Grundfos 6 SQF-2 question

Desert RatDesert Rat Posts: 117Solar Expert ✭✭
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?

Comments

  • mcgivormcgivor Posts: 2,211Solar Expert ✭✭✭✭✭
    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 bank 

  • jonrjonr Posts: 1,077Solar Expert ✭✭✭✭
    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
  • Desert RatDesert Rat Posts: 117Solar Expert ✭✭
    So is it OK for the solar array to produce more than 8.4A?
  • westbranchwestbranch Posts: 5,090Solar Expert ✭✭✭✭
    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
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Desert RatDesert Rat Posts: 117Solar Expert ✭✭
    Thanks to all for your help.
  • mcgivormcgivor Posts: 2,211Solar Expert ✭✭✭✭✭
    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 bank 

  • jonrjonr Posts: 1,077Solar Expert ✭✭✭✭
    edited February 14 #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.
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