Suddenly living off grid 24/7 and need better refrigeration.....

K4KMGK4KMG Solar Expert Posts: 50 ✭✭
The system in my sig has been excellent for 2 yrs on a weekend basis. Never used the Dometic rv fridge as I just brought a cooler with ice for the weekends. I now find myself living at my camp permanently. The Dometic is running on propane and cools somewhat, but anyone that's ever used one of these knows they are not all that great.

I have a typical energy efficient refrigerator, (top freezer/bottom fridge), that I'd like to use here but I'm sure the current system would not handle the addition.

Question is: If I double my current solar, 4 of the same panels, 4 of the same batt's, and a 60a charge controller, would this be sufficient to add the fridge to the mix?
Kill o Watt gives me 95w and about 1 amp for the fridge.
Thanks
Camp can be seen at k4kmg.com

Comments

  • animattanimatt Solar Expert Posts: 295 ✭✭✭
    IF current system is working as it should. The new panels should take care of refrigeration just fine.
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    K4KMG wrote: »
    I have a typical energy efficient refrigerator, (top freezer/bottom fridge), that I'd like to use here but I'm sure the current system would not handle the addition.

    I'm wondering why. Has it been attempted yet, or still just planning?

    I live in Central Florida, with 225W panels, and get probably 1kwh/day average. On many occasions it is less, but it seems to me rare that it is less than 500wh/day/panel. So with four panels you can expect between 2 and 4kwh/day. For the (full sized) refrigerator, I'm seeing about 1.5kw/day usage. So yes, it could be cutting close on some days. I would think that a mini-fridge would use correspondingly less electricity though I don't have specific data for one at the moment.

    Now the batteries, 4 x 225ah = 900ah total. So to be safe 0.5kwh maximum, or 1/3 of the refrigerator usage if PV is not generating enough.

    Is it possible to try an experiment and run two 60w bulbs all day and see? Yes, it isn't the same as 150w on for 10 minutes, then off for 10 minutes, but it should be close enough for a test. But also I would think it will be much easier to recharge the four current batteries if necessary rather than essentially doubling the investment in PV to cover one (full sized) refrigerator. And if you can get by with a mini-fridge it should be even better. In an emergency too it would seem to be possible to buy ice, or maybe have planned ahead and made ice during sunny days, and keep things cold for a time and reduce the electric usage that way too, but obviously is expensive if you're buying ice.

  • K4KMGK4KMG Solar Expert Posts: 50 ✭✭

    I'm wondering why. Has it been attempted yet, or still just planning?

    I live in Central Florida, with 225W panels, and get probably 1kwh/day average. On many occasions it is less, but it seems to me rare that it is less than 500wh/day/panel. So with four panels you can expect between 2 and 4kwh/day. For the (full sized) refrigerator, I'm seeing about 1.5kw/day usage. So yes, it could be cutting close on some days. I would think that a mini-fridge would use correspondingly less electricity though I don't have specific data for one at the moment.

    Hasn't been attempted yet. I've only been here 2 days. Need to see how the current system stacks up full time. Already though, I get the feeling that current sys is just a little under what I'm going to need. Don't want to worry so much about every watt.

    Refrigerator is still in Vero and has a full freezer. If I bring it out here and power is insufficient, I'd lose about 600.00. (value of items currently in freezer portion)

    It's surprising how much electricity the rv fridge needs even though it's running on propane. With typical evening usage here, when I wake up I'm down about 30% on the Trimetric. Before the fridge, I only used about 20% in the evenings/overnight.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    If you want the most efficient means of refrigeration, consider a small chest freezer and convert it to operate at normal refrigerator temperatures. The insulation is FAR better, the cold air won't "pour" out when you open the door and it's consumption is likely to be around or less than 0.3 kwh per 24 hour day, depending on the size and efficiency of the "freezer". The drawback? Expect high humidity within the unit when operating as a fridge, but that's a HUGE plus when keeping vegies.
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    This is a great idea if one can convert the thermostatic control to allow ~40 F. How does one do that? Assuming the ability is not built in...
    If you want the most efficient means of refrigeration, consider a small chest freezer and convert it to operate at normal refrigerator temperatures. The insulation is FAR better, the cold air won't "pour" out when you open the door and it's consumption is likely to be around or less than 0.3 kwh per 24 hour day, depending on the size and efficiency of the "freezer". The drawback? Expect high humidity within the unit when operating as a fridge, but that's a HUGE plus when keeping vegies.

    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: 32,994 admin
    There are lots of mechanical and electronic thermostats. Get one with a remote temperature probe than can turn on/off AC line voltage to the compressor.

