Refrigerator power

2

Comments

  • steelsteel Registered Users Posts: 5
    Re: Refrigerator power

    I just made a chest refrigerator from a used 7.2cf chest freezer. I've had it on my kill-a-watt for 10 days now and it's avg 0.3 kw per day. These are not for everyone if you are used to a big conventional fridge but I did it for a test project. I'll eventually be building an off-grid cabin and wanted an alternative to those expensive propane or DC fridges.

    Has anybody else done this?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Refrigerator power

    as a matter of fact, yes, it has been done successfully before. do a search and you should find it or somebody may have it and can give you the link to the page.

    here's one i found,
    http://forum.solar-electric.com/showthread.php?t=9&page=6

    i don't remember if there were more.

    edit to add that bb and i both came up with the thread pretty much at the same time.
  • BB.BB. Super Moderators, Administrators Posts: 30,219 admin
    Re: Refrigerator power

    Steel,

    Yes--a number of people have... From Niel's April post:

    Chest Freezer as a Chest Refrigerator:
    http://forum.solar-electric.com/showthread.php?t=9

    Can work out very nicely. Low power, does not dry out food, opening the door does not dump cold air out. Add an accurate thermostatic control and you can set some pretty accurate near freezing temps for longer storage (if you want).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • steelsteel Registered Users Posts: 5
    Re: Refrigerator power

    Yeah, mine's been working great for about two weeks. I set the temps right above freezing and food is staying fresh way longer so far. Veggies that would start going bad in three days in a regular fridge are still fresh and crisp after 10 days. Thanks for those links. One problem mentioned was moisture on the walls. I've noticed that too. I'll keep a towel nearby to wipe it down every so often.
  • BB.BB. Super Moderators, Administrators Posts: 30,219 admin
    Re: Refrigerator power

    I believe one person just glued on a plastic "gutters" and directed them to a drain tube (should be a defrost drain in the base of the freezer). Took care of the condensation puddles in the bottom of the unit.

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

    One way to help reduce wintertime fridge use is to freeze jugs of water outside then place them in the fridge. I keep several on hand so I can rotate them in and out as needed. A fully-frozen gallon jug of water will stay icy for a week or more! This really cuts down on the fridge run-time. There is a lot of energy ( or lack thereof) stored in those frozen blocks!
  • mikeomikeo Solar Expert Posts: 386 ✭✭✭
    Re: Refrigerator power
    An 18 cu ft Energy Star refrigerator I looked at is rated to use 382 kWh per year.

    Here is the best rated that I have found listed so far: a 19 CF model
    http://www.ajmadison.com/cgi-bin/ajmadison/W9RXXMFWQ.html

    EntergyStar rating is 343kw/hours year.
    This model is also available at some of the big box stores at approximately $700
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Refrigerator power

    Go to the Energy Star web site and look at fridges for a start. You can download an excel spread sheet of about 1300 models from various manufacturers.

    You should be able to get down in the 250 kWh/year range.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,088 ✭✭✭✭✭
    Re: Refrigerator power

    I heard the energy star 2010 for refrigerators was do to be updated sometime this year.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • TelcoTelco Solar Expert Posts: 201 ✭✭✭✭✭
    Re: Refrigerator power

    Icarus - On your Nov 22 2008 comment I think I can shed some light on why fridges are as they are.

    Back in the good old days, refrigerators had one large door and the freezer was mounted in the top. All the cold air came from the freezer alone. Since the freezer was inside the fridge, the fridge area was kept cold by leakage from the freezer into the fridge area. Since cold air falls, it made sense to have thefreezer in the top. Warm air at the bottom would rise, where the freezer would chill it, making a natural convection inside the fridge. This also catered to the level of technology. It wasn't until later that technology progressed to where they could use two separate boxes with one compressor and be able to keep both boxes at the correct temperature. By then, we were all used to top mount freezers. We converted a little over a year ago from a Maytag non-estar top freezer to a Fridgidaire side by side estar unit, and I've been missing that top freezer.

    On the compressor location, a compressor is heavy so they want it at the bottom for safety. A top heavy fridge with a lot of stuff in the door might tip over when the top door is opened. So, compressor goes in the bottom to the back.

    Sunfrost has a concept that uses cold to transfer heat through the wall, listed here. I always thought this was a neat concept. However, ever since discovering the whole absorption cooling stuff, I'd have to wonder if there would be a way to build an absorption fridge and use solar heated water for it. If there were that would be amazing because I'd just be able to run everything off a combination of solar heated water and solar panels.

