Taking our SOHO off grid





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  1. #1
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    Default Taking our SOHO off grid

    This thread, among others, refers:

    https://www.4x4community.co.za/forum...verter-Sesteem

    SOHO spec:

    - self contained cottage style building
    - separate feed from main DB with own sub DB
    - no geysers
    - Neon lights and energy savers
    - 1 x aircon (12,000BTU inverter)
    - WiFi router and receiver mast
    - wall plugs for laptops and possibly some desktops
    - kettle
    - coffee machine

    So I assume STEP ONE is a peak load identification?
    Jakes Louw
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  2. #2
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    Default Re: Taking our SOHO off grid

    Yup.
    Just get this and the guessing and Q&A speculative answers is no longer.

    https://www.ellies.co.za/product/efe...gy-monitor-e2/

    Export to spreadsheet, graphs, etc.
    I have mine set to cost/kW.

    Just.Do.It!
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  3. The Following 3 Users Say Thank You to swakop_toe For This Useful Post:


  4. #3
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    Default Re: Taking our SOHO off grid

    Good advice. Will have to find a local branch for that.
    Jakes Louw
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  5. #4
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    Default Re: Taking our SOHO off grid

    Builders stock them too.
    And they deliver.

    https://www.builders.co.za/Electrica...00000000492466
    '00 Nissan D22 QD32Ti 4x4 D/C
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    Our lives were governed by the Ten Commandments, good judgment, and common sense.

  6. #5
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by swakop_toe View Post
    Builders stock them too.
    And they deliver.

    https://www.builders.co.za/Electrica...00000000492466
    thanks

    I'd rather go fetch. Massmart couriers are terrible.
    Jakes Louw
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  7. #6
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by swakop_toe View Post
    Builders stock them too.
    And they deliver.

    https://www.builders.co.za/Electrica...00000000492466
    Very nice unit - old school turning kWh meter are available for below R300. I installed 2 recently.

  8. #7
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by ekkekan View Post
    Very nice unit - old school turning kWh meter are available for below R300. I installed 2 recently.
    This logs all the data and you download it.
    Sent both the past off-grid stats to SolarEFF to size and quote the systems based on one full year's worth of data.
    This will size your inverter and solar panels.
    Add to 10% growth, decide how long you can hold out on batteries without a charge and generator to size the battery capacity and you have a calculated, measured system based on facts, no guessing.
    '00 Nissan D22 QD32Ti 4x4 D/C
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  9. #8
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    Default Re: Taking our SOHO off grid

    Well I reckon I'll just over-size the solution and not worry later when we have a week of cloud.........

    - 8 x neon 4' strips = 640W
    - 10 x 14W energy saver = 140W
    - 60W + 40W security lights = 100W
    - 2 x laptops = 190W
    - 120,000BTU aircon = 2500W
    - kettle / coffee maker = 1200W
    - 2 x LED 32" screens = 100W
    - 1 x Canon colour printer = 10W

    So around 5kW at peak draw.

    I see that a general rule of thumb is 20-25% more to accommodate any surge?

    So let's say a 7kW peak load with surge.

    am I on the right track?
    Jakes Louw
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  10. #9
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    Default Re: Taking our SOHO off grid

    So according to a couple of online sizers:

    5kW is confirmed

    32.5kwH per day

    So for a 3 day storage:

    Minimum system size: 6kW inverter
    Number of solar panels: 17 x 330wp panels
    Total battery amperage required: 2752 Amp hours
    Minimum Regulator Size: (MPPT ONLY) 125 Amp

    So that is 108 x 105aH batteries

    This sounds excessive.
    Jakes Louw
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  11. #10
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by jelo View Post
    Well I reckon I'll just over-size the solution and not worry later when we have a week of cloud.........

    - 8 x neon 4' strips = 640W How long on for?
    - 10 x 14W energy saver = 140W How long on for?
    - 60W + 40W security lights = 100W How long on for?
    - 2 x laptops = 190W
    - 120,000BTU aircon = 2500W How long on for?
    - kettle / coffee maker = 1200W One of those percolators that's on during office hrs?
    - 2 x LED 32" screens = 100W
    - 1 x Canon colour printer = 10W Does it have standby consumption spec?

    So around 5kW at peak draw.

    I see that a general rule of thumb is 20-25% more to accommodate any surge?

    So let's say a 7kW peak load with surge.

    am I on the right track?
    Note all my questions are time related.....gives a better picture of your usage converted to kWh

    Will do calc from that for you
    Robert van den Berg

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  12. #11
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    Default Re: Taking our SOHO off grid

    With Victron MPPT and Inverter, ±R180k.
    But I'm sure Fluffy will be along shortly to prove me incorrect.

    Leave the air-conditioning and kettle out of the equation.
    You'll have a massive reduction.
    Last edited by swakop_toe; 2019/03/19 at 10:55 AM.
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  13. #12
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    Default Re: Taking our SOHO off grid

    6kW inverter : R18k
    https://www.pricecheck.co.za/offers/...+Wave+Inverter

    17 x 330wp panels : R34k
    https://www.sustainable.co.za/canadi...lar-panel.html

    MPPT charge controller: R15k
    https://www.sustainable.co.za/victro...ontroller.html


    108 x 105aH batteries : R378k

    Something tells me I need to rethink my storage needs.......
    Jakes Louw
    2012 Jeep Sahara Unlimited 3.6 V6
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  14. #13
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by Prof View Post
    Note all my questions are time related.....gives a better picture of your usage converted to kWh

    Will do calc from that for you
    - 8 x neon 4' strips = 640W How long on for? 9 hours
    - 10 x 14W energy saver = 140W How long on for? 24 hours
    - 60W + 40W security lights = 100W How long on for? 8 hours: day/night ambient light switch
    - 2 x laptops = 190W 10 hours
    - 120,000BTU aircon = 2500W How long on for? 3 hours
    - kettle / coffee maker = 1200W One of those percolators that's on during office hrs? yes but usually only on while there is coffee so 2-3 hours max
    - 2 x LED 32" screens = 100W 10 hours
    - 1 x Canon colour printer = 10W Does it have standby consumption spec? 1W

    As above.