    Here are a couple of examples (have not used any of them--Just starting point to search):

    http://www.amazon.com/Johnson-Controls-Digital-Thermostat-Control/dp/B00368D6JA (electronic)
    http://www.northernbrewer.com/shop/johnson-refrigerator-thermostat (mechanical)

    If you have an inverter that "sleeps" when there is no AC load--A mechanical thermostat may be the better choice--Or make sure you get an electronic thermostat that runs on batteries when the AC power is turned off.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    Great dig....good price on the digital (top unit). The mechanical unit is cheaper and has a 3 1/2 degree in/out differential. That is a bit high but liveable. 38 degree milk is cold. 41 1/2 degree milk is warmer than I like. Also...Amazon offers that unit with free shipping.

    The default setting differential on the top unit is 5 degrees but is adjustable by the user.
    BB. wrote: »
    There are lots of mechanical and electronic thermostats. Get one with a remote temperature probe than can turn on/off AC line voltage to the compressor.

    Here are a couple of examples (have not used any of them--Just starting point to search):

    http://www.amazon.com/Johnson-Contro.../dp/B00368D6JA (electronic)
    http://www.northernbrewer.com/shop/j...tor-thermostat (mechanical)

    If you have an inverter that "sleeps" when there is no AC load--A mechanical thermostat may be the better choice--Or make sure you get an electronic thermostat that runs on batteries when the AC power is turned off.

    -Bill
    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
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    K4KMG wrote: »
    Don't want to worry so much about every watt.

    Refrigerator is still in Vero and has a full freezer. If I bring it out here and power is insufficient, I'd lose about 600.00. (value of items currently in freezer portion)

    As somebody who went through the three hurricanes here in Polk County, what I was able to do when the power was off was run the refrigerator on an APC Smart-UPS 750xl backup power supply. As the power was off for days, what I'd do is run the refrigerator, discharging the UPS, then go to my in-laws who still had electricity and recharge the UPS and bring it back home for the next round.

    Our refrigerator was Energy Star, and it worked fine with the UPS, but when I tried to use it with my mom's non-Energy Star refrigerator, it would trip the UPS and shut it down due to the startup current. So the advice is always have an Energy Star refrigerator!!

    Also, I thought if you were off-grid you always worried about every watt. I do even when on-grid.


  • BB.BB. Super Moderators, Administrators Posts: 32,994 admin
    I do like the electronic controls because you can get below ~3-4F degree spread on the high/low temperatures.

    Regarding any disaster prep.... Always test your setup/hardware/appliances before the power failure comes. Don't want any more surprises during a crisis.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Be aware that if using a mechanical thermostat for freezer conversion, the bimetal strip that controls the switch must be located inside the "fridge" and exposed to the high moisture level = rust and early failure. Been there, done that years ago.
  • BB.BB. Super Moderators, Administrators Posts: 32,994 admin
    That is why the remote bulb type are nice.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • K4KMGK4KMG Solar Expert Posts: 50 ✭✭

    As somebody who went through the three hurricanes here in Polk County,

    I'm at River Ranch POA in Polk cnty
  • Desert RatDesert Rat Solar Expert Posts: 131 ✭✭✭
    My GF runs an 18 cu. ft. fridge/'freezer, AND an 8 cu. ft. chest freezer with a 1320 watt array and 8 T-105 batteries. That's in addition to the usual lightsfansstereoTVcomputermodem. I've tested several conventional refrigerator/freezers, and found that we can expect the summertime draw here (often 105 deg. F.; and higher) to be 1.5 times the Energy Guide Label. Example: Energy Guide Label 380KWH/year/365=1041 wh/day. Actual usage=1500wh/day. This is here in sunny west Texas, YMMV.
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    It might seem that one could coat the strip with a very light coat of clear (preferably) silicone. Professional aquarist for 23 years. Silicone is magic.
    Be aware that if using a mechanical thermostat for freezer conversion, the bimetal strip that controls the switch must be located inside the "fridge" and exposed to the high moisture level = rust and early failure. Been there, done that years ago.

    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
  • oil pan 4oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    You can save your self about $30 and just buy the Johnson Controls A19ABA-40 thermostat adjustable from -30'F to 100'F, use your deep freeze as a fridge or a freezer at the turn of a dial.
    All you have to do is wire in your own cords if you have an extension cord you can butcher.
    If you want the most efficient means of refrigeration, consider a small chest freezer and convert it to operate at normal refrigerator temperatures. The insulation is FAR better, the cold air won't "pour" out when you open the door and it's consumption is likely to be around or less than 0.3 kwh per 24 hour day, depending on the size and efficiency of the "freezer". The drawback? Expect high humidity within the unit when operating as a fridge, but that's a HUGE plus when keeping vegies.

    What he said, the guys who have done the chest freezer to fridge conversion are posting stupid low consumption numbers, usually between 0.2kwh and 0.35kwh.
    By comparison my 2013 made Kenmore uses right around 1kwh per day.
    Energy star my arse.

