Off grid, looking for a refrigerator that will bring my inverter out of standby

dougahole
dougahole Registered Users Posts: 13 ✭✭
in General Solar Power Topics #1
I am looking for some advice regarding the purchase of a new refrigerator. For background, I use an AIMS 3 kw pure sine wave inverter. It is a great inverter and I really like the standby (sleep) feature. When my refrigerator needs to start it brings the inverter out of sleep mode and for me that is a great advantage as I am able to conserve power, especially when I am not home and there are no other loads. Now, I would like to buy another refrigerator but the modern technology is causing some consternation. My daughter also off grid, purchased a refrigerator recently, and it will not bring the same inverter out of standby. Therefore she has to be 'on' all the time, no 'standby'. This uses more power. For those who live in the Great White (meaning snow) North, saving power is important, especially in Nov-Dec. So, I do not have enough faith in local retailers to tell me if I am buying the correct fridge for my needs.
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  • 706jim
    706jim Solar Expert Posts: 519 ✭✭✭✭
    #2
    I ran my inverter for many years using the standby feature. When I bought an electric fridge I realized very quickly that standby was no longer an option. Plus I started leaving my PVR running 24/7. My thoughts on inverter standby is that the amount of power saved is insignificant not to mention the defrost cycle timer which would be interrupted if the inverter shuts off. What sort of system do you have? I'm aware of the limited amount of solar at this time of year so you may have to consider generator backup from time to time. The good thing about that is that you can purchase whatever fridge you really want. The difference in power consumption between an apartment size fridge (mine in my signature) and a full size one is 300 compared to maybe 550 Kw-hr per year. 
    Island cottage solar system with appriximately 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing due south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter which has performed flawlessly since 1994. Outback Flexmax 80 MPPT charge controller four 467A-h AGM batteries. Insignia 11.5 cubic foot electric fridge 1/4hp GSW piston pump. My 31st year.
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,166 ✭✭✭✭
    #3
    I am not familiar with AIMS, but you need an inverter with an adjustable search watts trip point. The equipment that I am familiar with has the ability to come out of standby with setpoints between 5 watts to 50 watts. Hopefully, you can find the trip point that works for your refrigerator.
    I always have more questions than answers. That's the nature of life.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    You need a old fashioned manual defrost fridge  that goes completely off line when cold.  then it warms up and the thermostat clicks back on, and the inverter wakes up.

    Modern fridges with electronics and "self-defrosting" never really go to sleep and a inverter always sees some load
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,889 ✭✭✭✭✭✭
    #5
    I would add that if you are concerned with search or defrost cycles, you really are not in the modern world.
     Your power system design needs to be large enough to accommodate the power usage. 

    These are not issues for anyone I know ;)
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • New_Mexico_Will
    New_Mexico_Will Registered Users Posts: 107 ✭✭
    #6
    Being in the modern world is highly over-rated.   

    I don't know what model of AIMS inverter you have, but mine has an adjustable power save, so maybe yours does too.

    You can still buy manual defrost refrigerators, even at big box stores.  Just look for it as a filter in your search results.
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  • 706jim
    706jim Solar Expert Posts: 519 ✭✭✭✭
    #7
    It's been posted here in the past that skipping the defrost cycle can actually increase energy consumption in some cases plus possibly lead to spoiled food.
    Island cottage solar system with appriximately 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing due south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter which has performed flawlessly since 1994. Outback Flexmax 80 MPPT charge controller four 467A-h AGM batteries. Insignia 11.5 cubic foot electric fridge 1/4hp GSW piston pump. My 31st year.
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  • New_Mexico_Will
    New_Mexico_Will Registered Users Posts: 107 ✭✭
    #8
    Skipping the defrost cycle is not the same thing as having a manual defrost refrigerator,  which of course has no defrost cycle.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,889 ✭✭✭✭✭✭
    #9
    Living in the modern world may be over rated by you, but I will tell you that zero of the women I know offgrid want to manual defrost. There is alot to be said about living like your grandparents that is good. Being over concerned with energy was not a good memory.

     I am lucky to know quite a few from my experience with over 300 offgrid homes. I get that a cabin is not the same thing. It does not have to be hard though. Much better to get outside and love the place you live.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • dogdude
    dogdude Registered Users Posts: 15 ✭✭
    #10
    Dave, would you say that it’s best to use modern and typical appliances and build your system to accommodate them as opposed to using DC fridge, etc.? Just trying to get my bearings before I put my system together.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #11
    What is the size of solar power system you are looking at? >~3,300 WH per day--I would guess that a full size 120/230 VAC fridge would be a better fit (cheap fridge, standard service folks, relatively long life).

