Grundfos 6 SQF-2 question

Desert Rat
Desert Rat Solar Expert Posts: 147 ✭✭✭
in Solar Water Pumping #1
I'm involved in a well project for a village in rural Mexico. They already have a new 6 SQF-2 pump. We will be powering the pump directly from solar panels. The specs from Grundfos show a maximum current of 8.4A for the pump motor. I called NAWS with some questions, and the guy I spoke with said that 8.4A was the minimum current for the motor; that the motor would not start at a lesser amperage. This doesn't sound right to me. Thoughts?
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
    Any motor will require a higher current to start from stall, think of pushing a car, takes more energy to get it moving, less to keep it moving, the Grundfos website has a sizing tool where you enter water requirements, location, hours of sun, total head etcetera to determine  PV required.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #3
    It's the maximum, but don't concern yourself with what goes to the motor (vs the controller).

    You want  panels producing 30-300 VDC, with 120-300V being best.  100W is the lowest they list, 2000W is the max (but it will only use up to 1400W).  See pump curves here:

    https://www.solar-electric.com/lib/wind-sun/SQFlex_Product_Guide.pdf

    I am available for custom hardware/firmware development

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  • Desert Rat
    Desert Rat Solar Expert Posts: 147 ✭✭✭
    #4
    So is it OK for the solar array to produce more than 8.4A?
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #5
    Think of this as it is like your household electricity use, you plug in a vacuum that uses 9 Amps and there is 120V and ~15 amps waiting at the plug in...  only the amps needed are used...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
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  • Desert Rat
    Desert Rat Solar Expert Posts: 147 ✭✭✭
    #6
    Thanks to all for your help.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #7
    Desert Rat said:
    So is it OK for the solar array to produce more than 8.4A?
    The larger the array capacity, the longer the run capabilities, reaching operating current sooner and ending later in the day.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    edited February 2018 #8
    At 120V, the controller will make use of up to ~11.7A.   At 300V, it won't use more than ~4.7A.   In all cases, excessive amps or watts capability in the panels is OK.

    I am available for custom hardware/firmware development

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