Choosing pump to match existing panels

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  • feralgeometry
    Junior Member
    • Mar 2019
    • 5

    Choosing pump to match existing panels


    Hi everyone,

    Please note that I am a total newbie to solar and hydraulics, though I have some knowledge of electrical and electronic systems.

    I have a swimming pool that is partially filled with rainwater and I would like to pump the water out of it to an elevated tank for use to gravity feed a drip system. I can't leave the water in the pool and pump it directly from there as the pool will eventually be refilled and maintained.

    It so happens that I have been given 4 small panels each rated 15W, 17.5V and I was wondering if I could use them to power a DC pump to pump the water up during the day.
    I have a few months of time, so pumping only when the sun is up is totally fine.

    Does anyone have recommendations for pumps that will work straight away with the the panels ? Ideally something available in Europe.

    Thank you !
  • Mike90250
    Moderator
    • May 2009
    • 16020

    #2
    How high is the new storage tank going to be ? Hight = work, and more work means more power or time needed. 60w is not a lot of power. so it may take a long time.

    Figuring out the "head" needed, will drive the choice of pump.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment

    • feralgeometry
      Junior Member
      • Mar 2019
      • 5

      #3
      Thanks for your reply Mike.
      I think I need a total head of 4 meters (2m pool depth + 1m height of the water tank + 1m stack of pallets to keep it raised from the ground)

      Comment

      • J.P.M.
        Solar Fanatic
        • Aug 2013
        • 14939

        #4
        Originally posted by feralgeometry
        Thanks for your reply Mike.
        I think I need a total head of 4 meters (2m pool depth + 1m height of the water tank + 1m stack of pallets to keep it raised from the ground)
        Similar to what Mike writes, but I'd add: If you have grid power available, use that. Seems a lot of hassle for one application, especially when time may be a factor due to fouling of the water when the attendant problems of sight, smells and health considerations of open, standing water are take into account. After a few days you'll have a lot of green water. After 4 months, you'll have a swamp.

        To your pump choices: Figure out how long you want to take to drain the pool. Then, look at the pump curves for various submersible pumps that will pump the water out at ~ 4m head in the required time. Or pick a pump that fits your budget and read the discharge rate for that pump from its pump curve and est. drainage time from: drain time ~ = total vol. of H2O in the pool/pump discharge rate at 4m head.

        If you choose a D.C. pump/use the panels, look out for startup surges and check the power factor of the pump motor and take those into account when matching to your panel characteristics. Also, don't expect the panels to produce their rated power except under ideal conditions, and usually much less than their nameplate power rating.

        Unless you are completely off grid, I'd get a small A.C. pump that will deliver ~ 3-5 l/min. or so at 4 m of head, fit it with an accessible filter on the inlet, throw it in bottom of the pool ,and keep an eye on it. I've drained many a pool that way.

        Not a plug, and FWIW only because it has worked for me many times in very similar/identical applications to what you describe: I've had a Lil' Giant pump similar to their current 5-MSP for going on 50 yrs. I drained pools I've owned with it many times. Fit for purpose. It's A.C., draws maybe ~ 500 running W. or less, although I've never put a Kill-A-Watt meter on it. Current spec sheet/pump curve shows it pumps ~ 3,000l/hr. ~ 4m of head. That figure seems about right to my observations. Costs ~ $100 U.S. Plug & use. See Google.

        If you don't have/don't want to use grid power for this application, find a D.C submersible pump that will run on, say, 40W or so. but be careful of the starting current and power factor of the pump.

        Comment

        • Mike90250
          Moderator
          • May 2009
          • 16020

          #5
          So, now you look for a pump that will give you a flow of ___ at 4M head.
          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

          Comment

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