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  • Solar system for well pump... Parameters are include!

    Ooops, make that included... Hello, everbody! New guy from Florida... I did some searching and have an idea of what I want the solar system to do and the parameters that it would need to work in, but I need help on the solar end. Here are the details:

    [B]Well Pump Motor[/B]
    1HP motor - .75kw
    115/230 v. (Currently wired for 230 but could rewire for 115 so I could utilize the inverter for other purposes)
    19.2/9.6 amp
    I calculated a 2208 watt draw


    [B]Well Pump[/B]
    Gallons per Minute (GPM) = 10GPM
    Desired GPM usage a day = 5 minutes pump run time or 50 gallons a day

    [B]Solar Panel I Already Purchased[/B]
    145w polycrystalline
    Vmp 18.7v
    Imp 7.75A
    Voc 22.3v
    Isc 8.37A

    [B]I still need:[/B]
    Charge controller - I'm thinking MPPT 30amp if I expand: [U]What do you recommend?[/U]
    Batteries - [U]Which ones and how many do you recommend that are at a reasonable cost?[/U]
    Inverter - I'm thinking 2000/4000 watt, and do I need a pure sine to run a well pump, what do you recommend?

    [COLOR="#FF0000"][B]What charge controller and batteries would I need if I doubled my GPH output to 10 minutes a day or 100 gallons of water?[/B][/COLOR]
    Sincere thanks for your time and recommendations in advance. I don't want to throw a system together and hope it works, but plan a system to work within set parameters.
    John

  • #2
    Originally posted by Psychguy1 View Post
    [B]Well Pump Motor[/B]
    1HP motor - .75kw
    115/230 v. (Currently wired for 230 but could rewire for 115 so I could utilize the inverter for other purposes)
    19.2/9.6 amp
    I calculated a 2208 watt draw


    [B]Well Pump[/B]
    Gallons per Minute (GPM) = 10GPM
    Desired GPM usage a day = 5 minutes pump run time or 50 gallons a day
    Well John you are not going to like any of my answers. Problem is running motors off of Solar battery with conventional motors is very expensive.

    First your calculations is all wrong 2208 is a mystery number I have no idea how you came up with. A 750 watt motor ran 5 minutes per day uses 750 watts x .09 hours = 67.5 Watt Hours. In Florida all you would need on paper is a 20 watt panel, 2 amp charge controller, 12 volt @ 30 AH battery, and a [U][B]4000 watt inverter[/B][/U].

    But here is the problem, it would never work. As soon as the motor tries to start your inverter will immediately trip off line from low voltage. Reason is Flooded Lead Acid Batteries can only deliver about a C/8 discharge current before the voltage at the terminals drop and crash.

    If you have ever look at car batteries you will see a spec called CCA which means Cold Cranking Amps. It tells you how many amps a 100% fully charged battery can deliver for 30 seconds at a voltage of 7.1 volts. Did you catch that @ 7.1 volts on a 12 volt battery? Batteries have internal resistance and what the CCA rating is internal resistance specification of [12.6 volts - 7.1 volts ] / CCA. So if CCA = 500 amps the resistance is .011 Ohms.

    Even though on paper you only need a 30 AH battery, a 30 AH battery can only deliver about 3 to 4 amps. Beyond that and the voltage will fall off to below 10 volts. Your inverter trips off at 11 volts. You rmotor will draw around 3500 watts at start up and at 12 volts that is 290 amps. So to run a 4 Kw inverter @ 12 volts you need a 2320 AH battery or about a 1800 pound battery that cost around $3000.

    However that is not the end of your problems. a 20 watt panel cannot support a 12 volt 2320 AH battery. It will take at least 1500 to 2000 watt solar panel and 2 very expensive 80 amp MPPT charge controllers.

    OK you need to go back to the drawing board and come up with another solution like using a 12 or 24 volt DC motor that runs .1 to .4 GPM to refill your 50 gallons if you are going to do this with solar. But be aware it will still be very expensive and never ever pay for itself. I mean geez 67 watt hours os less than 1 penny worth of electricity. If you spend more than $100 it will take over 10,000 days or 30 years to pay for itself. Well not really because you will replace the battery every few years and the battery will be half the initial cost. Ole fashion wind mill comes to mind.
    MSEE, PE

    Comment


    • #3
      Since all you need is 50 gallons a day I would look at replacing the pump with something like a Shurflow 9300 pump that is designed to operate solar direct. Along with this you would also want a Linear current booster, Solar panel and about a 500 gallon cistern.

      Now how it would work is that the pump will run as long as there is enough sun into the cistern. A float switch can shut it off if the cistern is full. Use your 50 gallons daily as need with 9 days held in reserve for if the sun doesn't shine tomorrow.

      No batteries are needed as the cistern replaces them. Panel would be sized according to how deep the pump is set in the well.

