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  1. #1
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    Default Help On Running a 220v Fridge on an Inverter/Solar Setup

    Morning All

    Apologies in advance for posting a heavily debated topic already, however, I have read a number of threads on the community regarding the pro's and con's of running a fridge via an inverter (all valid) but none quite answered my question/situation.

    A little background, I have a 2008 Gypsey Rhapsody, for those who may not know this is an on-road caravan with a 220v electrical system - lights & fridge with an internal gas stove. A family member has invited us down to his plot in Langebaan during December (last week foundations were laid for their new house), unfortunately, Eskom takes a while to lay mains power and there is no expectation that there would be any power available. The theory is that the basics of their house will be up and a space will be cleared for us to camp.

    What I would like to do is:
    1. Harness the power of the sun to run the fridge during the day only
    2. If required provide charge to a 48ah battery - the battery is in place already as it forms part of the Ewiks mover system (see point 3 below)
    3. Charge portable lights during the day - 1 x Magneto, 2 x Eurolux FS 207's
    4. Charge 2 x cellphones

    As mentioned there are a couple of excellent threads on the topic from which I have learned a tremendous amount, so far I have learned:
    1. The fridge has a "constant running" value (measured at 150w) and "startup load" (measured at 390w), I obtained these values by using my Kill-A-Watt device.
    2. From one of the threads a general rule of thumb is to use 3 x running watts to calculate safe startup wattage and ensure that the inverter has enough peak capacity.

    My questions are:
    1. Can a fridge run on modified sine? Fridge/Freezer is a Defy C220
    2. Would a single 410w panel deliver enough watts? What is the rule of thumb? By way of example https://www.solarwaysuppliers.co.za/...ar-410w-panel/
    3. Is a battery required to cover for the startup load and if so how would this be sized appropriately?

    In terms of inverter and with my limited knowledge this one seems to fit the bill:
    https://pclinkshop.co.za/ups-inverte...400mppt-clone/

    Any thoughts and advice would be greatly appreciated!

    Thank you in advance!

    Cheers

    David

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    I will leave the fine detail to the real boffins, but:

    1. I would not risk a fridge compressor on modified sinewave, as it uses an induction motor;
    2. 48Ah is a small battery and likely also not meant to be deep cycled.

    For a start I would therefore recommend going the route of a pure sinewave inverter and a larger battery. You could likely even rent from someone like Bushpower. If you are happy not to run the fridge at night, then the existing battery should be fine to ensure the inverter can cope with the compressor startup demand.

    410W of solar panel would IMHO be more than enough.
    ZS6VL


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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Hi An3s

    Thank you so much for the quick response, never even considered renting - I will check it out!

    David

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Sorry to give a NO NO on using such a small battery. Running amps would be over 12A on the battery each time a cloud comes over. The 400W panel will be fine for full sunshine.

    Further the starting current might go up to 1500W for a split second. Also that battery will just not make it. I am sure the Kill-A-Watt did not measure the peak due to it not reading every few milli seconds.

    Even if the 48Ah is a deep cycle you don't want to discharge more the 50% cycling every day. It might be fine to cycle say 20 times in it's life to 80% DOD. Even this is 80% is only 460Wh which is less than 3 hours if no sun.

    The inverter is also modified sine and not recommended. Rather look at the 1500/3000W pure sine as sold by Cobus RDW which you can find under the "Impressed with China pure sine wave inverter". Some friend have used the listed inverter on an induction motor on a fridge but only during LS. Not on a everyday basis.

    Once you have the panel and inverter you can try it at home and will see what period the battery can sustain the load from the fridge. It might disappoint you but rather before the time than get stuck.

    If you a DIY guy rather built a box and line it and the lid with 40-60mm polystyrene and keep say 2-3 x 2L coke bottles with frozen water. Such a box takes 3 times longer for the ice to turn to water than a house type fridge freezer compartment. I did the test with the cool box inside my caravan next to the double door KIC. Both were only opened the measure the quantity of water in the coke bottles.

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    How far is the next door neighbour ? When I built my house and could not get power untill the electricians could do their work I got friendly with the neighbour and he let me run an extension lead from his place to mine with a KWH meter and I just paid him double amount I used .

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Hi Ekkekan

    Thank you, your post is invaluable!

