# How to power my 1/2 hp 220V well pump from an inverter



## jimigunne

I am setting up a solar power system, its 12V. Currently have 300W of panels, will add more soon. I will buy a battery bank of go cart batteries soon. I have a large 120 to 220 V power transformer. I need to be able to run a 1/2 hp 220 V submersible pump from this system in case of power failure. I need a little help in sizing the inverter, and as to whether a modified sine wave type is OK or not. 1/2 hp would be about 800watts ( but the peak when it starts is much higher, I know. this would be about 3.6 amps at 220 V. This would be about 7.2 amps of input to the transformer at 120V. Any recommendation on a good inverter for this. I have to power two fridges that will use 3 amps, a few fans, and some lights also. This submersible pump uses a franklin capacitive starter box. I have read in Amazon reviews that some inverters that SHOULD seemingly be able to power a 1/2 HP submersible pump, having adequate power rating, were unable to run it nonetheless. Maybe that capacitor starter does not like anything but pure sine wave?


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## MattB4

They do make a 220vAC inverter that is spec'ed for well pumps but it is not inexpensive. You want to be cautious about inverters that are sold as 220v that are not US standard since Europe and Australia use 220v versus our 120 volt. This means only one 220v powered wire and a neutral not two 120v powered leads as we have. 

You might look into simply buying a 12 volt Well pump.


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## wy_white_wolf

That 7.2 amps at 120 is 72 amps at 12vdc Plus losses. You really need to look at a 24 or 48VDC system instead of the 12v. You will also have a lot more choices for inverters with the higher voltage.

WWW


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## JeepHammer

jimigunne said:


> I am setting up a solar power system, its 12V. Currently have 300W of panels, will add more soon. I will buy a battery bank of go cart batteries soon. I have a large 120 to 220 V power transformer. I need to be able to run a 1/2 hp 220 V submersible pump from this system in case of power failure. I need a little help in sizing the inverter, and as to whether a modified sine wave type is OK or not. 1/2 hp would be about 800watts ( but the peak when it starts is much higher, I know. this would be about 3.6 amps at 220 V. This would be about 7.2 amps of input to the transformer at 120V. Any recommendation on a good inverter for this. I have to power two fridges that will use 3 amps, a few fans, and some lights also. This submersible pump uses a franklin capacitive starter box. I have read in Amazon reviews that some inverters that SHOULD seemingly be able to power a 1/2 HP submersible pump, having adequate power rating, were unable to run it nonetheless. Maybe that capacitor starter does not like anything but pure sine wave?


I have two well pumps, and I power the house/grounds from the solar array.

The best advise I can give you,
ECONOMY IN SCALE,
The LARGER the solar system, the cheaper it runs.

Your Figures,
3.6 Amps X 220 Volts = 792 Watts 'Run' current.

Does this include the 'Head' or 'Lift' the pump has to do from a deep well?
The pump can draw a LOT more current trying to push water up a pipe 200 or 400 feet from a deep well...

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Since you don't have an ammeter on the pump, you won't know what it takes to fire it up, sometimes it can be 4X the 'Run' amperage...

Your Figures,
7.2 Amps X 220 Volts = 1,584 Watts. On Startup.

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The Capacitor box will help smooth out the 'Modified' sine wave a little, but in most cases, the pump manufacturer tells you SPECIFICALLY to use a TRUE SIGN WAVE power source.

The 120 to 220 converter boxes are about useless, and they are HORRABLY INEFFICIENT, they will often consume up to 30% of the input wattage, reducing what you can get to the pump considerably.

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Your 'Best Bet' is to get an inverter that will output in 220 Volts AC, Pure Sine Wave.

A 2,000 Watt CONTINOUS output inverter isn't very much money and will make your life a whole lot more simple in the long run.


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## stanb999

Your best bet is a 12v well pump, small cistern and 12v pressure pump.
I have had a setup like this for 2 years and it's been flawless.

It uses a 200 watts kit (Renogy from amazon)
two 120 AmpHr deep cycle batteries from walmart
two food grade 55 gallon barrels for cistern. From a local guy (craigs list)
A deep well pump from shurflo
Shurflo pressure pump.

All it it was about 1100. Just can't be done cheaper. 


P.S.
Solar for the most part gives very little power @ 120 volts without a huge battery bank... Huge battery banks take lots of panels to properly change.
To pull 800 watts will mean 66 amps @ 12v. to pull that current for even a few mins continuous would require a battery bank of 3-4 120 amp hour batteries.


