12V/24V fridge&freezer

If my 12V/24V freezer Power consumption is around 1.5-2A @24v. so how big solar panels should i need if i need a solar system to provide the power to my freezer , and how big batteries ?
i use two pcs 50W solar panel and two 100 ahs solar batteries and 20A solar charge controller .it works very good ,but i think it;s two big . and ideas ?

Comments

  • SlappySlappy Posts: 251Solar Expert ✭✭✭✭✭✭
    Re: 12V/24V fridge&freezer

    http://www.sundanzer.com/Prod_Info_files/residential_system_sizing.pdf


    Tonyhan, the link above is from the sundanzer web site, hope this helps ;)

    but errr caution on the safe side.
  • System2System2 Posts: 6,290 admin
    Re: 12V/24V fridge&freezer
    Slappy wrote: »
    http://www.sundanzer.com/Prod_Info_files/residential_system_sizing.pdf


    Tonyhan, the link above is from the sundanzer web site, hope this helps ;)

    but errr caution on the safe side.

    sundanzer's price is so high ,i am manufacturer of all kinds of solar freezers in china.very cheap price
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: 12V/24V fridge&freezer
    tonyhan wrote: »
    If my 12V/24V freezer Power consumption is around 1.5-2A @24v. so how big solar panels should i need if i need a solar system to provide the power to my freezer , and how big batteries ?
    i use two pcs 50W solar panel and two 100 ahs solar batteries and 20A solar charge controller .it works very good ,but i think it;s two big . and ideas ?

    tonyhan,
    i am confused by your saying 12/24v freezer. are you saying that your freezer will work with either 12v or 24v for the same freezer?

    as to figuring out the batteries and pvs required that is based on what the load is over a day. does your freezer draw this 1.5-2a at 24v constantly (assuming this not workable for 12v) as i'll be it does not? now assuming 2a at 24v is 48w and for every hour running this is 48wh consumed which is nearly as much as 1/2 the solar input. the freezer has to run 24hrs a day, but the solar is not 24hrs a day with most getting 5hrs or less of full rated sun to base the pv power on. there's also efficiencies and losses to consider. if for example the freezer would run half of the time them this is 1ah (2a/2) and over 24hrs is 24ah. this would be able to run about 2 days with a 24v 100ah battery bank. you don't want to deplete the battery bank below 50% and is why it'll go 2 days and not 4 days.

    the power drained plus any inefficiencies and losses must be replaced back into the batteries by the pvs. solar only has so many hours in order to replace the power lost and if the worst case winter sun is say 3hrs then you have 3 hours to replace that which you lost keeping in mind the sun does not shine everyday. anyhow if we go by the 3 hours this means 24ah/3=8ah delivered to the batteries. because stc ratings aren't good real world ratings and there are other losses plus inefficiencies that some here would add 50% more to the pv's current output. this would mean 1.5 x 8a = 12a and this would be at 24v nominal for battery charging. the actual vmp voltage on a 24v nominal pv will be in the area of about 34v to about 39v or so.

    reworking what i see, the 12a in pv would charge a 100ah 24v battery bank at a 12% rate of charge and is acceptable as the normal range for fla batteries is between 5% and 13%. if, however, you would want to increase the battery capacity to 4 days worth (double) one must look at the charge percent to be sure the batteries will charge alright and it just so happens that you would have a 6% rate of charge so this would mean you could have a battery system ah of between about 100ah to 200ah no problem with a 12a pv output.

    with your 100w pvs this i will approximate as i do not know the actual amps output. 100w/35v vmp(guess)=2.86a which would be far short in my example. my example may be in the area of what your circumstance might be, but exacting i don't know.
  • System2System2 Posts: 6,290 admin
    Re: 12V/24V fridge&freezer
    niel wrote: »
    tonyhan,
    i am confused by your saying 12/24v freezer. are you saying that your freezer will work with either 12v or 24v for the same freezer?

