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Run AC Submersible well pump for dripping irrigation

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  • Run AC Submersible well pump for dripping irrigation

    Hello guys,

    I'm new to the site and also new to all this solar panels world. A lot of things to learn.

    I have a small property with a well and I would like to use solar panels to get some irrigation going. The idea is just some dripping irrigation system so it wouldn't have to run very often. Here's what I would like to do.

    Install a submersible pump. I saw one in Amazon that is AC, 375 watts and 115 volts, it seems to be just what I'm looking for (I checked some DC pumps but didn't have very good reviews).
    I would like to run the pump every two hours (just during the day is ok) for 10 minutes (that should be more than enough to fill up the tank (200 gallons) and for it to empty.

    I would like to know where should I start.

    If my math isn't wrong (It probably is), to run the process 6 times a day I would need to generate 0.375 kw/hr every day @ 115v, which means that if I get 10 hours of light a day (the property is in Costa Rica so the minimum is close to 11 hours) I should be able to do it with (roughly) 4 100w x 12v panels?

    Now, I would need to store this energy between uses, is this doable with standard car batteries? how many would I need? which size?

    I will also need an inverter, what type should I get?

    For running the "program", would you recommend a timer or should I get some kind of sensor in the tank in order to decide when to start the pump? Is there something that I can use that will run the program when both things happen: the tank is empty (assuming a sensor there) and the batteries are full?

    I believe I would also need something that would prevent the batteries from overcharging, what would that be?

    What else am I missing?

    Thanks a lot for your info.

    - Will

  • #2
    First thing you have to do is determine how many watt hours you need in a day, and how deep your pockets are. Chances are once you find out how much it really cost, you will drop that idea like a hot potato. The only way to determine cost is how many Kwh do you need in a day. You cannot start until you do that.

    The best way to do what you want is to run a special DC pump directly from the solar panels to pump up water to a water storage tank above where you intend to irrigate. That way you use gravity to pump water to a low pressure drip irrigation system. To cover 1000/ft^2 with 1 inch of water requires 623 gallons of water.
    MSEE, PE


    • #3
      You are much better off pumping continously into a large tank while the sun is shining than trying to store energy in batteries to keep the pump running when the sun is not high in the sky or deliver high peak power to the pump.
      If you absolutely cannot put in a larger tank, and do not have access to grid power then yes, you will need batteries.
      SunnyBoy 3000 US, 18 BP Solar 175B panels.


      • #4
        Use a float switch in the tank. Use a tank larger than 200 gallons. Use a pure sinewave inverter when powering any motor. The motor for the pump has a half second starting surge current spec, your inverter has to be able to supply that without cooking, which means an expensive inverter
        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



        • #5
          Thanks a lot for the replies.

          Even though I wasn't thinking on that much water (the idea is just dripping for trees planted in the property) I've seen the costs of the parts and as you say, it is way more than what I was expecting. And since the property is in Costa Rica I would need to ship everything down here and that means an even larger cost (shipping and taxes).

          I think it isn't worth it right now, especially since I do have access to the grid.

          Thanks again!