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## JeepHammer

Depending on well head (rise from pump to surface) a 12 volt pump might not be possible.
I can tell you the 12 & 24 volt DC pumps didn't last long for me.


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## TnAndy

jimigunne said:


> Maybe that capacitor starter does not like anything but pure sine wave?



That may be the case.

Outback, for example, makes a great pure sine wave inverter, and you can buy their FW-X240 transformer to give you up to 4,000w of 240vAC out of a 120v single inverter (though at 12v, you're looking at some hawking big wire between battery bank and inverter to get to 4kw)....so, yes, it can be done.

I don't know if the transformer you have will work with Outback FX series inverters or not. I've only seen the FW-X240 used in one instance.....my own system, for example, I stacked 2 FX inverters and generate 240vAC out all the time and didn't go the transformer route. I did it more to double my wattage output than for the 240v feature (our water source is gravity fed spring)

Also, as several have already suggested, go 24 or 48v. Personally, I picked 24v, and if I'd had any idea at the time what my system would eventually grow to, I'd have gone 48v from the start.


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## stanb999

JeepHammer said:


> Depending on well head (rise from pump to surface) a 12 volt pump might not be possible.
> I can tell you the 12 & 24 volt DC pumps didn't last long for me.


Your information isn't up to date... solar can pump from 1500 ft+

As far as reliability... you get what you pay for. Did you by a marine 12v pressure pump or the much cheaper rv ones?


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## Ross

How much water do you anticipate needing for emergencies? And for what? Might be easier/cheaper to store water than try to pump water off a solar set up and for long term you can't beat a generator. Plumbing in a tank to the cold water side that you can lock off and drain for use will keep (whatever size) available for emergencies.


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## MichaelK!

In my personal experience, 300 watts is not going to work. You can draw out all kinds of specifications based on what the manuals say, but when you actually flip the ON switch, you'll get low-voltage switch-off.

What I've found personally when running my electrical motors off-grid, the batteries just aren't enough to start the motors, irregardless of what they will tell you they can do. What I've found in the real-world is if I want to run something that needs 500 watts, there'd better be 500+ watts coming immediately off the panels to get the motor started.

What does that mean? Try to power up a large circular saw at noon on a sunny day...no problem. Try to start the same saw after sunset the same day...inverter shutdown.

This is the kind of inverter you want to power your wellpump.https://www.emarineinc.com/Magnum-MS4448PAE-4400W-48V-Pure-Sine-Wave-120-240V-Inverter-Charger-60A Couple this inverter with a bank of 8 L-16 batteries, and about 1500 watts minimum of solar panels, and I think you will have a workable system.


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## wy_white_wolf

MichaelK! said:


> ...
> 
> This is the kind of inverter you want to power your wellpump.https://www.emarineinc.com/Magnum-MS4448PAE-4400W-48V-Pure-Sine-Wave-120-240V-Inverter-Charger-60A Couple this inverter with a bank of 8 L-16 batteries, and about 1500 watts minimum of solar panels, and I think you will have a workable system.


Total cost of my solar setup on the well is less than the cost of this inverter. By the time you buy batteries and solar panels for this you'll be well over $5k and have to replace those batteries every few years.

http://www.homesteadingtoday.com/country-living-forums/alternative-energy/528021-we-got-water.html

If you want to do solar economically then you need to pattern your loads towards the use of solar. One could easily use a system similar to this to fill a cistern for the house. Then a second smaller to pressurize the house or gravity feed the house.

WWW


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## markt1

I have a 3/4hp Franklin box 2-wire deep well pump 140 feet down. My initial solar system was wired for 12 volts. I used an eBay 120v/240 volt transformer, a modified square wave Chinese inverter, and a Frankenstein-sized 3-pole double-throw switch, but only tried it once just to verify that it would work. It worked, pulling 140 amps at 11.5 VDC, running about ten minutes to fill my large water pressure tank. And a week later my well pump died. While the well pump was 18 years old, I am suspicious that the modified sine waveform damaged the motor windings and pushed it over the edge. The coincidence of the timing... So I got an Outback 24 volt pure sine wave inverter, re-wired my system for it, and have yet to try it out. I am a bit chicken since I don't have the $1800 to replace another pump. A 12 volt system will work for a 1/2HP pump, but go for an inverter with the pure sine waveform and expect to draw around 1100 watts to run it. However, You will have more inverter options if you opt to go with a 24 volt system. You'll need one that can handle a surge around 3000 watts for 1/4 second just to start the pump.


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## red-beard

The 1/2 horse power is the pump power. Look at the specs to see the actual draw. I suspect it is closer to 750 Watts on the draw.

