Inverter Problems/Head scratcher

LesVos98LesVos98 Registered Users Posts: 8

Hi All,

I have a little bit of a head scratcher. I have 600w of PV array going done through an 40amp MPPT to a battery bank of 558 A/H. From there it runs a 3000w Mod sine wave to run my fridge and soon hopefully my freezer as well.

This all works well except for this part (Here come the head scratcher part).

Over the last couple of months, the fridge has worked well, the small ice compartment making enough ice for the whiskey (all just the essentials) :) .. but we have had some serious hot and bright days lately and now the fridge will only run at night when the voltage drops to below 13.5v, it starts and almost immediately switches off again. I thought that maybe a voltage regulator in the form of an old PC UPS would help but no luck..

Any Ideas.. (I can't drink whiskey with out ice, that is just cruel and unusual punishment) :

Trying to go GREEN

Comments

  • Raj174Raj174 Solar Expert Posts: 493 ✭✭✭✭
    edited January 2016 #2
    Hello LesVos98,
          I think there may be a good chance that the problem is the modified sine wave inverter. They generally do not get along with motors, compressors, florescent lights, microwave ovens and some other devices. The modified sine wave causes inefficiencies that create heating and sometimes odd noises in these devices. This heat may be damaging the windings in the compressor of the refrigerator. The only way I have heard of to test this is to borrow or buy a pure sine wave inverter to verify the problem and replace the old one. A 2000 watt should be large enough for a refrigerator and a freezer. 1500 watt for just the fridge. Hopefully, other forum members will give you their thoughts on this problem also.
    Good luck
    12 x 300W Renogy PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 195AH HI Power LiFePO4 no BMS, 4000W gen.
  • LesVos98LesVos98 Registered Users Posts: 8
    Raj174 said:
    Hello LesVos98,
          I think there may be a good chance that the problem is the modified sine wave inverter. They generally do not get along with motors, compressors, florescent lights, microwave ovens and some other devices. The modified sine wave causes inefficiencies that create heating and sometimes odd noises in these devices. This heat may be damaging the windings in the compressor of the refrigerator. The only way I have heard of to test this is to borrow or buy a pure sine wave inverter to verify the problem and replace the old one. A 2000 watt should be large enough for a refrigerator and a freezer. 1500 watt for just the fridge. Hopefully, other forum members will give you their thoughts on this problem also.
    Good luck
    Thanks buddy.. My biggest concern is that it works well at night, ice and every thing, its just during the day.. I will / am trying to borrow a pure sinewave to test with so I will give that a bash as well..
    Trying to go GREEN
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Does the inverter work at all during the day, or is it just the fridge that doesn't work?  --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • LesVos98LesVos98 Registered Users Posts: 8

     vtmaps said:
    Does the inverter work at all during the day, or is it just the fridge that doesn't work?  --vtMaps

    The inverter works fine. TV phones ect.. just the fridge wont work during the day..
    Trying to go GREEN
  • LesVos98LesVos98 Registered Users Posts: 8
    oops not ect lol etc
    Trying to go GREEN
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    LesVos98 said:
     vtmaps said:
    Does the inverter work at all during the day, or is it just the fridge that doesn't work?  --vtMaps

    The inverter works fine. TV phones ect.. just the fridge wont work during the day..
    The only thing I can think of is that the inverter's waveform is different during the day when the input voltage is higher, and that your fridge can't tolerate the daytime waveform  ???? 

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BrockBrock Solar Expert Posts: 629 ✭✭✭
    I wonder if the inverter isn't regulated and stepping the voltage up say 10 times and pushing the top end of the fridge's limit?
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • Raj174Raj174 Solar Expert Posts: 493 ✭✭✭✭
    Lesvos98, 
        If you have a meter check the AC output of the inverter to see if the voltage is what it should be during daytime verses night. If the voltage is the same then vtmaps may be on to the problem. Of course you would need an oscilloscope to see the waveform. 
    12 x 300W Renogy PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 195AH HI Power LiFePO4 no BMS, 4000W gen.
  • mike95490mike95490 Solar Expert Posts: 7,357 ✭✭✭✭
    most meters are not going to give a good reading of a mod sine waveform.   I suspect the problem is your mod sine inverter and poor interaction with the motor in the fridge. 
    If you are going to go to a pure sine inverter, consider also upgrading to a 24V battery bank. instead of all the parallel batteries I know you have now.
    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
    gen: http://tinyurl.com/LMR-Lister ,

  • LesVos98LesVos98 Registered Users Posts: 8

     Mike95490,

    Thanks Mike, but I have a series of 2v cells lol. A forklift battery pack (actually a part of one- they run 48v). but I agree with the comments that the Mod sine is pushing out a different waveform when the battery is over 13.5v. And as RAJ174 pointed out I would need an oscilloscope.

