Grundfos 6 SQF-2 question

Desert Rat

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?

mcgivor

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.

jonr

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 Rat

So is it OK for the solar array to produce more than 8.4A?

westbranch

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...

Desert Rat

Thanks to all for your help.

mcgivor

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.

jonr

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.