Need smart electrician to help!

Hi Patrick.
I don't consider myself a smart electrician. A smart electrician might advise you to consult with a state licensed electrical contractor instead of giving away free and possibly incorrect information over an internet forum but, if you cannot find such a contractor who has first hand experience with these types of RE inverters nothing has been gained so, I'd like to take a crack at it. I'll also give you links to the information I have found. As for telling you how to wire it all up, I will have to refrain from that because I cannot actually see for myself what you have. If I am right though, it should be fairly straight forward wiring.

You say there is a "neutral" wire coming from the pump motor? Is this what you see in the controll box?
http://www.do-it-yourself-pumps.com/franklin-electric-submersible-pump-control-boxes.htm
The explanation provided at the above site is somewhat confusing. It makes a reference to using a neutral wire with the incoming power but it tells us to land it with the EGC or grounding wire. This is pointless. The only time a neutral is needed is to obtain one or more single 120 volt line(s) from a 120/240 supply. The neutral provides a safe potential and can "carry back" the unbalanced load of multiwire branched circuits. When 240 volt alone is needed a single grounding wire is sufficient because the load is balanced against the two "hot legs" for the potential.
Are you sure its not a yellow "L2" wire? Anyway, it sounds as though it may be a simple capacitor start single phase 230 vac motor, only I would guess that the capacitor(s) is in the control box you mentioned. As opposed to being in or on the motor itself. What you are wanting to know is how to supply 3 wire, 230 vac to the controll box from a single inverter. Correct?
There is a single inverter capable of suppling 4 wire, 120/240 vac. Its the Magnum Energy MS-AE series inverter/charger.

 !!CAUTION!! !!CAUTION!! !!CAUTION!! !!CAUTION!!
The wire coming from the pump motor that you are calling a "neutral" wire, may not be a neutral wire at all. Be sure you fully understand whats going on with this before appling power to the control box. Does the control box have a terminal for a neutral wire with the in coming power supply? Is there a neutral wire with the existing supply wires? If so, where is it landed?
 Here is some more information about the subject from someone who has been in the business of RE water pumping a long time. http://www.wholesalesolar.com/Information-SolarFolder/Invt-sizingforwellpump.html
Heres is the Magnum MS-AE inverter/charger (24 vdc model)
http://www.wholesalesolar.com/products.folder/inverter-folder/magnum_ms_4024AE.html

Just out of curiosity, would changing the pump be out of the question?

Hmm well you're probably right, I just assumed what the wires were.  Here's the diagram of what's in my control box:

http://www.do-it-yourself-pumps.com/franklin-electric-submersible-pump-control-boxes.htm

Changing the pump is not totally out of the question, but the well pump guy that installed my current pump told me a 115v pump would not be able to provide enough power to pull water up.  My pump is 120 feet down.  He also told me that even if it was capable of doing it, it's not recommended because there would be a huge loss of efficiency and reduced pump life.  ... Is that true?

Hi Patrick,

Thomas is very likely correct that the pump has a capacitor start motor.  That would be the best explanation for more than two wires. 

I have a 3/4 Hp pump and a much shallower well.  I'm running mine at 230 volts.  The line losses start to add up at 115 volts.  I measure 6 Amps running with a 20 Amp surge at startup.  I have it battery backed up with a pair of Xantrex DR1524 inverters.  I use the two inverters stacked to get the 230 volts.  It was a bit of a toss-up as a 1500 va transformer to go from 115 to 230 would cost almost as much as the second inverter.   

The Magnum inverter looks like it will probably do what you want, but at a steep cost.

If you're very serious about powering your pump only from solar, I'd suggest using a DC pump.  In doing so, you remove one layer of inefficiency in the inverter. 

AltE sells a Shurflo, and there are several other brands out there.  Not super cheap, but still less costly than the Magnum. 

Good luck,

Tom T.

"I have a 230v 10amp well pump.  It's a franklin electric 3/4hp pump.  It has a control box in my basement.

There's FOUR (4) wires coming out of the pump.  2 "hots", 1 neutral and 1 ground. "


Your pump has 2 "hots", a ground and the last wire runs from the start capacitor in your control box to the pump start circuit....it is NOT a neutral....your pump is a 220-240v ONLY pump, know commonly as a "3 wire" pump ( they don't count the green, ground wire ). A "2 wire" pump ( actually 3 with the ground ) has the start capacitor on the pump itself rather than in the control box on the surface somewhere, and could be either a 120v or a 240v pump.

The advantage of a 3 wire pump is that if the start capacitor goes out, you can replace it by simply changing the capacitor in the control box ( most people just buy a new control box ) instead of having to pull the pump out of the well to change it ( or the capacitor on the pump ).

My understanding of the PSX-240 Outback transformer is it will do exactly what you want far cheaper than going to a DC pump or stacking another inverter since you already have the setup you do dedicated JUST to the well pump.  You would have to ask if the Outback will work with any brand inverter, but I suspect it will.