    OH well.. Thanks to all for the comments and suggestions.. Seems like I will have to fork over for a pure sine wave.. :s


    Trying to go GREEN
  • BrockBrock Solar Expert Posts: 629 ✭✭✭
    They are more expensive but then things run more efficiently and everything will work without thinking about it.  I have a Xantrex prowatt 2000 for remote work and as a back up and it has been great, handled any single item you can plug in, including some larger tools.  I picked it up for under $400.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • EstragonEstragon Registered Users Posts: 1,683 ✭✭✭✭
    Just a thought, but could it be the temp of the fridge itself - starting the compressor being just a bit harder in the heat enough to overwhelm the inverter?.  I've found the output ratings on the cheaper mod sine wave inverters to be pretty optimistic.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • LesVos98LesVos98 Registered Users Posts: 8
    Estragon said:
    Just a thought, but could it be the temp of the fridge itself - starting the compressor being just a bit harder in the heat enough to overwhelm the inverter?.  I've found the output ratings on the cheaper mod sine wave inverters to be pretty optimistic.

    I had thought of that, but it turned out that it wasn't the case. If I plugged in one of the power tools and used it until the voltage dropped to under 13.5v the fridge ran like a dream.. seems as though I will have to go the PSW route.. or get a regulator that will only allow 13v and under thru to the MSW..


    Trying to go GREEN
  • SoloSolarSoloSolar Registered Users Posts: 2
    I'd say 600w is the bare minimum you're going to need to run an AC fridge. You might not have enough of a solar panel input to charge the batteries and run the appliance at the same time. I'd increase array size for sure (200w more at least) and maybe the battery bank, not 100% on that. Just a heads up that you wouldn't be able to run an AC fridge and freezer off that array, let alone one of them (as I suspect that is the problem).
  • LesVos98LesVos98 Registered Users Posts: 8
    SoloSolar said:
    I'd say 600w is the bare minimum you're going to need to run an AC fridge. You might not have enough of a solar panel input to charge the batteries and run the appliance at the same time. I'd increase array size for sure (200w more at least) and maybe the battery bank, not 100% on that. Just a heads up that you wouldn't be able to run an AC fridge and freezer off that array, let alone one of them (as I suspect that is the problem).T\

    Thanks for the input. Just to clarify, the fridge and freezer sips power and are HUGELY efficient, 300w and 600w per day respectively. The charge is no problem.. I live in sunny South Africa and we get huge usable daylight. Winter I am getting > 6.5 hours and summer is well over 10 hours on average. Normally by 10:00 am the battery is fully charged. I borrowed a small PSW, and the fridge is running well now, and the batteries are still over 13.5, and sometimes over 14v, at any given time, even when running my old camping fridge at the same time. (Its one of those gas/12v/220v thermo types).

    I have enough spare capacity to add to the system if I need to. This is a learning curve for me as well, one that I must say, has proved to be interesting.

    Trying to go GREEN
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Interested in what kind of fridge is it? 300Wh/d in high ambeint south africa is impressive.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • South AfricaSouth Africa Solar Expert Posts: 294 ✭✭✭
    So am I LesVos98.
    Make and models please.  :)

    While ago I went for a Hisense to try it out. Small fridge, wife is moaning but marketing material says it uses 150kwh per year!
    It is running beautifully on a pure sine wave inverter, 24/7/365 on solar only. Batts do not even feel it at night.

    But I need a bigger fridge, or another wife.  :p
    Suspect a bigger fridge will be the cheaper option.
  • SoloSolarSoloSolar Registered Users Posts: 2
    LesVos98 said:
    SoloSolar said:
    I'd say 600w is the bare minimum you're going to need to run an AC fridge. You might not have enough of a solar panel input to charge the batteries and run the appliance at the same time. I'd increase array size for sure (200w more at least) and maybe the battery bank, not 100% on that. Just a heads up that you wouldn't be able to run an AC fridge and freezer off that array, let alone one of them (as I suspect that is the problem).T\

    Thanks for the input. Just to clarify, the fridge and freezer sips power and are HUGELY efficient, 300w and 600w per day respectively. The charge is no problem.. I live in sunny South Africa and we get huge usable daylight. Winter I am getting > 6.5 hours and summer is well over 10 hours on average. Normally by 10:00 am the battery is fully charged. I borrowed a small PSW, and the fridge is running well now, and the batteries are still over 13.5, and sometimes over 14v, at any given time, even when running my old camping fridge at the same time. (Its one of those gas/12v/220v thermo types).

    I have enough spare capacity to add to the system if I need to. This is a learning curve for me as well, one that I must say, has proved to be interesting.

    I'm also in on the group that wants to know the make/model of it. I've got the 6.1cf here: http://www.c4pinc.com/solar/solar-refrigerator/ which runs at ~380wh/d and I don't have as high of an ambient temperature as you would.

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