    No idea if an existing gas-fired absorption fridge would be able to be modified to run off a hot water source instead of a flame since a flame setup would be using a hotter heat source. I understand the concept but have never actually seen one in action or seen an actual diagram of the setup. Anyone know if this would be a feasable thing to do? I'm not in a position to do any experimenting, right now I'm hard at work trying to get my McMansion sold so I can get to a place more suited to two people now that both kids are pretty much out of the house. Had both gone for about 6 months but circumstances forced them to start fouling my nest again.

    I'd still love to do a chest fridge, but after long discussions with the 'ol lady she isn't having it. I've got to use conventional firepower on this. She likes the idea of going offgrid and using the sun for as much as possible, but she's not wanting to give anything up either. Making it tough...
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Refrigerator power

    İ was looking at the Sunfrost pages where they claim the RF16 model uses about 15 kWh per month.

    İn Energy Star the same is shown as 21 per month (252 per year). Sunfrost is also showing the Energy Star logo.
  • BB.BB. Super Moderators, Administrators Posts: 30,219 admin
    Re: Refrigerator power

    The Sunfrost has lower energy usage for non-energy star testing because they use a lower room temperature for their kWhrs per month vs Energy Star ratings (70F vs 90F).

    Also, The R16 is only 14.3 cuft... of internal space. They are not inefficient--just not that much better than an off-the-self energy star rated fridge from the local appliance store--especially once you scale for volume and features like frost free and other options.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Refrigerator power

    Sunfrost is at 20% better than the federal standard which is the least possible and still be Energy Star.
  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: Refrigerator power
    lotek wrote: »
    Dayton Ohio, My sister-inlaw lives there, and its FREEZING that time of yr.
    Just put the frig on the porch and you wont have a power bill for it.
    Back in the day. when I lived in the north Ga mountains, we did this, and had to put the milk inside the house at night to keep it from freezing. The house would get down to around 45 at night after the fire whent out, but warmed rapidly after the cook stove was stoked for morning coffee.

    You don,t want to put some of the newer refrigerators in the cold now. The computerboard shuts them down and you lose your food. The GE model I had previously says in the owners manual to keep the fridge in the house. I gave it to my daughter as an extra fridge as the side by side she had is limited in width. I always wanted a side by side till I saw the disadvantages of them. She put the GE in the garage before in her other house and lost all her frozen food. She moved again and put the ge in the garage and lost all the frozen food again. Thought she would have learned the lesson from the first time. When that fridge shuts down because you put it in the cold the computer board in it has to be reset. Vic
  • BB.BB. Super Moderators, Administrators Posts: 30,219 admin
    Re: Refrigerator power
    solarvic wrote: »
    You don,t want to put some of the newer refrigerators in the cold now. The computerboard shuts them down and you lose your food. The GE model I had previously says in the owners manual to keep the fridge in the house. I gave it to my daughter as an extra fridge as the side by side she had is limited in width. I always wanted a side by side till I saw the disadvantages of them. She put the GE in the garage before in her other house and lost all her frozen food. She moved again and put the ge in the garage and lost all the frozen food again. Thought she would have learned the lesson from the first time. When that fridge shuts down because you put it in the cold the computer board in it has to be reset. Vic

    Well--that is absolutely terrible. :confused:

    I can see issues where the freezer temperature is based on how much the refrigerator needs to run--and if in a 35F garage--the refrigerator never needs to run, so they will defrost the freezer.

    How many refrigerator/freezers have separately controlled and cooled fridge/freezer compartments... The "SubZero" lines have some versions with two compressors--one for freezer and one for refrigerator control (but not a cheap unit).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • momofgcmmomofgcm Solar Expert Posts: 35
    Re: Refrigerator power

    There is nothing in a fridge/freezer in the 18-19CF range that is rated in the 250's. I wish there were!!

    I looked at the ESR matrix and if you want an upright in the 18-19CF range you can get as low as ESR 335 but that's for a hotpoint.

    Hotpoint, GE, Frigidaire are lowest in energy consumption.

    I prefer the reliability of a whirlpool and you can get their ESR as 343 as mentioned in Mikeo's post. It's a very basic 19CF whirlpool.

    I am willing to give up 8W of 'calculated' wattage for what I think is the more reliable product.

    Kim
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,088 ✭✭✭✭✭
    Re: Refrigerator power

    Kim,

    Energy star is suppose to start a "top 10" program in May that may help you and all of us. What change from a program that rated how much power a tv used when turned off...they are getting useful!:roll:
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • momofgcmmomofgcm Solar Expert Posts: 35
    Re: Refrigerator power

    That would be WONDERFUL!

    Kim
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: Refrigerator power

    Not sure defrosting "the old fashion way" was a good way. Dumping most of box cool and rebuilding it back up is not very efficient. Also new refrig's do not have evaporator exposed like the old fashioned unit.

    Living in humid S. Fla. I don't have much of an option. I did try it and compressor run time extended within a couple of days without defrost.

