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  • help required with solar system

    Hi Everybody, I have bought 2 solar panels to run my swimming pool but I am totally confused on where I go from here. If possible I dont want batteries as the pool will only run in daylight hours. A friend told me i only need a voltage controller and an inverter?? I want to keep costs of the system down to a minimum. I enclose a picture of the label on the rear of the panel, the pool pump takes approx 5 amps. Please can anyone advise me from here? I am a retired electronics technician (aircraft) but i know little about solar installation....many thanks Jim IMG_1922.jpg

  • #2
    Hi Jim, what's the operating voltage of the pump?

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    • #3
      hi , thanks for your response, the pump is using 240 volts mains voltage

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      • #4
        How many hours a day does the pump need to run, and does it need to run all year, or just part of the year?
        On average, those panels would only give you around 2 KWh per day, which wouldn't run that pump very long since it's a 1200W pump that needs 1.2 KWh every hour.

        Typically you multiply the power consumption (watts) with the number of hours per day (hours) to arrive at the energy used per day (watts x hours, AKA watt hours or Wh), and then work from there to get solar array size and battery size:

        https://www.solarpaneltalk.com/forum...battery-design

        I won't go into the battery requirement because I don't know if DC pumps are available that could do when you want, but here in the U.S. it would typically be done with batteries that would cost a fortune and make the energy cost significantly higher than mains power.

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        • #5
          It always seemed to me, CA could solve their energy problems if there was a
          good panel driven pool pump. Bruce Roe

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          • #6
            Hi sdold, the pump needs to run for about 5 hours per day and only during daylight hours. the label on the pump says 5amp but a power of 0.75kw. sorry to be so thick but i dont quite understand your reply? does this mean that I can get a constant 2kwh from the panels when the sun is shining? If I only run the pump when there is sufficient power from the panels do i still need batteries? If so what other equipment would I need? If I fitted a dc pump would that make life easier? Thanks again, so sorry for not understanding your reply

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            • #7
              Something's not right, or I'm missing something. 240V x 5A = 1200W, not 750W.

              Two 260W panels is 520W under lab test conditions, you'll probably see around 450W peak and over the course of an average day you'll probably harvest about 2000 watt hours, give or take. You didn't answer my question about the time of year, so I'll assume all year long. In the summer you might get around 3 KWh per day, in the winter maybe 1500 Wh. That's not nearly enough to run the pump unfortunately. Even assuming only 750W for the pump, that's nearly 4 KWh.

              If I only run the pump when there is sufficient power from the panels do i still need batteries?
              The panels can't provide sufficient power to run the pump, the total panel wattage is less than the pump requires.

              Can you power the pump from the "mains"? Even if it means trenching, burying conduit, etc. it would probably be your best and cheapest choice.

              Last edited by sdold; 10-22-2018, 05:31 PM.

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              • #8
                Originally posted by Jim in France View Post
                Hi sdold, the pump needs to run for about 5 hours per day and only during daylight hours. the label on the pump says 5amp but a power of 0.75kw. sorry to be so thick but i dont quite understand your reply? does this mean that I can get a constant 2kwh from the panels when the sun is shining? If I only run the pump when there is sufficient power from the panels do i still need batteries? If so what other equipment would I need? If I fitted a dc pump would that make life easier? Thanks again, so sorry for not understanding your reply
                For starters the most your panels will produce in terms of power will never be more than the STC rating of 260 W/panel = 520 W as per the nameplate information, and that will happen only rarely, if ever. Most all of the time the panel output will be less, like ~ 80-85 % of that STC output maybe 4 hrs./day in sunny weather and probably less than that ~ 80-85 % most hours of the year depending on panel orientation. With a battery system and ~ 520 STC W of PV, depending on your solar climate - if sunny - you might get something like 700 kWh/yr. or less out of it as a SWAG.

                Maybe you're like most others who think stand alone PV is a simple plug/play, but you'll probably be quickly disabused of that notion once you figure out what you'll need in terms of batteries and other items required for a stand alone PV powered motor for a pump, and that you'll be into some serious money and maint. to accomplish that duty. Nice hobby/learning experience, but I'd not do it with the idea of saving any toil or treasure.

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                • #9
                  Pump motors also have a "Power Factor" (PF) that is likely about 0.7 Power factor is a sort of loss caused by motor windings, and causes motors to consume more power then they would first appear to. So that 1,200w might actually need a 2,000w supply/inverter. Getting a pic of the pump motor nameplate would be nice.

                  Often, spending more money on a multi-speed pump, then useing it on a low speed, results in the same flow rate, but less power consumed. But you have to read the pump curves for the gear.
                  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

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