As far as an inverter to power it, I am partial to Samlex inverters in the smaller lines. Make sure you're buying a UL approved/tested device.

For motor based system, you must use a Pure Sine Wave inverter. MSW (Modified Sine Wave) inverters are fine for heating circuits and electronics. But motors need a good sine wave. Motors will overheat with an MSW inverter. This applies to refrigerators and Air Conditioners

Electronics are OK with MSW, because the power supply converts the AC to DC before use.


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## alp770

jimigunne said:


> I am setting up a solar power system, its 12V. Currently have 300W of panels, will add more soon. I will buy a battery bank of go cart batteries soon. I have a large 120 to 220 V power transformer. I need to be able to run a 1/2 hp 220 V submersible pump from this system in case of power failure. I need a little help in sizing the inverter, and as to whether a modified sine wave type is OK or not. 1/2 hp would be about 800watts ( but the peak when it starts is much higher, I know. this would be about 3.6 amps at 220 V. This would be about 7.2 amps of input to the transformer at 120V. Any recommendation on a good inverter for this. I have to power two fridges that will use 3 amps, a few fans, and some lights also. This submersible pump uses a franklin capacitive starter box. I have read in Amazon reviews that some inverters that SHOULD seemingly be able to power a 1/2 HP submersible pump, having adequate power rating, were unable to run it nonetheless. Maybe that capacitor starter does not like anything but pure sine wave?





jimigunne said:


> I am setting up a solar power system, its 12V. Currently have 300W of panels, will add more soon. I will buy a battery bank of go cart batteries soon. I have a large 120 to 220 V power transformer. I need to be able to run a 1/2 hp 220 V submersible pump from this system in case of power failure. I need a little help in sizing the inverter, and as to whether a modified sine wave type is OK or not. 1/2 hp would be about 800watts ( but the peak when it starts is much higher, I know. this would be about 3.6 amps at 220 V. This would be about 7.2 amps of input to the transformer at 120V. Any recommendation on a good inverter for this. I have to power two fridges that will use 3 amps, a few fans, and some lights also. This submersible pump uses a franklin capacitive starter box. I have read in Amazon reviews that some inverters that SHOULD seemingly be able to power a 1/2 HP submersible pump, having adequate power rating, were unable to run it nonetheless. Maybe that capacitor starter does not like anything but pure sine wave?


Ok I hope I am of help here, I am a electronic technician and engineer. Ok, first be sure you use pure sine wave for maximum efficiency and so you don't burn anything up. One horsepower electric is 746 watts so if you have a half horsepower motor it would be half of that which would be 373 watts. It takes up to five times that on the start winding of the motor which is 1865 watts momentarily so you would need a 1500 watt pure sine wave inverter to run it, it probably would run it better at 2000 watts since you are transforming your energy through a step up transformer plus the current to invert the power. If you can charge you system at 24 volts and get a 24 volt inverter it will do much better and 300 watts way way too low to run it long. Most off gridders have at lest 750 watts to run their home, I have 1.25 kilowatt here and expanding to 1.8 in this next week. I hope this helps.


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## MichaelK!

Here's a pump table I harvested from another solar oriented forum. It's from a engineer named "Mike" living in the Sierra foothills. Looking at his table, I see that my 1.0hp Grunfos pump mirrors the table quite closely. This can be used for your planning purposes. To differenciate the types of pumps, 2-wire are self-contained while 3-wire have a pump starter box. Looking at the table, I can see that a 1hp 3-wire 230V pump needs 37 amps to start. I real-life, using a in-rush clamp meter, I've found my pump consuming 36-38amps at startup, just as the chart would suggest. Running amps for my pump is ~9.5A.

So, 21-22amps at 230V isn't too bad, just a bit more than half of my own pump.

Now you have a choice to make, do you want to go with rinky-dink toy solar, or do you want to go with serious whole-house solar? I chose the whole-house route, and I couldn't be happier! Now with my homestead having 120/240VAC, I've got a standard refrigerator, air-conditioning, and a 240V well-pump I can run from 8am till 4pm. Looking at the specs for the 1/2hp pump, you'd need about 1500W running, and 5500W startup. There are several quality tier-one brands you can chose from. Look at the Magum Energy MS4024PAE, Magum Energy MS4448PAE,
Schneider Conext SW4024-120/240, and the Outback GS4048-01 Radian. With about 3000W of panels on the same mounts that I've made, and you'll be able to run you pump for 8hr per day.

Sure, it's going to be pricey, but this is for a whole-house system that an electrical code inspector will sign off of.


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