      The pump will need to be rebuilt about every 5 years but is way cheaper than the required battery bank would be.

      Here are several examples of setting it up that way:

      http://www.builditsolar.com/Projects...terpumping.htm

      And I think this is one of the better DIY examples:

      http://www.otherpower.com/otherpower_waterpumping.html


      WWW

      Comment


      • #4
        WWW thanks for chipping in. I knew there are solar pumps out there but no experience with them.
        MSEE, PE

        Comment


        • #5
          Dereck and WWW, thank you for your replies. It appears that the solution is not easy. I did read on about the direct-solar-powered-pumps, but it looks like the pump is submersible. My problem is I have a 2" well casing and a 2 stage deep well pump. The well is 100' deep and the Shurflo 9300 looks like it would require a 4" casing. I'm gonna email one of the Surflo pump distributors to see if they have any solutions. I already have a 5KW generator, but I would like to have a "Plan B" in place. I greatly appreciate you guys taking the time to try to help me... Thank You!

          John

          Comment


          • #6
            So, there are some tricks you can use to make it more likely to succeed.

            1) downsize the pump & motor, to 1/2 hp, or even 1/3 hp. You would increase run time, but decrease
            the horrific start-up surge. Still would have roughly the same total watts consumed per gallon. The
            hard part is, looking up the pump curves to select the right pump and motor. It may be that 1/3 is too
            small for 100' lift anyway. I know 1/2 hp can do 160' @8 gpm because I've been doing it for the last 3 years.


            2) stick with the current pump, and build up a 24 or 48V battery bank and suitable inverter that can manage the starting surge of the 1hp pump. Assume at least 5x the running amps, for starting. Calculate that back into the batteries and cables.
            pump wired for 240VAC, 9.6a is 2304 watts running * 5 = 11,520watts to start.
            from a 48V battery, is 240 surge amps, 48a running.
            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


            • #7
              Originally posted by Psychguy1 View Post
              Dereck and WWW, thank you for your replies. It appears that the solution is not easy. I did read on about the direct-solar-powered-pumps, but it looks like the pump is submersible. My problem is I have a 2" well casing and a 2 stage deep well pump. The well is 100' deep and the Shurflo 9300 looks like it would require a 4" casing. I'm gonna email one of the Surflo pump distributors to see if they have any solutions. I already have a 5KW generator, but I would like to have a "Plan B" in place. I greatly appreciate you guys taking the time to try to help me... Thank You!

              John
              I have seen setups on small diameter wells that used this type of pump. Not sure if that is the actual one though. It works similiar to the old windmill pumps just uses a DC motor to move the pump rod instead of a windmill. They also used a Linear current booster direct from solar and a cistern for storage.

              Downside is the down hole part of the pump needs to be pulled yearly to service the seals.

              WWW

              Comment


              • #8
                Mike, that is a great idea about looking into an alternative motor size. I will inquire if a 1/2HP motor will be able to run the pump. My brother-inlaw the engineer always said, "There is always a better way," and I think you found the solution that won't bust the bank!

                John

                Comment


                • #9
                  Downside is, you have to pull the pump.

                  When any size pump is wired up, the higher voltage option, uses less amps. The watts (power) stays the same, but you do need to account for the 100' of power cable down the pump hole, when you figure your line losses. I have very long runs to my pump station, and then another 100' of the submarine cable down to the 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


                  • #10
                    led signs

                    wow thats a great info..... i never heard of it...

                    Comment


                    • #11
                      Originally posted by vendraline View Post
                      wow thats a great info..... i never heard of it...
                      Completely useless.
                      MSEE, PE

                      Comment


                      • #12
                        Originally posted by Wy_White_Wolf View Post
                        I have seen setups on small diameter wells that used this type of pump. Not sure if that is the actual one though. It works similiar to the old windmill pumps just uses a DC motor to move the pump rod instead of a windmill. They also used a Linear current booster direct from solar and a cistern for storage.

                        Downside is the down hole part of the pump needs to be pulled yearly to service the seals.

                        WWW
                        Although the solar pump (lift pump) mentioned can be used sharing a 4" well casing with an existing pump, there is no way that its 1 5/8" pipe can fit in the same 2" casing as the pipe and electric of the present pump. If the OP wants to go toward that pump, he will have to remove the old pump completely. Submersible pumps for 2" well casings are pretty rare these days, so that does also limit the options of going in with an AC or DC submersible which would be more solar friendly.

                        I have not seen any real complaints about the Simple Pump on the Internet yet. It is pricey, but offers something most other pumps cannot. And if you lose the solar system or the motor burns out, you can just switch to using the manual handle and still get water from the well! Try that with a submersible.
                        SunnyBoy 3000 US, 18 BP Solar 175B panels.

                        Comment

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