    I really like the idea of the cooler box, the only challenge would be refreezing the coke bottles (we are going for three weeks).

    For myself investing in the panels/inverter is significant at the moment so need to gather as much information as possible.

    Is it possible to not use a battery i.e. Solar Panels to inverter to fridge? Would the inverter simply not supply power if the demand was too great? Or would the fridge never start?

    Thank again for your post!

    Cheers

    David

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Quote Originally Posted by Andrew Rodrigues View Post
    How far is the next door neighbour ? When I built my house and could not get power untill the electricians could do their work I got friendly with the neighbour and he let me run an extension lead from his place to mine with a KWH meter and I just paid him double amount I used .
    Hi Andrew

    Now that is a great idea, I will ask!

    I have only seen photos from Google Maps satellite view and know the plot is 200m x 100m but their hous is going to be close to the boundary line so perhaps a 50m/100m extension could do the trick.

    David

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Quote Originally Posted by OceanWanderer View Post
    Hi Ekkekan

    Thank you, your post is invaluable!

    I really like the idea of the cooler box, the only challenge would be refreezing the coke bottles (we are going for three weeks).

    For myself investing in the panels/inverter is significant at the moment so need to gather as much information as possible.

    Is it possible to not use a battery i.e. Solar Panels to inverter to fridge? Would the inverter simply not supply power if the demand was too great? Or would the fridge never start?

    Thank again for your post!

    Cheers

    David
    David if the battery drops below 10.5Vthe inverter will just cut out to protect the batteries. Even if this drop is just for say 2 seconds.
    You can also use a large plastic tupper lunch box and buy a packet of ice daily. Or else use a large alu foil pan and put the ice in it.
    Getting power from a neighbour even 100m away is the better option. You can measure the power used and refund them.

    Some inverters will keep on trying to restart the fridge and destroy the battery drawing 150A each time.
    Others will stay off until you switch it off and on again.

    Also bear in mind with the fridge off during the night the 1st start in the morning will use a lot more power for starting.
    Last edited by ekkekan; 2021/09/27 at 11:13 AM.

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Would a 100ah battery and inverter do the trick? Just curious to know what would work.

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Hi Ekkekan

    Thank you, some wise words of wisdom!

    I think the polystyrene box is the way to go and top up with ice as suggested!

    Cheap and simple both of which I like!

    Cheers

    David

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    For the price of a pure sine inverter, why not have the fridge converted to a 12v compressor?
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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Hi Staalwol

    Open to all suggestions, I take it that some form of transformer would take the normal 220 back to 12v?

    For my holiday just a battery would be required and some form of charging?

    Cheers

    David

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Quote Originally Posted by DeVilliers View Post
    Would a 100ah battery and inverter do the trick? Just curious to know what would work.
    One can work on a max of 600Wh per 100Ah battery when discharged to 50% DOD. Then assume during the day you can replace that 600Wh with solar.

    I just ran a test during the weekend and a 90L chest freezer used 55W/H around the clock. No this load will just be too much for running from 16h00 to 09h00. Thus for 17 hours one will need 2 not allowing for cloudy days. This 220V chest freezer would draw 80W when it just switched on and then drop to 61W. It ran for about 80% of the time.

    Running from an inverter one will have to factor in say 15% losses.

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Quote Originally Posted by OceanWanderer View Post
    Hi Staalwol

    Open to all suggestions, I take it that some form of transformer would take the normal 220 back to 12v? If you want to run the fidge on 220v yes you wil
    l need a 12v power supply.

    For my holiday just a battery would be required and some form of charging? Yes like most people suggest 100ah battery, controller and solar panel, 100+watts.

    Cheers

    David
    Have a look at this video, guy is in Jhb, last time I contacted him was about R700 labour cost, not sure what 12v compressors cost theses days, guessing around R3000.
    https://www.youtube.com/watch?v=yK8X...lRefrigeration
    Last edited by staalwol; 2021/09/27 at 11:41 AM.
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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Not being the technical type yet will still say no as the battery and inverter are too pap.
    Loads of ice available in Langebaan.
    Less stress when the sea air comes over and the sun goes into hiding..
    There is no task too simple for some people to complicate !