    as to figuring out the batteries and pvs required that is based on what the load is over a day. does your freezer draw this 1.5-2a at 24v constantly (assuming this not workable for 12v) as i'll be it does not? now assuming 2a at 24v is 48w and for every hour running this is 48wh consumed which is nearly as much as 1/2 the solar input. the freezer has to run 24hrs a day, but the solar is not 24hrs a day with most getting 5hrs or less of full rated sun to base the pv power on. there's also efficiencies and losses to consider. if for example the freezer would run half of the time them this is 1ah (2a/2) and over 24hrs is 24ah. this would be able to run about 2 days with a 24v 100ah battery bank. you don't want to deplete the battery bank below 50% and is why it'll go 2 days and not 4 days.

    the power drained plus any inefficiencies and losses must be replaced back into the batteries by the pvs. solar only has so many hours in order to replace the power lost and if the worst case winter sun is say 3hrs then you have 3 hours to replace that which you lost keeping in mind the sun does not shine everyday. anyhow if we go by the 3 hours this means 24ah/3=8ah delivered to the batteries. because stc ratings aren't good real world ratings and there are other losses plus inefficiencies that some here would add 50% more to the pv's current output. this would mean 1.5 x 8a = 12a and this would be at 24v nominal for battery charging. the actual vmp voltage on a 24v nominal pv will be in the area of about 34v to about 39v or so.

    reworking what i see, the 12a in pv would charge a 100ah 24v battery bank at a 12% rate of charge and is acceptable as the normal range for fla batteries is between 5% and 13%. if, however, you would want to increase the battery capacity to 4 days worth (double) one must look at the charge percent to be sure the batteries will charge alright and it just so happens that you would have a 6% rate of charge so this would mean you could have a battery system ah of between about 100ah to 200ah no problem with a 12a pv output.

    with your 100w pvs this i will approximate as i do not know the actual amps output. 100w/35v vmp(guess)=2.86a which would be far short in my example. my example may be in the area of what your circumstance might be, but exacting i don't know.

    Hi Nile:
    The freezer can work both in 12V and 24V . they are the same feezer ,but i think we use 24V is more table than 12V, in fact the freezer didn't work all day long,
    the compressor will stop when it reach at the temp. which adjusted . by the way the freezer can adjust the temp. from 10 C to - 18 C ,when is the compressor stop depend on how much things did you put into freezers and how about the abinemt temp. if we use two 100 ahs batteries can last two days without pvs input the power, we tested this many times. the only question is the right solar panels and batteries can hold my freezers ,24 hours a day 7 days per week.
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: 12V/24V fridge&freezer
    tonyhan wrote: »
    Hi Nile:
    The freezer can work both in 12V and 24V . they are the same feezer ,but i think we use 24V is more table than 12V, in fact the freezer didn't work all day long,
    the compressor will stop when it reach at the temp. which adjusted . by the way the freezer can adjust the temp. from 10 C to - 18 C ,when is the compressor stop depend on how much things did you put into freezers and how about the abinemt temp. if we use two 100 ahs batteries can last two days without pvs input the power, we tested this many times. the only question is the right solar panels and batteries can hold my freezers ,24 hours a day 7 days per week.

    interesting that you have a freezer that is capable of both voltages. if you say it's unstable at 12v though then i guess we can assume it really isn't a 12/24v freezer.

    yes, the 2 100ah batteries you have in series is good to 2 days of use, but you must recharge the batteries or they will die and the freezer will not run anymore. what you have in pvs is inadequate to recharge the batteries. i tried to give a good estimate of what you may need for pvs in my previous post with my example, but i can't say for sure that it won't be more or less. if you have a utility charger then i suggest putting a charge to the batteries until you can get the proper amount of pv power for it to work properly.
  • System2System2 Posts: 6,290 admin
    Re: 12V/24V fridge&freezer
    niel wrote: »
    interesting that you have a freezer that is capable of both voltages. if you say it's unstable at 12v though then i guess we can assume it really isn't a 12/24v freezer.

    yes, the 2 100ah batteries you have in series is good to 2 days of use, but you must recharge the batteries or they will die and the freezer will not run anymore. what you have in pvs is inadequate to recharge the batteries. i tried to give a good estimate of what you may need for pvs in my previous post with my example, but i can't say for sure that it won't be more or less. if you have a utility charger then i suggest putting a charge to the batteries until you can get the proper amount of pv power for it to work properly.

