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Thread: Need to lift water 3m, will solar pump work?

  1. #1

    Default Need to lift water 3m, will solar pump work?

    Hi
    I need to lift water 3m. Will a solar pump work? The volume is about 50 liters/day.

    First, what size (w) pump will I need? Secondly, will I be able to do it with solar?

    I have seen solar powered fishpond pumps but I don't think they will be able to provide the 'lift'.

  2. #2

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    Research submersible water pumps.

    From Wiki http://en.wikipedia.org/wiki/Submersible_pump

    The main advantage of this type of pump is that it prevents pump cavitation, a problem associated with a high elevation difference between pump and the fluid surface. Submersible pumps push fluid to the surface as opposed to jet pumps having to pull fluids. Submersibles are more efficient than jet pumps.
    You might be able to find a low powered one that you can attach to a battery with a solar panel to charge it.

    Maybe this ? http://www.waterpumps.co.za/product_...mersible-p-188
    Last edited by ITCynic; 23-03-2012 at 11:50 PM.

  3. #3
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    This is down to the numbers: you already know you want to do 50l/day (which is incomplete data: in what time frame do you plan to do the lifting?) and you know you have a 3m head ('head' is the term here for height you have to lift). Now you just have to factor in how much juice you're going to get from your panel (array...). Well, really your batteries, but you have to run your intended volume of water you want to move against your, well, 'volume of power' you get from the batteries.

    And then, just for kicks, you get choked brought back to reality with budget - whaddya got for to bring to the party?
    Last edited by bdt; 28-03-2012 at 11:20 PM. Reason: gah, typo!

  4. #4
    Super Grandmaster BCO's Avatar
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    You will definitely be able to use a solar pump. I have experience lifting water up to 100m at 600l/hr with solar. It's not cheap tho.

  5. #5
    Grandmaster agentrfr's Avatar
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    Quote Originally Posted by T-Man View Post
    Hi
    I need to lift water 3m. Will a solar pump work? The volume is about 50 liters/day.

    First, what size (w) pump will I need? Secondly, will I be able to do it with solar?

    I have seen solar powered fishpond pumps but I don't think they will be able to provide the 'lift'.
    You can't calculate directly the wattage you need for a pump to do that, for a bunch of complicated reasons, but in laymans terms it comes down to how the motor is geared to the pump, like the transmision in your car. Faster water has lower pressure. You need to look at the pump curves for each pump that satisfies your requierments.

    50L/day = 5.787E-4 L/second

    So your pump equation P = -kV^2
    P = -k(5.787E-4)^2 + 3m,H2O

    So k = just under 9x10^6 seconds^2/meter^5, (9 million). You should be able to take that to a pump expert, and he could sort you out. Or just look at a combined pump curve and select one that has the flowrate at that head.

    For the wattage, we can make an educated guess, 50L/day at 3 meters. Ep = mgh = 50*9.81*3 (assuming you are pumping pureish water, SG = 1) = 1471,5 J/day = 17.03mW just for pumping. Efficiency is terrible for small pumps, most energy going to heat. So the pump, if built properly will be maybe something like 2W.

    So you are looking for a 2 Watt pump with a k value of around 9 million.

    So yeah, a solar pannel can do it easily. But you need to find one with a pumpcurve for what you are looking for (the pump has to be "geared" right to pump high head with low flowrate).
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  6. #6
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    Quote Originally Posted by agentrfr View Post
    You can't calculate directly the wattage you need for a pump to do that, for a bunch of complicated reasons, but in laymans terms it comes down to how the motor is geared to the pump, like the transmision in your car. Faster water has lower pressure. You need to look at the pump curves for each pump that satisfies your requierments.

    50L/day = 5.787E-4 L/second

    So your pump equation P = -kV^2
    P = -k(5.787E-4)^2 + 3m,H2O

    So k = just under 9x10^6 seconds^2/meter^5, (9 million). You should be able to take that to a pump expert, and he could sort you out. Or just look at a combined pump curve and select one that has the flowrate at that head.

    For the wattage, we can make an educated guess, 50L/day at 3 meters. Ep = mgh = 50*9.81*3 (assuming you are pumping pureish water, SG = 1) = 1471,5 J/day = 17.03mW just for pumping. Efficiency is terrible for small pumps, most energy going to heat. So the pump, if built properly will be maybe something like 2W.

    So you are looking for a 2 Watt pump with a k value of around 9 million.

    So yeah, a solar pannel can do it easily. But you need to find one with a pumpcurve for what you are looking for (the pump has to be "geared" right to pump high head with low flowrate).
    you forgot to add the momentum component.

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