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  1. #1
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    Default Not grid tied, solar when the sun shines

    Hi All

    I need some guidance please.

    I want to get an inverter and some panels to run my borehole and geyser during the day when the sun shines. I guess I need to route this to a new DB board?

    My requirement is not to save money, rather to 'almost' always be able to run this irrespective of Eskom availability.

    It would be great if my setup can be expanded at a later stage to include batteries for night lights, and to add more panels to run washing machine, laptop chargers etc during the day.

    Will this inverter be a decent buy taking the above into consideration?

    https://shop.thesunpays.co.za/produc...RoC3ToQAvD_BwE

    If there is something better suited for my needs out there please let me know, but keep in mind 'I dont want to buy a tractor just to cut a townhouse garden's grass'
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  2. #2
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    Default Re: Not grid tied, solar when the sun shines

    You will require quite a hefty inverter and solar panel setup to run your borehole and geyser simultaneously. Is the borehole feeding an inverted tank?

    What will happen on cloudy days? You will have about 20% efficiency then.

    Much more thought needs to be going into your thinking.
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  3. #3
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    Default Re: Not grid tied, solar when the sun shines

    No need to run both simultaneously.

    On cloudy days we can use the gas geyser in the other bathroom and dont need to run the borehole everyday. That is why I said only run when the sun shines. On days when the sun doesnt shine enough we dont run it.

    The boreholes feeds into a jojo.
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  4. #4
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    Default Re: Not grid tied, solar when the sun shines

    Depending on borehole pump electric draw it will work. My borehole draws about 1kW, and a standard 200L geyser use a 4kW element. I would swop the element for a 2kW unit as you have all day to heat it up, Mine runs for about 4hrs a day to get to 65C with a 2kW element. That will also leave you some headroom should you get cloudy days without battery backup.

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  6. #5
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    Default Re: Not grid tied, solar when the sun shines

    Die Uwe, i went thru a very similar exercise. I initially wanted to run my pool and heat pump which drivers the geysers on solar. Just those two add up to a 2.5kw load which is on 3 hours a day. You would need 8 x 400W panels, less 20% = 2.5kw. You would need an inverter, lets say 3.5kw at 10k give or take. Lets call it 30k without other actual install costs. Seeing as your projected loads are higher you would need more power. If you can swop for a smaller element that would help. My original budget was 40k, i ended at 65k but now the whole house runs on the 9 x panels [when its sunny 😁]. On some days i feed back 5kw back to the grid. Not entirely sure how you would have this as a stand alone, instead of thru db / grid tie or non grid tie.

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  8. #6
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    Default Re: Not grid tied, solar when the sun shines

    Ok, you have a problem then.

    Not a bad unit for the price.
    How it will actually work without batteries, could be a problem.
    Yes, you do get units that can work that way, but then you need to make sure that you have WAY more solar PV connected than your load you will draw.
    The geyser might actually be fine, as that is a pure resistor, but the pump motor might be a problem.
    Motors can draw up to 8 times their rated current on start-up. If there is only PV, where would the extra power come from?

    But it is a good start.

    P.S.
    I see you in Cape Town.
    Please make 100% sure your inverter is on the list of accepted units. If not, you might have issues registering.
    Bypass the registration at your own peril.
    A friend got fined R8,5k the other day and had his power cut due to "illegal" solar system.
    Last edited by Wetkit; 2021/07/29 at 01:19 PM.


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  10. #7
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    Default Re: Not grid tied, solar when the sun shines

    Not a bad unit at that price, it should work - but advised to add the minimum batteries from the start
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  12. #8
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by Wetkit View Post
    Ok, you have a problem then.

    Not a bad unit for the price.
    How it will actually work without batteries, could be a problem.
    Yes, you do get units that can work that way, but then you need to make sure that you have WAY more solar PV connected than your load you will draw.
    The geyser might actually be fine, as that is a pure resistor, but the pump motor might be a problem.
    Motors can draw up to 8 times their rated current on start-up. If there is only PV, where would the extra power come from?

    But it is a good start.

    P.S.
    I see you in Cape Town.
    Please make 100% sure your inverter is on the list of accepted units. If not, you might have issues registering.
    Bypass the registration at your own peril.
    A friend got fined R8,5k the other day and had his power cut due to "illegal" solar system.
    Is there still a problem in Cape Town if you are not grid tied. The proposed system is essentially a solar assisted UPS.
    Cheers

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  13. #9
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by Die Uwe View Post
    Hi All

    I need some guidance please.

    I want to get an inverter and some panels to run my borehole and geyser during the day when the sun shines. I guess I need to route this to a new DB board?

    My requirement is not to save money, rather to 'almost' always be able to run this irrespective of Eskom availability.

    It would be great if my setup can be expanded at a later stage to include batteries for night lights, and to add more panels to run washing machine, laptop chargers etc during the day.

    Will this inverter be a decent buy taking the above into consideration?

    https://shop.thesunpays.co.za/produc...RoC3ToQAvD_BwE

    If there is something better suited for my needs out there please let me know, but keep in mind 'I dont want to buy a tractor just to cut a townhouse garden's grass'
    The problem is that you may be buying a Tractor to water the garden.
    Cheers

    ZS5KAD - PROFFESIONAL DUMBASS
    3 Land Rover V8's
    NA - TwinTurbo - SuperCharged
    A V6 and an inline 4

    If you fly or drive to an anti-Fracking meeting, you have no business being there and you wont get my ear......

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  15. #10
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    Default Re: Not grid tied, solar when the sun shines

    Just go grid tied and be done.
    Jakes Louw
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  16. #11
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by Kamakazi View Post
    Not a bad unit at that price, it should work - but advised to add the minimum batteries from the start
    Agree 1000%. An analogy would be using a windpump to water your fields without a reservoir. As the wind waxes and wanes the water pressure and flow rate will be all over the place. (In an inverter this phenomena is even much worse as the system thresholds are momentarily reached and the breached)

    Much better to use the pump to fill a reservoir and then feed from that.