    If you are looking at a small system (less than 1,000 to 2,000 WH per day), possibly just a summer / weekend cabin--Then a DC fridge (with possibly a small ~300 Watt or so AC inverter for simple AC loads like laptop charger, TV, LED lighting, etc. when needed) could be more economical.

    Batteries are a huge cost (and risk of user damage through poor maintenance, over/under charging, etc.) and can be ruined in a week of visitor miss-use... Keeping the battery bank small has its advantages.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,889 ✭✭✭✭✭✭
    #12
    Batteries do not have to be a huge cost if the system is designed right and monitored when strangers are in town. It all can be done these days!

    I can see how you would say that Bill because you see that here alot on the forum. In real life with folks that have done their due diligence, Offgrid is a wonderful way of life!  No snow here today !  Merry Christmas !

    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • 706jim
    706jim Solar Expert Posts: 519 ✭✭✭✭
    #13
    dogdude said:
    Dave, would you say that it’s best to use modern and typical appliances and build your system to accommodate them as opposed to using DC fridge, etc.? Just trying to get my bearings before I put my system together.
    Trust me, go with modern appliances and a system large enough to run them. (Maybe forget the dishwasher....) DC stuff is expensive, harder to find and you will often have problems with voltage due to line losses at 12 volts. due to voltage lost and appliance cost.
    I wired my cabin with dual 12 volt and 120 volt circuits. Never use the 12 volt circuits due to voltage loss and appliance cost.
    Island cottage solar system with appriximately 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing due south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter which has performed flawlessly since 1994. Outback Flexmax 80 MPPT charge controller four 467A-h AGM batteries. Insignia 11.5 cubic foot electric fridge 1/4hp GSW piston pump. My 31st year.
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  • dogdude
    dogdude Registered Users Posts: 15 ✭✭
    #14
    Great! Thanks for input.
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    edited January 2021 #15
    AIMS inverters have fairly high no load power consumption.

    Standby mode wakes up periodically and sniffs the breeze for load current.  Problem with a micro-controller based appliance is they may have a low current boot up time that exceeds the short time the inverter stays on during standby wakeup sniff.  

    You might give AIMS a call to see if there is an easy way to extend the standby wakeup period to make it long enough for refrig to complete its boot up time.  At least you might get them to tell you the sleep period interval and length of active sniff period  It would be good if you measured the time it takes from point you plug in refrig until compressor turns on.  If it is a significant amount of time or longer then inverter sleep cycle period then you're screwed.  You can probably get an idea of inverter standby sleep cycle by plugging in an LED night light that doesn't have enough load to keep inverter on.  It will flash in sync with inverter sleep cycle.

    Looking at manual it appears to wakes for load detection for 250ms 'ON' period with sleep cycle of 3 seconds.  250 msec is too short to do uC boot, self checks, and turn on compressor to get enough load to keep inverter from returning to sleep mode.

    I would bet you are not the only one requesting a solution to this problem.  It would be nice if they allowed you to adjust the sleep period and length of wakeup time to keep the sleep time duty cycle high enough to get a reasonable standby power savings.
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  • dougahole
    dougahole Registered Users Posts: 13 ✭✭
    #16
    i know that it has been some time since made this post, but thanks just the same. with almost ALL refrigerators  'energy smart', there is little way to get around it. I had to  bite the bullet and take the system OFF 'STANDBY' and it takes a lot more power that I can not afford, especially during the dog days of early winter.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,889 ✭✭✭✭✭✭
    #17
    Nothing new here, it is time to redesign your power system to have the capacity to do what you want. Winter is what we design for. Just add money  ;)

    I remember a similar conversation back in the 1980's when Trace invented search mode. People were saying what good is it if you have a frost free refrigerator? Some people back then used a small incandescent they wired into the refrigerator to pull the inverter out of search. I think it worked for some but was unreliable also for many. Might search the forum here for that one.....

    You would think with modern refrigeration with 15 inch video displays on each door, wifi, and apps for the phone, that someone would build an app that could do what you want.

    The fridge might cost more than a bigger set of batteries and more panels. ;)

    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,101 ✭✭✭✭✭
    #18
    Dave Angelini said:


    You would think with modern refrigeration with 15 inch video displays on each door, wifi, and apps for the phone, that someone would build an app that could do what you want.



    Wouldn't it be nice it these new fridges could like....make a salad or sandwiches via wifi for you?  Everything ready for you when you get home from work.  :#

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,889 ✭✭✭✭✭✭
    #19
    Being so close to happy hour I think that Arthur the android bartender would be better than a smart fridge.

    https://www.youtube.com/watch?v=1v-OdpxRZp4

    Unfortunately there is also a video of when he malfunctions. I won't link that one. Spoils the buzz!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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