Well pumping in "standby mode"

[MichaelK]

First let me give you a little background. I'm developing a self-sufficient homestead in the foothills of the California Sierra. Our homestead land is on a south-facing ridge at about 5000 feet. Right now our cabin is powered by a meager 400 watt system charging Trojan T105s and powering a 1000 watt Xantrex inverter. It's OK for lights, TV, and occasional power tools. We have extensive garden space and about 110 orchard trees in the ground right now, that must be watered weekly. Our 400 foot deep well has a 1.5hp 240VAC Grunfos pump powered solely by generator power. The static water level of the well is at -100 feet, with the pump down at -380 feet.

We'll be retiring in the not distant future and I'm in the design phase for a more substantial system that can power the whole cabin and the well pump. I'm looking at this Renogy kit as the heart of the new system.
http://www.renogy-store.com/3600W-24...cabin3600p.htm  Renogy is local to my area, so it will be inexpensive to upgrade more panels at less than 1$/watt because I won't have to pay for shipping.

I'm debating whether or not I can successfully power the AC well pump on solar, or if I should keep using the generator. Let's assume I build the system with six 3-panel strings of Renogy's 300 Watt panels. I'd wire them such that each string of three produces 900 watts at 112.5 volts, going into Midnight's 200 controller. This will charge a bank of 8 L-16 Trojan batteries, wired in series for a 48V battery bank. Perhaps I'll utilize Magnum's 4400 watt 120/240V inverter.

Six strings of three panels is too many for the 200, so I'm thinking or orienting sets of panels in different directions to maximize production over time, but not go over amperage limits.  My idea is to position three strings of 3 panels facing due south, and another three strings facing southwest.  Assuming I'm getting a real 80% output, that's about 2100-2200watts from the south-facing panels at noon. The southwestern panels would be at a 45 degree angle to the sun, so maybe their output is about 400 watts.  Together, the six strings might be producing 2700-2800 watts.  That level of output should stay about the same as the sun swings over from east to west.

The starting amps of this pump is ~11.6 amps at 240VAC which works out to be 2785 watts. So, if the inverter actually puts out that much power at 240V, I could RUN the well pump without drawing down the batteries. The problem is the STARTING watts, which I understand, is much higher than other electric motors.  The well used to be powered by an ancient 4kw Onan, so I don't think the starting watts is much past 5000.

Studying the Magnum MS4448SPAE owner's manual, on page 31 they document running the inverter in "Standby Mode".  Here is the reference from the manual.

3.2 Standby Mode
The MS-PAE Series uses an automatic transfer relay and an internal battery charger when operating in Standby mode. Standby mode begins whenever AC power (utility or generator) is connected to the inverter’s AC input. Once the AC voltage and frequency of the incoming AC power is within the AC input limits, the automatic AC transfer relay is activated. This transfer relay passes the incoming AC power through the inverter to power the AC loads on the inverter’s output. This incoming power is also used to activate a powerful internal battery charger to keep the battery bank charged in case of a power failure. Refer to Figure 3-2 to see the flow of power from the AC input to the DC and AC output while in Standby mode.

Here's the link to the manual.  http://magnumenergy.com/wp-content/uploads/2015/04/64-0032-Rev-B-MS-PAE-Series_WebVersion.pdf

So, I start up my generator at noon, warm it up for 5 minutes, then switch on the well-pump.  I think that the surge wattage required (5-6kw?) would come from the generator, then, when pumping stabilizes, 100 % of the power could come from the panels.  After a minute, I could shut off the generator, and leave the pump running solely on panel/inverter output.

Is this a stratege that will work in the real world?  Has anyone here heard of that actually being done?  I'd much rather run my generator for a couple of minutes per day, rather than a couple of hours per day.  On the other hand, switching on and off that many watts might be really hard on either the inverter or the pump electronics.

[dgd]

I would use a Midnite Classic 150 and not the 200.
A Maximum Power Voltage (MPV) about 112v with 3 PVs probably means a 40 something no load voltage for each PV, so approaching the 150v working limit of the C150. But that would hardly matter as the C150 can handle up to 198v with a 48v battery bank. This HyperVOC range above 150volts will just not produce any power output from the Classic but since voltages in that range are only likely in cold very early morning you would likely get negligible power anyway even with a Classic 200.
Then as the sun starts to light up the panels they will heat and the power voltage will quickly drop to the MPV or more likely 70 to 80% of that.

The C150 with 48v bank should be ok with the 18 panels (4400 watts?) so just orientate them all south.

dgd

[MichaelK]

I would use a Midnite Classic 150 and not the 200.

The C150 with 48v bank should be ok with the 18 panels (4400 watts?) so just orientate them all south.

hello DGD.  Thanks for your response.  If you go over to the Renogy webpage I listed they are selling their "kit" with the Classic 200.  That's why I made that selection.  My real question though pertains more to the action of the inverter then the charge controller.  My single biggest concern is whether or not I can start/run my 240VAC well pump off the inverter?

Input from other sites suggests that the Magnum doesn't tolerate this.  A guy trying to run only a 1/2 hp well pump would trip his pump protector when the inverter relay tries to switch.  Another guy running his electric stove off of batteries/generator indicates that the Schneider ConextXW series can better handle high loads like this.  Considering how expensive the Schneider is though I may just want to skip the idea.

[mike90045]

My single biggest concern is whether or not I can start/run my 240VAC well pump off the inverter?

Input from other sites suggests that the Magnum doesn't tolerate this.  A guy trying to run only a 1/2 hp well pump would trip his pump protector when the inverter relay tries to switch. .....

The pump protector trips off when the internal transfer relay switches.  If you don't use a protector, you may be able to start the generator, start the pump, and shut off the generator, and let the inverter handle the running load.   But starting the generator for 6 minutes to start the pump, is hard on the generator.   The inverter may be able to handle the pump starting, it all depends on actual values it draws (pay an electrician $200 to use his $350 peak hold AC ampmeter) and if your battery & cables can handle the starting surge.

[CDN-VT]

Check with 1.5hp 240VAC Grunfos pump sellers for a smart start Grunfos  box . You might need to pull the pump & change  something . We did one two years ago with a 30' head @ 130' . really lightened the starting punch .
VT

Just another opinion