Small Low-Cost Off-Grid Solar System - Page 2





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  1. #21
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    Default Re: Small Low-Cost Off-Grid Solar System

    My requirements are similar to the ones discussed in this forum (with the exception of washing washing):

    https://www.4x4community.co.za/forum...idge-off-solar

    Fluffy made the recommendations shown in the picture, any comments on that?
    Attached Images Attached Images  

  2. #22
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    Default Re: Small Low-Cost Off-Grid Solar System

    So I got this spreadsheet from powerforum.co.za

    It support my calculations and Fluffy's suggestion for 12V 4x100Ah batteries or 2x 200Ah batteries for a 24 V system. What are the ideal parameters for "battery aging and lose wire/connectors" values? They seem to dramatically increase the required number of batteries depending on what you input. For example if I put both values at 0%, the required battery bank is 130 Ah which is 2 batteries, if I put them both at 20% battery bank size increase to 187 Ah or 4 batteries.
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  3. #23
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by VVTi View Post
    Yes this can definitely work.


    The battery, https://lithiumbatteriessa.co.za/col...32321358954586

    The rest of my pricing was just shooting from the hip.
    It's in pubs where the world's greatest ideas begin.

  4. #24
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by bigboy529 View Post
    Thanks.

  5. #25
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by VVTi View Post
    So I got this spreadsheet from powerforum.co.za

    It support my calculations and Fluffy's suggestion for 12V 4x100Ah batteries or 2x 200Ah batteries for a 24 V system. What are the ideal parameters for "battery aging and lose wire/connectors" values? They seem to dramatically increase the required number of batteries depending on what you input. For example if I put both values at 0%, the required battery bank is 130 Ah which is 2 batteries, if I put them both at 20% battery bank size increase to 187 Ah or 4 batteries.
    Mmm, wonder where they go that Excel. Probably from a Guest user.

    Leave those defaults, as you are getting new batts.
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  6. #26
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by the_terrible_triplett View Post
    Mmm, wonder where they go that Excel. Probably from a Guest user.


    Leave those defaults, as you are getting new batts.
    I got an updated spreadsheet here:
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by VVTi; 2020/06/29 at 07:00 PM.

  7. #27
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by the_terrible_triplett View Post
    Mmm, wonder where they go that Excel. Probably from a Guest user.

    Leave those defaults, as you are getting new batts.
    The author has a blog and has written 100's of articles explaining things around electrics. He knows a thing or 2 about what he writes.

  8. #28
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    Default Re: Small Low-Cost Off-Grid Solar System

    Your proposed 12v system can work for the proposed loads, minus the washing machine. The large fridge may also need to be replaced by a dual input camping fridge.

    When starting out off grid, your system design revolves around the spec's and consumption of your appliances, so decide and work on this first.

    A 10-15amp battery charger and small generator would be very wise addition and could power the washing machine with any other occasional / heavier load.

  9. #29
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by VVTi View Post
    My requirements are similar to the ones discussed in this forum (with the exception of washing washing):

    https://www.4x4community.co.za/forum...idge-off-solar

    Fluffy made the recommendations shown in the picture, any comments on that?
    I will take a different approach as far as the inverter is concerned. Using the low cost 24V 2000W with 4000W peak pure sine imported from China on the banggood.com web site. Bear in mind this price is only for the next 6 days.
    https://www.banggood.com/Intelligent...r_warehouse=CN
    This can be matched with a good MPPT 135-150V/30-35A controller.
    Click image for larger version. 

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    Panels have already been taken care of.

    The Samsung Top Loader washing machine only uses 330W and can be run on 1 x 12V 100Ah battery while the sun is shining. This is what we did when I bought my 1st solar panel and used a 1000W inverter I had been using for quite a few years.

    On this topic there are may be 50 guys who can give a reference to this inverter we bought from Dec 2019. Take a day to read the 955 comments on this placement I started.
    https://www.4x4community.co.za/forum...-Wave-Inverter

    The 2000/4000W cheap inverter would run the 700W while idling. Also great that this inverter has no fan running below about 350W. The fan is tied to the load and not to temperature.

