Grundfos SQFlex MPPT function

mxsolarmxsolar Registered Users Posts: 14
I am about to install a Grundfos SQFlex submersible pump and I have a couple of questions about selecting the right PV modules to run it.

The pump has an internal MPPT circuit and according to its spec sheet, its maximum input current is 7 amps.

My questions are:

Can I use PV modules with a high current like the Evergreen ES-A-200 (Imp=11 amps) without damaging the pump?

Will the MPPT circuit convert any excess current into usable voltage or will it just be wasted power?

I understand a MPPT charge controller converts excess voltage (from I-V curve Maximum Power Point) to current thus increasing energy available to charge batteries. However, I don't know if a MPPT circuit, like the one in this pump will bring down the current and maintain power via increasing voltage.

Can anyone comment on this?

Thanks.

BTW, the reason I am considering these modules is because I am able to get them at a very low price compared to others.

Comments

  • mike95490mike95490 Solar Expert Posts: 9,274 ✭✭✭✭✭
    Re: Grundfos SQFlex MPPT function

    I think the MPPT function works in down-converting a 70V array, to the motor voltage. Extra available amps from PV won't hurt, but you need to supply the minimum voltage the MPPT wants to see.
    Excess amps would be wasted, but then again, your 11A panels will nearly always have 7A avaib to the pump, even with slight haze, clouds or off angle sun. A 7A panel would starve the pump in the same conditions.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Dave AngeliniDave Angelini Solar Expert Posts: 5,910 ✭✭✭✭✭
    Re: Grundfos SQFlex MPPT function

    How deep and which model? It sounds like you are worried about the wrong parameters.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • mxsolarmxsolar Registered Users Posts: 14
    Re: Grundfos SQFlex MPPT function

    I have two wells but at this time I am installing only one pump, the other one will come later. The first well is 200 ft deep and the pump model is 11-SQF-2. I will be pumping about 7 GPM.

    The other well is only 70 ft deep, I am planning on using the same pump, and the water requirement is very similar.

    Thanks.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Grundfos SQFlex MPPT function

    DO you mean that those depths are the static levels or is that the depth to which you will lower the pump?
    What is the recovery rate of the wells?

    Eric
     
    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
  • mxsolarmxsolar Registered Users Posts: 14
    Re: Grundfos SQFlex MPPT function

    These are the levels at which the pump will be lowered. The well yields way more than I will be pumping.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Grundfos SQFlex MPPT function

    so then what is the vertical distance the pump has to lift the water?
    this allows evaluation of the pump vs delivery vs power demand.
    Why 7 GPM?

    NAWS shows:
    Model Type Max Head Max Flow PV Watts (Min-Max)
    3 SQF-2 Helical Rotor 360 Feet 3 GPM 100-340
    3 SQF-3 Helical Rotor 600 Feet 2 GPM 130-600
    6 SQF-2 Helical Rotor 360 Feet 6 GPM 100-650
    11 SQF-2 Helical Rotor 300 Feet 11 GPM 50-900

    looks like you will easily get the 7 gpm you need as it will deliver 11 gpm @ from 300 feet... maybe more pump than you need.

    What did Grundfos say about the power needed for your static level? their website is less than helpful..
    HTH

    Eric
     
    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
  • mxsolarmxsolar Registered Users Posts: 14
    Re: Grundfos SQFlex MPPT function

    Eric,

    I think I have the system sizing figured out. I think I have the right pump and I think I have calculated the PV wattage correctly.

    My question, though, is if I can use a module that puts out way more amps that the pump's specs say it can take (refer to my first post).

    Thanks!
  • mike95490mike95490 Solar Expert Posts: 9,274 ✭✭✭✭✭
    Re: Grundfos SQFlex MPPT function
    mxsolar wrote: »
    Eric,

    I think I have the system sizing figured out. I think I have the right pump and I think I have calculated the PV wattage correctly.

    My question, though, is if I can use a module that puts out way more amps that the pump's specs say it can take (refer to my first post).

    Thanks!

    It's ok, and the pump may run at a faster allowed speed, till it reaches it's max, as long as you stay under the Max Voltage Allowed.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Grundfos SQFlex MPPT function
    mxsolar wrote: »
    I think I have the system sizing figured out. I think I have the right pump and I think I have calculated the PV wattage correctly.

    My question, though, is if I can use a module that puts out way more amps that the pump's specs say it can take (refer to my first post).

    I had the 6-SQF-2 installed last fall and it's GREAT!! I find it simply amazing that you can put just about any voltage, AC or DC, to these things and they work.

    To answer your question, mine is powered by a Xantrex SW2512. Just because the inverter will output 2500W, the pump only draws what it needs/wants. Yours would be the same. The pump will draw what it needs just like any other electrical load, as Mike said.

    I also got the CU200 controller... all indications at a glance including watt draw, dry well and full tank. I had to engineer an easy relay addition since the Grundfos comes designed to shut off when a float signals that the 'livestock' tank is full. I needed it to shut off when my pressure bladder tank is full.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Grundfos SQFlex MPPT function
    mxsolar wrote: »
    Eric,

    I think I have the system sizing figured out. I think I have the right pump and I think I have calculated the PV wattage correctly.

    My question, though, is if I can use a module that puts out way more amps that the pump's specs say it can take (refer to my first post).

    Thanks!
    You can, but much better to use high voltage panels. The SQF will down convert high voltage, low amps to what the motor needs. It will not "up" convert high amps, low voltage - and you need a certain minimum voltage. Higher voltage also means small wire size needed.
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