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Best Inverter for deep well pump

I never even considered that a pair of beefy looking MPP inverters creating a combined of 4,800 watts could falter in the face of surge current even if it's less than 4,800 watts. This is valuable information to consider when growing my solar power system, thank you all.

Size of Pump MotorRunning WattageStarting Wattage
1/3 HP750 to 8001,500 to 2,400
1/2 HP900 to 1,0501,800 to 3,150
3/4 HP1,500 to 1,8003,000 to 5,400
1 HP2,000 to 2,4004,000 to 7,200
1.5 HP2,500 to 2,8005,000 to 8,400
2 HP3,750 to 4,0007,500 to 12,000
3 HP5,000 to 5,50010,000 to 16,500
5 HP7,500 to 8,00015,000 to 24,000
7.5 HP10,000 to 11,00020,000 to 33,000
10 HP15,000 to 16,00030,000 to 48,000
 
Last edited:
offgriddle said:
I never even considered that a pair of beefy lookig MPP inverters creating a combined of 4,800 watts could falter in the face of surge current even if it's less than 4,800 watts. This is valuable information to consider when growing my solar power system, thank you all.

Size of Pump MotorRunning WattageStarting Wattage
1/3 HP750 to 8001,500 to 2,400
1/2 HP900 to 1,0501,800 to 3,150
3/4 HP1,500 to 1,8003,000 to 5,400
1 HP2,000 to 2,4004,000 to 7,200
1.5 HP2,500 to 2,8005,000 to 8,400
2 HP3,750 to 4,0007,500 to 12,000
3 HP5,000 to 5,50010,000 to 16,500
5 HP7,500 to 8,00015,000 to 24,000
7.5 HP10,000 to 11,00020,000 to 33,000
10 HP15,000 to 16,00030,000 to 48,000
Click to expand...
Good chart but it may be a little optimistic. My well pump runs at 2000W but start surges to 9000W. Actual measured.
 
offgriddle said:
I never even considered that a pair of beefy looking MPP inverters creating a combined of 4,800 watts could falter in the face of surge current even if it's less than 4,800 watts. This is valuable information to consider when growing my solar power system, thank you all.

Size of Pump MotorRunning WattageStarting Wattage
1/3 HP750 to 8001,500 to 2,400
1/2 HP900 to 1,0501,800 to 3,150
3/4 HP1,500 to 1,8003,000 to 5,400
1 HP2,000 to 2,4004,000 to 7,200
1.5 HP2,500 to 2,8005,000 to 8,400
2 HP3,750 to 4,0007,500 to 12,000
3 HP5,000 to 5,50010,000 to 16,500
5 HP7,500 to 8,00015,000 to 24,000
7.5 HP10,000 to 11,00020,000 to 33,000
10 HP15,000 to 16,00030,000 to 48,000
Click to expand...
This is why having numbers in hand BEFORE you start buying things is so important. BTW, I would say your chart above is overly optimistic. I have a 1hp pump, and it's MEASURED starting surge is 38A X 240V =9120AV. After getting my numbers, I was on the phone with each company's engineers to talk to them about what their units could power.

It's likely that four of your Mpp inverters couldn't start my pump. This is why the low-frequency inverters cost so much more. Because they are actually designed for serious off-grid loads, not just your TV.
 
MichaelK said:
This is why having numbers in hand BEFORE you start buying things is so important. BTW, I would say your chart above is overly optimistic. I have a 1hp pump, and it's MEASURED starting surge is 38A X 240V =9120AV. After getting my numbers, I was on the phone with each company's engineers to talk to them about what their units could power.

It's likely that four of your Mpp inverters couldn't start my pump. This is why the low-frequency inverters cost so much more. Because they are actually designed for serious off-grid loads, not just your TV.
Click to expand...
HOLY TOLEDO, i didn't even know that low frequency and high frequency inverters existed, once again my hats off to you Michael for sharing this information and everyone else that takes the time to share what they know and of course ultimately Will for hosting this forum.

Thank You Thank You Thank You
www.yiyen.com

Which is better? A “low frequency” & “high frequency” inverter? - YIY | Yiyen Electric

Power inverter has two types: Low frequency and High-frequency power inverter. off-grid inverter is simple which convert the DC power stored within a battery (direct current, 12V, 24V or 48V) into AC power (alternating current, 230-240V) that can be used to run your household items and...
www.yiyen.com
 
Why is it that magnum inverters are never mentioned in threads like this? (not being facetious). I use a magnum and have had no problems to date (4448 pae) but I am always looking to learn.
 