    It did force me to make the measurements and it turned out defrosting did not consume that much in comparison to normal run consumption. The peak defroster power on my 25 cu ft. was 1000 watts but for the 20 minute defrost cycle the heater was toggled on and off, only totalling 5-6 minutes of actual heater on time. Defrost cycle sequenced every 18 hours.

    The enclosed evaporator concentrates the defroster heat leaving much of the refrig internal and cooled contents coasting through the cycle.
  • SpartanScottSpartanScott Solar Expert Posts: 41
    Re: Refrigerator power

    I have a 2003 KitchenAid ~25cu ft fridge. Without defrosting it consumes 1.18 kWh per day average. It has auto-defrost which has been running about once a week. I have logged and plotted the fridge power consumption during two defrost cycles (see attached). The first defrost required 251 Wh of extra energy to defrost and re-cool fridge/freezer back to normal temps. The second defrost (8 days later) used 247 Wh. Indoor temp at time of defrosts was 66F and 40% humidity.
  • BajaGringoBajaGringo Solar Expert Posts: 40 ✭✭
    Re: Refrigerator power

    Any particular reason you would not use a propane fridge in lieu of electric? Going to propane changed my power needs dramatically allowing me to run my big 50" plasma screen guilt free...
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Refrigerator power

    The economics of propane are complicated. If you are full time, conventional energy star is far and away the best way to go. If you only use weekends, and the occasional holiday week, then propane wins hands down. Somewhere in between the lines cross, and everyone must make their own choices.

    LP fridges can be had reasonably priced if you shop carefully, especially RV types in RV wrecking yard. They are also prone to failure if they are not run exactly level, ergo buying a used one comes at some risk. LP fridges can also be made more efficient if you add evaporator and condenser fans, and add rigid foam to the outside of the cabinets. They also are smaller than most conventional fridges. My only experience with large sized LP fridges has been bad! I believe it was "explorer" who took a conventional full sized fridge case, and installed a cooling unit off a large size LP fridge. The results were terrible. We couldn't keep them cold in the summer unless we covered them with a blanket, and kept fans on the condensers.

    Tony
  • BajaGringoBajaGringo Solar Expert Posts: 40 ✭✭
    Re: Refrigerator power

    We live a distance away from the grid, full time. We use a Norcold 12 cu ft fridge and it has worked great. A 20 gallon propane fill lasts us at least 3 months and as it is just the wife and I we have never found that we were lacking fridge space nor have we had any mechanical/operational problems.

    My personal opinion is that we have become so accustomed to the Costco mentality of stocking up on bulk quantities of foods that we keep looking to buy a bigger fridge. I know because there was a time I did the same thing. 12 cf seems to be just right. If company shows up for several days we can just fire up the unit in our motor home and that extra fridge space can get us through any Thanksgiving holiday.

    We did pick up our unit used but of course we did some shopping around and my advice to everybody is not to buy one unless you have seen it actually working as some folks don't take care of them as they should. When I did the calc for the cost of running a fridge on my solar panels and batteries it just seemed that propane made so much more sense. But like most in life, YMMV...
  • chevensteinchevenstein Solar Expert Posts: 100 ✭✭
    Re: Refrigerator power

    I'm going to have to go with BajaGringo on this one. We live off grid where sunlight is a precious commodity four months of the year and the extra $1000 to get a large LP fridge was well worth not having to double the size of the battery bank and add more panels. LP consumption is hardly noticeable above what the water heater, central heating, and stove use.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,088 ✭✭✭✭✭
    Re: Refrigerator power
    icarus wrote: »
    If you are full time, conventional energy star is far and away the best way to go.


    Tony

    There are people just starting a life offgrid. I have done many of their homes so that they do not have to worry about feeding an electric refrigerator. These lower priced systems with LP reefers allow people to live normal energy lives. In the end you are either buying fuel or buying batteries in these lower priced systems.

    So, I disagree with you Tony.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Refrigerator power

    Dave,

    I find myself both agreeing and disagreeing with you. I think it is really an individual choice, but one that is indeed hard to quantify. My only point is that the numbers begin to favour a conventional the more it is used.

    If you factor in purchase cost, KWH used/LP used, the price of that LP effect on battery life etc IMHO conventional makes sense for full time, understanding that there is more upfront PV system cost, but lower fridge purchase cost (typically)

    Comparing new to new, LP fridges are nearly twice as expensive as a good energy star model. The spread get greater as the LP fridge gets bigger. I figure that my fridge, that uses 1500 btu/hour, and has a duty cycle of ~25%on a annual basis will therefore use ~9000 btu/day,, or about 1/8 of a gallon in round numbers. My current cost for LP is ~$4 gallon, plus what it costs me to haul it. (No delivery here thank you very much!) This makes 45 gallons of fuel per year +-. at a cost of ~$180.