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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Unfortunately there will simply be no shortcuts here.
    * Big enough battery 100 Ah plus.
    * Sine wave inverter highly recommended which will be able to handle the start up current as well.
    * Decent solar controller and enough panels which would be able to fully charge the battery every day.

    Not having gone in to the exact calculations I'd say even a 100 Ah deep cycle won't be enough, maybe a 100 Ah lithium.
    A Victron Phoenix 800VA inverter, the Victron's are pure sign wave and can truely handle peaks of double their rated capacity which is important for the startup current.
    Then 200 - 300W of solar panels or more with the appropriate controller.
    "The man who does not read has no advantage over the man who cannot read" - Not Mark Twain

  18. #17
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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Hi Duncan

    Thank you, I think you are quite right!

    Danie (Ekkekan) actually performed a test and a robust polystyrene box filled with ice has amazing staying power.

    After a quick search I see that there are two viable options a classic 20kg "fish box", by way of example (I found the manufacture and they are 25mm thick https://www.isowall.co.za/dt_portfol...-20-kg-deep/):
    https://www.bubblesplastics.co.za/pr...EaAov8EALw_wcB

    Or build my own using "R" rated 75mm polystyrene from these folk (https://www.polystyrene.co.za/online...rds-p211278503) - R600 for the highest density. Joint recommended is a butt joint which would be perfect to build a basic box with polystyrene glue!

    Drifting off the original topic, but I would once again appreciate any feedback/thoughts!

    Regards

    David

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Quote Originally Posted by OceanWanderer View Post
    Hi Duncan

    Thank you, I think you are quite right!

    Danie (Ekkekan) actually performed a test and a robust polystyrene box filled with ice has amazing staying power.

    After a quick search I see that there are two viable options a classic 20kg "fish box", by way of example (I found the manufacture and they are 25mm thick https://www.isowall.co.za/dt_portfol...-20-kg-deep/):
    https://www.bubblesplastics.co.za/pr...EaAov8EALw_wcB

    Or build my own using "R" rated 75mm polystyrene from these folk (https://www.polystyrene.co.za/online...rds-p211278503) - R600 for the highest density. Joint recommended is a butt joint which would be perfect to build a basic box with polystyrene glue!

    Drifting off the original topic, but I would once again appreciate any feedback/thoughts!

    Regards

    David
    Yes, soon the other solutions will cost more than a small power station
    There is no task too simple for some people to complicate !



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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Quote Originally Posted by bigboy529 View Post
    Unfortunately there will simply be no shortcuts here.
    * Big enough battery 100 Ah plus.
    * Sine wave inverter highly recommended which will be able to handle the start up current as well.
    * Decent solar controller and enough panels which would be able to fully charge the battery every day.

    Not having gone in to the exact calculations I'd say even a 100 Ah deep cycle won't be enough, maybe a 100 Ah lithium.
    A Victron Phoenix 800VA inverter, the Victron's are pure sign wave and can truely handle peaks of double their rated capacity which is important for the startup current.
    Then 200 - 300W of solar panels or more with the appropriate controller.
    Hopefully the 800VA Victron has a delay if it can provide 2 x for start current. A 150W running power fridge can use more than 1600W to start and perhaps close to 2000VA. Normally a 1000W inverter works fine. Smaller than that works sometimes but does give failed starts.

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    Default Re: Help On Running a 220v Fridge on an Inverter/Solar Setup

    Quote Originally Posted by ekkekan View Post
    Hopefully the 800VA Victron has a delay if it can provide 2 x for start current. A 150W running power fridge can use more than 1600W to start and perhaps close to 2000VA. Normally a 1000W inverter works fine. Smaller than that works sometimes but does give failed starts.

    I can run the upright fridge in the house or the upright freezer or the medium sized chest freezer on a Victron 1200VA, I've done this plenty times in the past and not one of the 3 is modern appliances, I doubt they are even A energy rated.
    OP said his fridge pulls 150W while running and 400W on startup, even if it pulls 1200W (3x that) for a few milliseconds the Phoenix 800VA will be just fine.

    While the fridge is running on the 1200VA I however can't add the freezer, then the start up current is too much and it goes in to overload.
    Last edited by bigboy529; 2021/09/27 at 01:12 PM.
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