newbie question on voltage

CHEVYGUYCHEVYGUY Registered Users Posts: 6
I am looking at putting in a grundfos solar pump. The pump requires at least 30vdc. I am looking at different panels. Setup A. is 3 panels at 60 watts 48v each. Setup B is 3 panels 60 watts 12v each. If I do each setup in series A will be 180 watts 144v, B will be 180 watts 36v. Would it make a difference which one I use? Thanks


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: newbie question on voltage

    Higher Voltage = less current for the same Watts. Less line loss through the wires. The higher Voltage set-up would probably be more efficient, providing the Voltage doesn't exceed the pump's maximum (figures for which I can't find just now).
  • QuabillionQuabillion Registered Users Posts: 22
    Re: newbie question on voltage

    As an owner of an grundfoss SQ-Flex maybe I can help.

    The DC range is 30v to 300v, with built in MPPT for solar OR wind.

    I use a higher voltage / lower amperage setup to feed the pump due to it being about a 200 foot wire run. This allowed me to use "regular" well pump cable (10AWG 3 conductor) instead of having to use larger wire $$$$.
  • BB.BB. Super Moderators, Administrators Posts: 30,716 admin
    Re: newbie question on voltage

    I would go with the higher voltage unless you find something very specific in the specifications (like efficiency falls to 50% at high voltage)...

    These pumps also work with 120-240 VAC. The following is from this PDF booklet:
    The motor has three internal limitations:
    •maximum power input (P1) of 1400 W
    •maximum current of 8.4 A
    •maximum speed of 3600 min-1.
    The pump delivers its maximum performance when one
    of the above limitations is reached.
    Supply voltage
    Flexible as regards power supply and power range, the
    motor can be supplied with either DC or AC voltage:
    •30-300 VDC, PE
    •1 x 90-240 V – 10 %/+ 6 %, 50/60 Hz, PE.
    1,400 watts / 8.4 amps = 167 vdc minimum for maximum power
    30 vdc * 8.4 amps = 252 watts at minimum voltage

    So, depending on how much power you are expecting from the pump, and if you are going to use a genset at backup power... I don't see why not run this thing at "maximum" voltage to keep copper costs down.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenPowerManiacGreenPowerManiac Solar Expert Posts: 453 ✭✭✭
    Re: newbie question on voltage

    I agree with what's said. Also, sets up a possibility of expanding the system easily.
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