    An energy star fridge would use ~.75kwh/day. to generate that power I would need, by my calculation, ~ 400 watts of PV more, plus another 30 amps worth of controller, plus perhaps another pair of T-105s. So, 400*2=$800 for Pv, $300 for controller, $200 for batteries, for a total increase cost of say $1300, (with a 5 year battery cost of $40/per year).

    For that, I would get a bigger fridge, with a cost savings of ~$300 maybe. so at the end of ten years, a reasonable life expectancy the numbers might look like this.

    Battery cost, 10 years @ $40=($400)
    Fridge cost savings 300
    Fuel savings 1800
    Total savings over 10 years $1700

    One can run what ever numbers one thinks are real and come to ones own conclusion. I still suggest, that over time if you are going to live full time, a conventional wins at some point.

    Tony
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,088 ✭✭✭✭✭
    Re: Refrigerator power

    Tony,

    And I have seen you post your advice before and bit my tongue. My only point is I am not considering the cost, but rather the chance of success with a new client that is really clueless. I get a few... And yes they are all different. I just can't take the chance with someone having to run a generator unattended to feed a refrigerator on an 18K$ system. People have to leave their homes for days or weeks and it is a no brainer for me to put an 18 cu. ft Crytal Cold in, no matter what it costs on a spread sheet.

    Success is the goal! Peace of mind is the by-product! It is too beautiful in some of these places to be messing arround with generators. Hope you have a great spring!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Refrigerator power

    For what it's worth, I've done both propane and electric.

    Started with propane. As we spent more and more time at the cabin, the propane 'frige got to be a pain. It wanted a lot of gas and would go out unexpectedly in the middle of the night. It also had limited capacity.

    The capital expense of the 120 VAC for the electric refrigerator was enormous. There was additional justification in the need to supply power for the computer/satellite and water systems. These enable our spending more time there, so the capital is actually divided (as it were) among the three applications. Outlay for an electric 'frige is tiny compared to propane, especially on a size comparison basis.

    Less than $2,000 for a propane unit plus a tank now and then is nothing compared to the $8,000 PV system.
    But you can't run a computer off propane (generators notwithstanding). Propane is quieter than electric, but the electric never runs out causing a sudden lack of cooling.

    There's pluses and minuses to each. You have to look at all the factors and consider how the options will fit with your usage.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Refrigerator power

    Dave,

    It seems that we are picking nits here. But you say that you "don't consider the cost". While that may be appropriate for you (and your clients) it may not be for everyone. I don't think there is any reason for anyone to bite their tongue unless what I am saying is patently wrong, rather than just an opinion one doesn't share.

    I am only giving my opinion, and that is, Conventional fridges make more sense (financially) the more that they are used. Everyone has to come to their own conclusions. If your clients are such that they can't figure out that living off grid comes at some cost/sacrifice (lessons that many of us have learned through the school of hard knocks) and using L/P fridges is a solution that works for you and your clients that's great.

    We run a generator (to charge batteries) perhaps 5 days a year. We have a fairly well balanced system such that we have several days reserve without drawing the batteries down more than ~30% and one good sun day will bring them back to 100%.
    My point is, if I wished to add ~750 wh/day of capacity, I know quite well how much bigger my PV system would need to be to stay in that balance. Like I said in the previous post, in my case ~$1300
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,088 ✭✭✭✭✭
    Re: Refrigerator power
    icarus wrote: »
    Dave,



    We run a generator (to charge batteries) perhaps 5 days a year. We have a fairly well balanced system such that we have several days reserve without drawing the batteries down more than ~30% and one good sun day will bring them back to 100%.
    My point is, if I wished to add ~750 wh/day of capacity, I know quite well how much bigger my PV system would need to be to stay in that balance. Like I said in the previous post, in my case ~$1300

    Hey Tony,
    And my point is if you did this, you would be running the generator alot more. If you had to leave for a week, or you were busy building a home, you would one day come home to spoiled food and deeply discharged batteries. Your golf carts would be wrong for the job. In your location one would have to program an unattended generator if you were not home. Your solar for charging in December and January would go way up in your location. After doing fire insurance investigations on these strategies I keep small systems easy. One day the owner can go electric when they understand what is involved.

    One would also find out that in a small system that they can conserve and get by (like you do) in bad weather with propane. You will give that up with an electric and yes we are saying the same things. I am taking the chance of failure to a level that is acceptable to ME! I think Marc is correct in his 8K$, which is low down here to make your system relaible for electric.

    In the end, in these small systems, you will either be lifting batteries or paying for more fuel. In your location, I think you will be paying for fuel either way in the deep winter. Maybe this discussion will help someone! There are not too many of us!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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