storage. We gave away the oldest refrigerator to a needy family and the rest are running.
    While we are not in a remote location, a quick trip to a sizable grocery store or Walmart, is 30 minutes each way and Costco is an hour and a half away. 
    A pair of Honda e2000i's provide more than enough power to support them. During a 12 hour power outage, I maintained them with one of the Honda's, by rotating (time sharing) power between them.  
    Marc
    I always have more questions than answers. That's the nature of life.
  • softdownsoftdown Solar Expert Posts: 3,494 ✭✭✭✭
    BB. said:
    Kill-a-Watt type meter to measure your true power usage... If the environment is variable (not a 72F heated/AC space), then it will probably be a bit more difficult to see "small" changes in power usage.

    I tend towards running the fridge at 36F or so (lower tends to freeze some items in my cheap fridge)... The savings in spoiled food/ability to purchase food on sale (my wife likes that)--Probably worth more than the energy savings.

    -Bill
    Used to be that cheap fridges seemed to be in almost all homes, I was raised middle class. Costco quit selling any cheap fridges years ago and I wondered why. Checked Amazon for a similar unit to what was previously carried. Bad reviews - a number of grossly premature failures. Failures in less than two years. Losing all that food is expensive, once lost an elk that way. 

    The advent of super cheap, failure prone, Chinese parts makes aware buying much more important than it used to be. 

    Sometimes I wonder about wrapping fridges and freezes with a few inches of quality foam insulation. Then turning them off during the night. The energy savings would be immense. A safer experiment would involve turning up the temperature setting at night then back down in the morning. But who wants to do that twice/day? Might prove wise in the proper weather scenarios however. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 31,161 admin
    edited October 2019 #9
    Insulating outside of fridge/freezer... The usual warning, in my area, the refrigerators tend to use an external condenser. But freezers tended to use condensers under the skin of the freezers--So extra insulation was a big no-no. The other major issue I saw as water/ice collected under the extra insulation, and cause corrosion and more heat losses (big ball of ice on back of deep freeze).

    I do not think that turning power off at night really saves much, if any energy... The compressor simply runs longer the next day to bring temperatures back down to setpoint (in my humble opinion).

    And, I don't like to cycle the temperature of the food in the fridge or freezer... Letting the food "warm" overnight, then running compressor "hard" for a few hours, that causes the food to "sweat" or in the case of a freezer, causes freezer burn as the water leaves the food and collects on the plastic bag as ice (or on the evaporator in the fridge/freezer).

    Years ago, I did try an AC timer on our long term storage fridge/freezers (where not opened very often)... I am on a Time of Use plan with my utility company. So, if I turn off my loads (something like 3-9pm in the summer), I would (today) avoid ~$0.39 per kWH and "make up" using ~$0.28 per kWH... In this case, I can save money.

    And there is the real issue of long term freezing >0F. (even 5F or 10F seriously degraded the food quality).. 

    https://forum.solar-electric.com/discussion/302/question-best-freezer-temperature

    Note, here is the updated link to the article (still only first page, but more details on tests):

    https://pubs.acs.org/doi/pdf/10.1021/ie50464a017

    In the end, it simply was not worth it to me.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 31,161 admin
    I found a free PDF download of the report on Zero F storage. I have attached the file to this post:

    https://forum.solar-electric.com/discussion/comment/403789#Comment_403789

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,494 ✭✭✭✭
    Mathematically logical but overlooks the off gridders worst nightmare - going to sleep with low battery voltage, likely due to bad weather, and waking up to a power outage as the batteries magically slip below their shut down point. 

    Your warnings about deleterious effects on the food? Yes, that would be a huge negative. As a person who thinks many problems are solved via reasonable compromise, I see this possible solution. During the worst months shut down the power to the fridge/freezer for 2-3 hours right before the sun comes up and does its magic. 

    "BB - I do not think that turning power off at night really saves much, if any energy... The compressor simply runs longer the next day to bring temperatures back down to setpoint (in my humble opinion)."

    Same energy consumption - yes. But the energy comes from the panels instead of tired batteries yearning for the next days solar photons. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 31,161 admin
    True, advantage of you are trying to conserve battery power, off at night.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,561 ✭✭✭✭✭
    Not sustainable turning off a refrigerator offgrid at night. It means the design is wrong and it will bite you when you may have other issues. The snowball effect.

    If it does not matter spoiling the food then I guess it is a strategy. The medical warning is always "don't get sick"

    Your usage sounds high for that size. Have you ever cleaned the coils?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • softdownsoftdown Solar Expert Posts: 3,494 ✭✭✭✭
    Not sustainable turning off a refrigerator offgrid at night. It means the design is wrong and it will bite you when you may have other issues. The snowball effect.

    If it does not matter spoiling the food then I guess it is a strategy. The medical warning is always "don't get sick"

    Your usage sounds high for that size. Have you ever cleaned the coils?
      "During the worst months shut down the power to the fridge/freezer for 2-3 hours right before the sun comes up and does its magic."

    That is historic damage for 2-3 hours that would cause the temp to increase by 2-3 degrees. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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