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  • Shallow Well Pump Setup

    I am wanting to do a simple system to pump water to house tanks....
    I have a 4.7m shallow well with 6" casing. My water level is 1.9M. I want to fill tanks 8m high with a total distance of 30m.
    I have 4500 liters in the tank to last 3 days. So worst case would need to pump 4500 maximum in one day but most days less than 1500. We are in North Brazil a couple of degrees from the equator. Very rare to have 3 days without usable sun....
    My placement of the panel is not ideal but I am thinking I will have at least 3 to 4 hours of usable sun. Plan to monitor current output and try to optimize location. Worst case was thinking of splitting panels to capture different angles... but rather keep it simple. So 4500 liters in 4 hours is the maximum demand but could live with 3000L.
    I am looking at suntech spmd3250HS or spmd4350HS. The first is 1.3 m3/h and second is 2.0 m3/h. The inverter is built in so the system is very simple. Solar panel and pump and of course some level switches.. The first might fall short of the maximum demand and the second might be 50% over. I can buy this for $600.
    Am I missing something.... any thoughts about which pump is better. The 1.3 is 3" diameter and 2.0 is 4" diameter. I do not know what flow the well will support... Advised it could be 6000LPH but that seems high.
    Thanks in advance for your comments.... just trying to make sure I don't have any surprises or misconceptions.

  • #2
    Sounds like a plan, if your skys are not especially cloudy. The smoke from forest fires
    lately I find costing more PV output than similar looking clouds.

    Near the equator your panels mount nearly flat? If you need more energy but have
    increased the panels to the limit (clipping?) of your system at noon, adding more
    panels splitting all between tilted east and west could considerably increase the
    number of peak hours running a day. The east strings are simply wired in parallel
    with the west strings. Here at 42 Lat this current curve was produce by arrays
    1 + 3, nearly the same peak as S array 2, but for 8 hours.

    This will have the additional benefit of considerably more output under clouds,
    which has been working well here for 8 years. Bruce Roe.

    PVm17Jn16.jpg
    Last edited by bcroe; 08-08-2021, 04:41 PM.

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    • #3
      Thanks for the information.... If I use the 4" pump the maximum input current is 12 amps. The 400 watt solar panel has an IMP of 10 amps.
      What happens when you parallel two panels together like you outlined. Do you not run the risk of twice the current? If you reduce the wattage of each panel would you risk not having enough current when there is no overlap of the panels.

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      • #4
        Originally posted by Obx_guy
        If I use the 4" pump the maximum input current is 12 amps. The 400 watt solar panel has an IMP of 10 amps.
        What happens when you parallel two panels together like you outlined. Do you not run the risk of twice the current? If you reduce the wattage of each panel would you risk not having enough current when there is no overlap of the panels.

        With your E and W panels in parallel, the MPPT controller does not care which
        supplies most current. By elevating the panels toward E or W, the peak noontime
        current is reduced as much as desired. In this plot a 61 degree tilt toward E or W
        gives a close to flat output all day, here the noontime sum (1 + 3) peak is actually
        a bit lower than a single alignment. You can fine tune that angle for your application.

        Energy available will also vary with season, I chose that axis alignment directly
        toward E or W, to optimize at Equinox, half way between min and max length
        days. That causes a bit of misalignment in peak summer, tending to equalize
        that more intense sun (less atmosphere and dust to penetrate). Winter is not
        great, but it never is, a lesser loss. At the equator I expect this effect will not
        be significant. But probably my 61 deg tilt toward E or W will need ADJUSTMENT
        for you.

        Understand MPPT driven PV equipment can adjust over a considerable range
        to make best use of the available energy. MPPT solar will adjust to use less
        than available current by allowing the panel voltage to go up, closer to Voc. The
        E-W arrangement elevation angle can actually be adjusted to have a LOWER
        peak current than a single alignment, while still delivering more total energy.

        One more point, your panels may be put on a 2 sided mount, costing less than
        a single alignment mount for the same number of panels. So all your equipment
        except the actual panels is more effectively used.

        The original purpose of this arrangement here, was to double the PV output
        under my so frequent clouds, always keeping the rest of the equipment busy.
        Of course pointing double panels at the noon sun would produce double
        current at that time, which would simply be clipped and unused since inverter
        capacity would be exceeded. The E-W arrangement fully uses the peak from
        each, at different times of day. It still works for the dispersed light under
        clouds, when alignment is less critical. This first 2 sided array was not best tilt.
        good luck, Bruce Roe

        NStrench.jpg

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