    Hi Nile
    Our freezer can work both 12V and 24v ,But you see when we connect the freezer into the solar system .it's electrinic power is big when the compressor is starting working. maybe will last around one to five minutes. so that's why i'd like to use 24V out put. in my testing .we use two pcs 50W solar panel and two 100 ahs batteries ,it can work 24 hours a day 7 days per week .and even has two days no sun during that time .by the way ,my freezer has low vattage protection
    so don't worry about will burn the battery . any way the charge controller has this funtion too. and also the freezer&fridge is 258L ,if use our 138L chest freezer or 162 upright fridge&freezer .the power is more less than this .
  • FreeWattsFreeWatts Posts: 14Registered Users
    Re: 12V/24V fridge&freezer

    after two days no sun how long does it take to recharge the two batteries with only solar?
  • BB.BB. Posts: 25,254Super Moderators admin
    Re: 12V/24V fridge&freezer

    By the way, I believe this is the US Importer's Website:

    www.sundanzer.com

    Has quite a bit of information--including down to the compressor/electronics data sheets.

    Sorry about my earlier questions--I thought that this was designed for solar array only and batteries are not needed... Not the case, this needs a battery bank for proper operation.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Posts: 6,523Solar Expert ✭✭✭✭
    Re: 12V/24V fridge&freezer
    BB. wrote: »
    By the way, I believe this is the US Importer's Website:

    www.sundanzer.com

    Has quite a bit of information--including down to the compressor/electronics data sheets.

    Sorry about my earlier questions--I thought that this was designed for solar array only and batteries are not needed... Not the case, this needs a battery bank for proper operation.

    -Bill

    I thought those had been around quite a while, and the specs read better than they worked.
    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 ,

  • WindsunWindsun Posts: 1,164Solar Expert admin
    Re: 12V/24V fridge&freezer

    An older article here about DC reefers - http://www.backwoodshome.com/articles2/yago102.html

    We do not recommend the Sunfrost mentioned in that article, mainly because of the cost, which we think is way too high for what you get.
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: 12V/24V fridge&freezer
    FreeWatts wrote: »
    after two days no sun how long does it take to recharge the two batteries with only solar?

    this is a good question even though one could've surmised from the info i gave that it would take at least 2 days to recharge it as the pvs are basically just keeping pace with the freezer needs along with the losses and efficiencies also taken into account. add to that you still have a freezer that needs to run is essentially doubling your load at that point. this is where a generator or extra pvs over the stated 12a system example can come in handy. if one continued to drain the batteries by using the freezer on day 3, even with full sun for the prescribed number of hours, the batteries will remain roughly at equilibrium overall or about 50% dod as the power delivered to the batteries is being used up by the freezer. all power drained from the batteries will need to be replaced and is dependent in the case of solar by the amount of pv watts and the amount of insolation one receives.
  • pdxr13pdxr13 Posts: 6Registered Users
    Re: 12V/24V fridge&freezer
    niel wrote: »
    all power drained from the batteries will need to be replaced and is dependent in the case of solar by the amount of pv watts and the amount of insolation one receives.

    This is the problem faced by PacificNW solar-only people who either massively over-size PV/battery banks to deal with WEEKS of 0%-10% (of July peak) power production during cloudy (deadly wet-cold) December-January, or run genset with a 10-month solar system. One pre-TEOTWAWKI solution is to slightly oversize the battery bank and run a genset as-needed to charge during the darkness. Then there is the discussion of how inefficient it is to run a 6500W genset to operate an undersized electronic charger. Uhh-huh, run some tools and a few loads of laundry or heat water at the same time, or spend big on a charger that can put serious amps in the bank.

    A lot of people haven't yet figgered out that serious short-term useful power is best made with internal combustion engines. It's not a moral failure to use an engine-driven charger when it's the obvious-practical-cost-effective thing to do during times of darkness/cold/low-battery. It's a moral failure to be cold in the dark, without refrigeration, and the manual bilge pump isn't working.

    Cheers.
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