    Yes an Axpert does have everything inside one box and might be cheaper than buying a controller and inverter.

    I do belief your 1150Wh from 2 x 330W panels per day is far too low. 2500Wh is more of a daily average and already on the low side and can go as high as 3000Wh. This is for a Gauteng install. Not sure in which part of the country your Mom is staying.

    My 2c on this topic.
    Last edited by ekkekan; 2020/06/29 at 09:32 PM.

  10. #30
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by rnieckau View Post
    Your proposed 12v system can work for the proposed loads, minus the washing machine. The large fridge may also need to be replaced by a dual input camping fridge.

    When starting out off grid, your system design revolves around the spec's and consumption of your appliances, so decide and work on this first.
    One can also look at using 1 more panel (R1 800) for house type fridges instead of spending like R8 000 for a low power inverter fridge. I just did a test over the weekend and found my 210L freezer ran for 18 hours on 2 x 100Ah well used batteries. Batteries were at 12V after the 18 hours. I have to stress that it was never opened during this time. My Samsung bar fridge uses 600Wh per 24 hours so one can get along with a small fridge instead of going the camping fridge route which is expensive to buy (budget) although economical on power.

  11. #31
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by ekkekan View Post
    On this topic there are may be 50 guys who can give a reference to this inverter we bought from Dec 2019. Take a day to read the 955 comments on this placement I started.
    https://www.4x4community.co.za/forum...-Wave-Inverter
    I spent many nights following this thread



    Quote Originally Posted by ekkekan View Post
    I do belief your 1150Wh from 2 x 330W panels per day is far too low. 2500Wh is more of a daily average and already on the low side and can go as high as 3000Wh. This is for a Gauteng install. Not sure in which part of the country your Mom is staying.

    My 2c on this topic.
    Thanks for pointing that, I made a mistake, the expected yield for one panel is 1122 Wh using irradiation of 4 and inverter efficiency of 85%, total yield for two panels is ~2300 Wh which in line with your estimation. My mom is staying in northern Gauteng.
    Last edited by VVTi; 2020/06/30 at 12:40 AM.

  12. #32
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    Default Re: Small Low-Cost Off-Grid Solar System

    Faniedup gets about 5kWh/kW installed PV in Pta. My actual is close to 4kW/kW installed. I found efficiency is perhaps higher than what we see calculated figures indicate.

  13. #33
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by ekkekan View Post
    One can also look at using 1 more panel (R1 800) for house type fridges instead of spending like R8 000 for a low power inverter fridge. I just did a test over the weekend and found my 210L freezer ran for 18 hours on 2 x 100Ah well used batteries. Batteries were at 12V after the 18 hours. I have to stress that it was never opened during this time. My Samsung bar fridge uses 600Wh per 24 hours so one can get along with a small fridge instead of going the camping fridge route which is expensive to buy (budget) although economical on power.
    Thats why I suggest the ac/dc camping fridge, low power requirements and no conversion and running losses by an inverter.

    18 hours is very good, dont think those well used bats are doing too badly.

  14. #34
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    Default Re: Small Low-Cost Off-Grid Solar System

    Quote Originally Posted by rnieckau View Post
    Thats why I suggest the ac/dc camping fridge, low power requirements and no conversion and running losses by an inverter.

    18 hours is very good, dont think those well used bats are doing too badly.
    Yes it was a matter of 2nd time lucky with 2nd hand batteries. In Jan I bought some great batteries that I thought trying to help someone who relocated to CT and did not want to move with his 6 month old hardly used Deltecs. I only tested to what I thought was 50% DOD down to 12V under a 4.5A load. It took 5 hours. I then bought them. The 1st time I took them down to 11.8V they just collapsed to 10.5V within 10 min after getting to 12V and they did the same at other times. Then I got approached by a battery dealer and he indicated he had 40 x well used batteries but they are in good condition. Well thats how I bought 2 and as things happen in life the make is the last make I would ever buy if I had to buy new batteries.

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