solar panels for grundfos?

RegB Registered Users Posts: 1

I am new here and looking for guidance on a water pumping system. We are pumping water for livestock with a grundfos 6 sqf pump using a generator and a IO 101 box and a CU 200. With the generator the CU 200 reads 450 - 490 watts with 126 volts AC going to the pump. My question is what kind of solar system would run this pump? Does the voltage of the panels make a difference? Would four 145 watt - 18 volt panels wired in series do about the same thing that three 185 watt - 24 volt panels? I know the watts aren't exactly the same but what I am getting at is, does the panel voltage matter as long as you get the same ending voltage? The well is 160 feet deep, we have 12 gauge wire down the well, and it pumps to a storage tank about another 160 feet higher but it takes a mile of pipe to get there. What I am wondering is the 72 volts enough or do we need more? To get more do we use lower wattage panels and more of them or does it matter? I understand the math va=w but do we need more volts in this application? Also what panels are recommended?

Thanks for any advice,


  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: solar panels for grundfos?

    In theory, the SQF series will run on pretty low DC voltages (30 VDC up to 300 VDC), but you will run into other problems if it is too low. You need X watts to run the pump, and if you go with high amperage/low voltage on a 160 foot depth pump, you will need some pretty big wire. For over 100 foot run, we recommend you keep the total voltage output from the solar array in the 125 to 250 VDC range.
  • Fernweh
    Fernweh Registered Users Posts: 5
    Re: solar panels for grundfos?

    I have seen a many Grundfos SQF pump installation with 8x 80W solar panels.
    All the SQF pumps have the same motor installed.
    Please have a look at the attached Grundfos Service instructions which provides a ton of information about their systems.

    Sorry, the file is to large to be posted here. If you like, please contact me and I shall email this PDF file to you.