    You don't have to empty the reservoir every time you use it. Just use it as a smoothing buffer.
    Last edited by Fluffy; 2021/07/29 at 02:15 PM.
    Cheers

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    If you fly or drive to an anti-Fracking meeting, you have no business being there and you wont get my ear......

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  18. #12
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by jelo View Post
    Just go grid tied and be done.

    Why?
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  19. #13
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by Fluffy View Post
    Agree 1000%. An analogy would be using a windpump to water your fields without a reservoir. As the wind waxes and wanes the water pressure and flow rate will be all over the place. (In an inverter this phenomena is even much worse as the system thresholds are momentarily reached and the breached)

    Much better to use the pump to fill a reservoir and then feed from that.

    You don't have to empty the reservoir every time you use it. Just use it as a smoothing buffer.

    That was my idea when I first thought about it. Later on I thought I might use that money better by adding it to solar panels.
    What batteries would you recommend to kickstart this off?
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  20. #14
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    Default Re: Not grid tied, solar when the sun shines

    I was going to agree with Jelo but then i read what the OP originally said:

    My requirement is not to save money, rather to 'almost' always be able to run this irrespective of Eskom availability

    If its not about saving money, then i am sure allot on this forum can advise. You will need a bunch of panels, big battery, like
    Fluffy said, in a way, a massive UPS. The capacity has to be enough, between 3kw and 4kw perhaps at a guess?

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  22. #15
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    Default Re: Not grid tied, solar when the sun shines

    A question: Can you use DC directly from a solar panel to heat an element, bypassing the inverter?
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  23. #16
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by Die Uwe View Post
    Why?
    How are you going to guarantee a 1kW feed to the pump motor without a battery buffer?

    If the pump and the geyser both run and exceed the available SOLAR POWER, the inverter will trip.

    If you want this to work ONLY on solar, then you can only use either the pump OR the geyser and ONLY if you are supplying the inverter with much more than the load draw or requirement.

    The big solar panels are 595W each at the moment: JUST the pump will need 2 x panels minimum as you never get 100% output. Safer would be 3 panels.

    But your inverter needs 280-360Vdc solar input. A 595W Canadian put out 40vdc. Oops. You now need 7 panels minimum. So then you need to balance voltage to watts.

    So let's say 440W panels. 7 x 440 = 3kW. Not enough for your geyser. 10 is just enough, but now you're almost over your input limit on the inverter.

    Panels alone: R25k
    Inverter: R10k
    Wiring and frames: R5k

    R40k to save what? 5kWh per day ? 150kWh @ R2.60 = R375 per month. 9 years to break even?
    Jakes Louw
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  24. #17
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by ezee rider View Post
    I was going to agree with Jelo but then i read what the OP originally said:

    My requirement is not to save money, rather to 'almost' always be able to run this irrespective of Eskom availability

    If its not about saving money, then i am sure allot on this forum can advise. You will need a bunch of panels, big battery, like
    Fluffy said, in a way, a massive UPS. The capacity has to be enough, between 3kw and 4kw perhaps at a guess?

    That is the idea yes. I wasnt aware of the 8x normal kw on a borehole pump startup. If that is indeed true and my borehole pump is 1.5kw as I suspect, then I will hae no choice but getting the batteries from the start.
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  25. #18
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by jelo View Post
    How are you going to guarantee a 1kW feed to the pump motor without a battery buffer?

    If the pump and the geyser both run and exceed the available SOLAR POWER, the inverter will trip.

    If you want this to work ONLY on solar, then you can only use either the pump OR the geyser and ONLY if you are supplying the inverter with much more than the load draw or requirement.

    The big solar panels are 595W each at the moment: JUST the pump will need 2 x panels minimum as you never get 100% output. Safer would be 3 panels.

    But your inverter needs 280-360Vdc solar input. A 595W Canadian put out 40vdc. Oops. You now need 7 panels minimum. So then you need to balance voltage to watts.

    So let's say 440W panels. 7 x 440 = 3kW. Not enough for your geyser. 10 is just enough, but now you're almost over your input limit on the inverter.

    Panels alone: R25k
    Inverter: R10k
    Wiring and frames: R5k

    R40k to save what? 5kWh per day ? 150kWh @ R2.60 = R375 per month. 9 years to break even?

    Please read my OP again. I dont want this setup to be reliant on Eskom. The answer then is not go grid tied. The answer is add batteries.

    I dont care about break even. Break even calculations is not going to help me anything if worst case scenario, Eskom is unavailable for days on end
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  26. #19
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    Default Re: Not grid tied, solar when the sun shines

    Quote Originally Posted by ezee rider View Post
    I was going to agree with Jelo but then i read what the OP originally said:

    My requirement is not to save money, rather to 'almost' always be able to run this irrespective of Eskom availability

    If its not about saving money, then i am sure allot on this forum can advise. You will need a bunch of panels, big battery, like
    Fluffy said, in a way, a massive UPS. The capacity has to be enough, between 3kw and 4kw perhaps at a guess?
    Yes, you need to take the pump and geyser off grid and have an off-grid system with panels and batteries.
    That means NOT running the pump or geyser off solar, but off battery and these are recharged later or even in parallel.

    5kWh = a BUNCH of deep cycle batteries with battery protection. Not so simple.
    Jakes Louw
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  27. #20
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    Default Re: Not grid tied, solar when the sun shines

    Just to add. The pump and the geyser dont have to run at the same time. I dont plan on pumping water out of the ground for 6 hours a day.
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