    Neons can be switched off after hours, so let's say realistically 9 hours per day
    The energy savers will stay on.
    Jakes Louw
    2012 Jeep Sahara Unlimited 3.6 V6
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  15. #14
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by swakop_toe View Post
    Leave the air-conditioning and kettle out of the equation.
    You'll have a massive reduction.
    nope, want a complete off grid solution with full normal operation

    NB: THIS IS A HOME OFFICE: daylight usage only. So I can up-spec on the SOLAR PV for daytime power generation, and consequently reduce the initial batteries to maintain night-time standby usage only in the first phase.
    Jakes Louw
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by jelo View Post
    Well I reckon I'll just over-size the solution and not worry later when we have a week of cloud.........

    - 8 x neon 4' strips = 640W - Retrofit T8 LEDs - 8x14W = 112W
    - 10 x 14W energy saver = 140W - Replace with LED lamp - 10x3W = 30W
    - 60W + 40W security lights = 100W - Replace fittings with 2x10W LED floddlights - 20W
    - 2 x laptops = 190W
    - 120,000BTU aircon = 2500W - Leave out
    - kettle / coffee maker = 1200W - Use gas
    - 2 x LED 32" screens = 100W
    - 1 x Canon colour printer = 10W

    So around 5kW at peak draw.

    I see that a general rule of thumb is 20-25% more to accommodate any surge?

    So let's say a 7kW peak load with surge.

    am I on the right track?
    See above, leave the coffee machine and AC off the system, and replace lamps or fittings with LED, and you're down to under 500W, or about 6kWh for a 12 hour day.

    For 50% DoD, you'd need about 20x105ah batteries in a 48V system - ±R50k vs R270 000 for the 108 if you need to run the large consumers. Inverter can suddenly be a 1kW VS 6-7KW, and you could keep the amount of solar panels or reduce slightly still have a decent buffer for the cloudy low yield days. Now you're looking at closer to R100k all in than R5-600K.

    Is an AC worth R4-500k capital cost to the business?
    Office Johnny

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  17. #16
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by petermoffat View Post
    Is an AC worth R4-500k capital cost to the business?
    DAMN yeah. Come to North West and see.
    Jakes Louw
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  18. #17
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by jelo View Post
    - 8 x neon 4' strips = 640W How long on for? 9 hours
    - 10 x 14W energy saver = 140W How long on for? 24 hours
    - 60W + 40W security lights = 100W How long on for? 8 hours: day/night ambient light switch
    - 2 x laptops = 190W 10 hours
    - 120,000BTU aircon = 2500W How long on for? 3 hours
    - kettle / coffee maker = 1200W One of those percolators that's on during office hrs? yes but usually only on while there is coffee so 2-3 hours max
    - 2 x LED 32" screens = 100W 10 hours
    - 1 x Canon colour printer = 10W Does it have standby consumption spec? 1W

    As above.

    Neons can be switched off after hours, so let's say realistically 9 hours per day
    The energy savers will stay on.
    They are not all going to surge at the same time. Even if they do most inverters have a 100% overload surge capacity anyway.

    Don't be tempted to play with 1kW toys and 12V systems. We live on the edge in so many ways already in this country, don't add another one.
    Cheers

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  19. #18
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    Default Re: Taking our SOHO off grid

    - 8 x neon 4' strips = 640W - Retrofit T8 LEDs - 8x14W = 112W
    Good idea, thanks

    - 10 x 14W energy saver = 140W - Replace with LED lamp - 10x3W = 30W
    Ditto


    - 60W + 40W security lights = 100W - Replace fittings with 2x10W LED floddlights - 20W
    Nope, not negotiable on a farm

    - 120,000BTU aircon = 2500W - Leave out
    Not a chance

    - kettle / coffee maker = 1200W - Use gas
    Yes, currently heating water on the gas hob during load shedding

    See my comment regarding DAILY PV GENERATION versus STORAGE. I don't mind a few more panels.

    I'll compare the various batteries and see what gives the best bang per buck when it comes to DoD and AH.

    But I'm thinking that for phase 1 I would look at a day/night load split and accommodate the nightly load only on storage batteries.

    Night load will be around 500W as most stuff will be off/on standby/on hibernate. So around 6kWh as you mention.
    Jakes Louw
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  20. #19
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    Default Re: Taking our SOHO off grid

    Quote Originally Posted by Fluffy View Post
    They are not all going to surge at the same time. Even if they do most inverters have a 100% overload surge capacity anyway.

    Don't be tempted to play with 1kW toys and 12V systems. We live on the edge in so many ways already in this country, don't add another one.
    Are you saying a 6kW inverter is overkill?
    Jakes Louw
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  21. #20
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    Default Re: Taking our SOHO off grid

    Can someone advise the life expectancy of the batteries, A friend has a wind generator and his batteries last 5-6 years, he replace batteries last year at a cost of nearly R150,000.

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