Question on setting up DC submersible well pump

[DanaBlPl]

I recently purchased a Nemo DC Submersible pump for our remote well. The company said I could run the pump directly from the PV panel if I had an LVD in between. The well has a slow recharge rate so my plan was just to turn the pump on when the sun was shining full. We are in southern Colorado, with excellent sun. Based on their charts it looks like I'll be using #8 AWG wire and one 100w 12v panel. I'd love some suggestions on a simple switch for this purpose.

Thanks for your help.
Dana

[Mike90250]

The company said I could run the pump directly from the PV panel if I had an LVD in between.

That's a contradictory statement. Directly means PV panel ---- PUMP
If you install a LVD (whatever that is) you are not running the pump directly.

What I have heard of being done, is to use a PV panel wired to a LCB (linear current booster) to provide power to a motor, which helps prevent burning the motor out in poor sun conditions, and helps start the motor a bit sooner than straight solar connection.

[Audie Posadas]

Im not very familiar of DC to AC systems. I have a SP30-10/QF5010 190gpm@65mTdh 20Hp 230v, 3phase, 60hz. I would like to run this pump using solar panels. Kindly advice what is the best inverter and how many panels needed to run the pump.

[DanaBlPl]

LVD = Low Voltage Disconnect

It's this one: http://nemosolar.com/dcsubmersiblepumps/id45.html

I'm unsure how to wire it all together.

[solarix]

For "direct pumping" from solar you generally want a linear current booster (LCB) for keeping the pump going even when the panel voltage is low (like a MPPT controller for pumps).
A LVD (Low Voltage Disconnect) is for when you are running the pump off of batteries and don't want to over-discharge the battery.
Most pump manufactures will incorporate this stuff into their own Pump Controller which is usually mandatory to use if you want to keep the warranty.

DC or "solar" pumps are not very long-lived in my experience. To be able to run slow - they have to be "positive-displacement" (no slosh-back through the pump) - so needs seals of valves or tight clearances. All of which wear out (and quickly if the water has sediment in it). When the diaphragm fails, your motor gets wet and ruined - (ask me how I know).
Don't be cheap on solar pumps - they won't last long unless you do everything right.

[inetdog]

As long as your panels have sufficient wattage to power the pump at the output voltage of the panels, an LVD will serve to cut off power to the pump as soon as the cells are no longer able to deliver the required current and the voltage starts to collapse.

A Linear Current Booster (LCB) would do the same and if the pump is capable of running at less than full output when supplied with a lower voltage (a big IF for some pump designs) then the LCB would allow the pump to keep running for a longer time each day and deliver more water using the same set of panels.
The difference is that the LCB can convert a full voltage output at too little current to keep the pump happy to a lower voltage output at higher current (similar to what an MPPT input does on a CC or grid tie inverter.)

Those DC pumps (e.g. some Grundfos models) that can operate over a wide range of voltage and current and run well at partial output have an LCB function built into their controller boxes.

[DanaBlPl]

Since the well has a slow recharge rate, I believe it could quite often pump the whole casing out and need to be switched off to avoid damage to the motor, while the well recharges. Does anyone have a recommendation on a simple switch I could install the cut the power off to the pump? Seems like a lot of the ones I've looked at say AC only.

[Mike90250]

Franklin Electric has a Pump Protector, that can sense the pump being unloaded, and shuts it off. That's on my AC pump. I don't know if there is one for DC, check with the pump mfg, as to if they have something for your needs.

[ThomasWinfrey]

Is Franklin Electric good?

____________
FloTech Inc.

[Mike90250]

Is Franklin Electric good?

YES, they make excellent AC motors for well pumps. Usually a pump company buys the motors and pairs them up in their own housing, like in my .sig
Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) Good pump company, good motor company.