What pumps to go for with solar in mind





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  1. #1
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    Default What pumps to go for with solar in mind

    Hi guys.
    I currently have a 3 phase multistage Aspri25 pump (0.75hp), pumping water from the Jojo tank to our house and a 3 phase borehole pump (80m deep and 100m of pipe running above ground to the tank). We are looking at our journey towards going solar (grid-tied) and the first steps I think would need to be to get the borehole pump and the pressure pumps to a workable setup for solar.
    What would you suggest for a solar borehole pump and then what should I look at replacing the 3 phase booster pump with? If I look at the math it will be cheaper and better to replace the borehole and booster pumps with single phase units rather than trying to keep them 3 phase and converting them to solar.
    I see Bundupower have a 48v booster pump but it seems expensive and you must run it either with solar or a genie with a manual switchover, which is not ideal. There seems to be miriad of options from multistage pumps to self priming to vsd pumps, but Im unsure of what is best for my situation. Our current setup is on demand, if you open a tap, the pump kicks in and you have water.

    Thanks in advance.

  2. #2
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    Default Re: What pumps to go for with solar in mind

    In order to look at options one needs to know what is the size of the 3 phase borehole pump. As booster pumps are not expensive that can be run on solar/batteries but not on a grid tied only inverter as the pump would need to work a bit while there is no sun. Need would be to go the hybrid route to lower grid useage during the day. Also one would need to measure the power used per week/month to calculate the size of the batteries. One could also just use a cheap hour meter to know how many hours it is running per week/month.

    Also what is the distance to the borehole from the house to look at positioning of equipment and cabling to be used if panels/inverters are centralised. Cabling is a major expense if long distances.

  3. #3
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    Default Re: What pumps to go for with solar in mind

    I am complete off-grid. I had a 3 phase 3kW borehole pump which I replaced with a 1.1 kW single phase Franklin pump. Borehole is 40m deep and I run it to a tank about 60m away. As Ekkekan said, your depth of borehole and distance to tank with pipe diameter will determine your pump size.

    For my pressure pump I have a cheap 0.75kW jobbie from WaterWare/SAPlasticor.

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    Default Re: What pumps to go for with solar in mind

    Depending on the size of borehole pump you have, you could just change to a single phase VSD.
    Only thing you have to double check is the voltage on the motor, as the VSD will give you 230V 3ph and not 400V 3ph.
    Still the most cost effective solution to replacing the pump motor.

    To go with a complete separate solar system just for the borehole is not really worth it.
    It would be a huge investment that only runs couple of hours per day.

    If you really set on solar, rather look at a system that can supply power to the complete house. That would save you more money in the longer term.


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  5. #5
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    Default Re: What pumps to go for with solar in mind

    Thanks for the replies guys. Any recommendations for where to look for pumps and vsd/solar systems?
    My borehole pump is 80m deep and then the pipe runs 100m horizontally to the Jojo tank. Its a 50mm pipe. Solar will work well even if its just for the borehole pump to pump water into the tanks when the sun shines, we have never used the 5000l tank in 1 day so I'm sure 3-4 hours of sunlight will be able to keep the tanks full enough.
    The pressure pump is a Aspri25 ESPA 3 phase which is 0.75hp if that helps?

  6. #6
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    Default Re: What pumps to go for with solar in mind

    Convert all to single-phase and invest in 5kva+ decent inverter & some panels. Water is life so batteries are part of my oqaution.
    Quote Originally Posted by Toeks View Post
    Thanks for the replies guys. Any recommendations for where to look for pumps and vsd/solar systems?
    My borehole pump is 80m deep and then the pipe runs 100m horizontally to the Jojo tank. Its a 50mm pipe. Solar will work well even if its just for the borehole pump to pump water into the tanks when the sun shines, we have never used the 5000l tank in 1 day so I'm sure 3-4 hours of sunlight will be able to keep the tanks full enough.
    The pressure pump is a Aspri25 ESPA 3 phase which is 0.75hp if that helps?
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    Default Re: What pumps to go for with solar in mind

    Quote Originally Posted by Toeks View Post
    Thanks for the replies guys. Any recommendations for where to look for pumps and vsd/solar systems?
    I used to buy Grundfos sqf solar pumps only, good but become very expensive. Recently bought a multiflow from https://www.cedarsolar.com/products-solar-water-pumps/. Cheaper, with 3 separate parts that can be replaced individual.
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  8. #8
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    Default Re: What pumps to go for with solar in mind

    Quote Originally Posted by Toeks View Post
    My borehole pump is 80m deep and then the pipe runs 100m horizontally to the Jojo tank. Its a 50mm pipe. Solar will work well even if its just for the borehole pump to pump water into the tanks when the sun shines, we have never used the 5000l tank in 1 day so I'm sure 3-4 hours of sunlight will be able to keep the tanks full enough.
    The Wortex WOST25-16 16 stage pump @ 1.5kW can provide a head of 98m and deliver 2100L/h(35L/min). This pump is available for R1 300 on line. I just don't know if it is single or 3 phase. If 3 phase then the option to add a VSD comes into play. At a head of 86m the delivery goes up to 3600L/h.

    As you have indicated you want to go grid tied you can get away with 6 x 330W (R2 000 each) panels and a Solis 2kW grid tied inverter for R7 850. During the 4-5 hours period of sun it should provide enough water to your tank. Being grid tied if there is no sun you just draw power from the grid to supplement to get 1.5kW to the pump. Outside of the 5 hours peak PV you still get a contribution from PV with reduced grid useage. These panels might also provide some power for fridges during sun periods and saving grid power without the expense of batteries that have a specific life cycle if used every day.

    The same panels could perhaps feed the pressure pump if you perhaps find that you only need 2 hours running of the borehole per day. As the pressure pump is needed on demand it is perhaps difficult to run both from the same panels.

    The info is just a starting point if you want to go the solar route. I would think it is not very practical to use a battery system for this set-up but those using solar could be in a better position to give guidance.
    Last edited by ekkekan; 2020/06/17 at 08:02 PM.

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