    I have a stand up deep freeze that is out of service, it works, but I only store tools and a few bottles of booze in there which do not require refrigeration.
    I built an freezer to fridge thermostat with remote probe for just in case... I just keep it in the freezer along with the tools and jack.
    One of these days I need to pull all my tools out and plug it in, set the thermostat and see how much power it uses. When it was an actual freezer it used up to 2kwh per day, but reducing the temperature differential by about 50'F should cause it to use a little less power. I IR gunned the stand up freezer one day and it showed -20, by comparison my regular refrigerator's freezer only does about -10.

    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.

  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    My Energy Star upright 8 cu ft uses roughly 1 kwh/24 hour day as a freezer when the door was not being opened. It draws close to 100 watts when running.
    Converted for Fridge use and holding the temperature as close to the freezing point as possible without freezing things (I like ice cold water) , once it has cooled down, the compressor runs 5 minutes out of every hour. I've timed it many times.
    5 minutes times 24 (the hours in a day) = 120 minutes, or 2 hours out of 24.
    2 hours times 100 watts = 0.2 kwh. with the door kept shut.
    With the door opened a number of times a day, it increases in my case, to about 0.3 kwh/24 hour day.
    I got basically the same with my first conversion almost 15 years ago with a non Energy Star 5 cu ft chest.
  • vtmapsvtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    BB. wrote: »
    I do like the electronic controls because you can get below ~3-4F degree spread on the high/low temperatures.

    Also, the electronic controls have another great feature... the freezer will not turn on within 5 minutes of shutting off. That helps limit the startup surge that occurs when the compressor starts up against pressure from the previous cycle.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    In some cases, with mechanical (either bimetal or diaphragm type) thermostats you can extend the range by removing the knob and/or the rotation limiting plate from the adjusting screw and turning it one or more turns in the cold of hot direction and then reattaching the travel limiter. As long as it does not force the internal parts into an interference situation, it will often let you change a refrigerator range stat to a freezer range stat or vice versa.
    SMA SB 3000, old BP panels.
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    Was wondering about being able to do this with a household thermostat. These thermostats seem to "bottom out" around the 50 F setting. They can be purchased at a cheaper price. Whether or not they are adjustable in the manner you described? One will not know without tearing into it. Bit of a risk there. Unless has no qualms about returning merchandise that one has experimented with. Some will...I would prefer not to.

    Or...you are talking about customizing the existing thermostat in a freezer...
    inetdog wrote: »
    In some cases, with mechanical (either bimetal or diaphragm type) thermostats you can extend the range by removing the knob and/or the rotation limiting plate from the adjusting screw and turning it one or more turns in the cold of hot direction and then reattaching the travel limiter. As long as it does not force the internal parts into an interference situation, it will often let you change a refrigerator range stat to a freezer range stat or vice versa.
    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
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    Net pricing on that A19ABA-40 is all over the place. $115 with shipping at Amazon! $45 and up on Ebay. Temperature differential is a minimum of 3 F....a bit high in my opinion. My refrigerator never wavers from 40 F....on and off pretty often. Must have a differential of 1 F.

    Power wise....a 3 degree differential would consume less power...I believe.
    oil pan 4 wrote: »
    You can save your self about $30 and just buy the Johnson Controls A19ABA-40 thermostat adjustable from -30'F to 100'F, use your deep freeze as a fridge or a freezer at the turn of a dial.
    All you have to do is wire in your own cords if you have an extension cord you can butcher.



    What he said, the guys who have done the chest freezer to fridge conversion are posting stupid low consumption numbers, usually between 0.2kwh and 0.35kwh.
    By comparison my 2013 made Kenmore uses right around 1kwh per day.
    Energy star my arse.

    I have a stand up deep freeze that is out of service, it works, but I only store tools and a few bottles of booze in there which do not require refrigeration.
    I built an freezer to fridge thermostat with remote probe for just in case... I just keep it in the freezer along with the tools and jack.
    One of these days I need to pull all my tools out and plug it in, set the thermostat and see how much power it uses. When it was an actual freezer it used up to 2kwh per day, but reducing the temperature differential by about 50'F should cause it to use a little less power. I IR gunned the stand up freezer one day and it showed -20, by comparison my regular refrigerator's freezer only does about -10.
    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
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    I actually had to add a metal mass to the sensor and insulate it to slow down it's temperature change so the compressor wouldn't be starting every 5 minutes and running for only a few seconds. Adding more and more mass eventually permitted the compressor to run a full 5 minutes before shutting down again. It then didn't power on again for an hour, then ran again for 5 minutes. Works great this way and we only have one start surge per hour instead of one every 5 minutes.
    Just something to be aware of in case you run into the same problem.
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