11+ years running a 240VAC 1/2hp, 4" well pump, 160lift off of a XW6048 inverter
It's a native split phase 240VAC inverter, 6kw cont rated, easily handles the motor starting surge
(as must the battery internal resistance, cables and interconnects)
 
mike95490 said:
11+ years running a 240VAC 1/2hp, 4" well pump, 160lift off of a XW6048 inverter
It's a native split phase 240VAC inverter, 6kw cont rated, easily handles the motor starting surge
(as must the battery internal resistance, cables and interconnects)
Click to expand...
those are pretty solid from what I have seen, as are the outback and magnums. any low frequency inverter is going to handle the strain better than a high frequency. the other thing to consider is that a modified sine wave low frequency inverter is cheaper than a Sine wave low frequency and might do the job as well, but this is something that you should consult with the pump makers engineers (not sales reps) as to if they would be happy with modified sine wave.
 
Running a motor ( the larger, the worse) from a mod sine inverter will greatly shorten the lifetime of the motor. The harmonics generate about 20% more power loss (HEAT) in the motor windings, and that extra heat comes from the PV & batteries.
 
mike95490 said:
Running a motor ( the larger, the worse) from a mod sine inverter will greatly shorten the lifetime of the motor. The harmonics generate about 20% more power loss (HEAT) in the motor windings, and that extra heat comes from the PV & batteries.
Click to expand...
there ya go figured someone might have better knowledge about that. I run all my stuff off of my magnums which are all sine wave so I have no issues, but i originally chose the sine wave versions so that I could be guaranteed to run any and all electronics without fear. as the motors came later I never even bothered to study up on that bit as my inverter power was as clean (if not cleaner in some cases) than what came out of the wall.
 
mvonw said:
Looking for advice (preferably from someone who has actually done this) used an inverter to power my cabin. My primary draw is a 240 volt 1hp well pump @ 500 feet depth. I have been running it for years with a 6500 watt Honda generator, but even with that the generator pulls pretty hard when the pump kicks in. I would guess I need an inverter that would handle 4000 watt surges, at least.
Is one 48 volt 240 volt inverter better, or two 120 volt inverters ganged together better/more advantageous?
Click to expand...
You'll need an 8 kw inverter. Not that the pump uses that much when running but the surge on a 1hp pump is massive to start it up especially @ 500 ft & you'll need a low frequency inverter. They have some head room to put out usually double the rating briefly whereas a high frequency inverter will not deliver much past it's rating. I know this 'cuz I have a 120v 1/2 hp shallow 70 ft well & it sometimes shuts down my low frequency 4kw inverter on occasions.
 
MichaelK said:
I've been running my well pump solely off of solar for three years now, and I'm very pleased with the results. I have a 1hp Grunfos 240VAC pump, that's similar to yours. I would disagree with the 24V suggestions given above. Using a clamp meter on the control box, I found the my wellpump draws about 10amps while running, but 37-38amps right at startup. This was measured with a Fluke meter with the ability to measure "inrush current". That's 9000+ watts at startup. I install a 48V Schneider XW+6848 to power my pump, and it has performed flawlessly the last three years. My panels are on rotating mounts, so I can face them eastward in the morning, then turn west in the afternoon. With my panels, I can keep the pump running with no battery depletion from about 8:30am till 4:30pm. If sticking with 24V is important, one alternative that might work is a Dual-Conext SW4024s wired in parallel. It's also a 120/240VAC inverter, but when two are linked in parallel, they will match phases and double output.


View attachment 9404
Click to expand...
Michael what batteries and solar panels are you using?
 
As long as you're talking about expensive, serious low-frequency inverters to run a well pump, consider SMA Sunny Island.
European model is 220V, US is 120V so you need either a transformer or two of them.
You can connect 3 for 3-phase (good idea for running motors), or four for more wattage single phase.
Each one produces 5750W continuous, 11kW surge for 3 seconds.

At $5000 each (msrp) they aren't cheap. But you can probably find new in the box liquidation units around $2000.

Discover the Sunny Island 4548-US / 6048-US! | SMA America

The efficient island manager Sunny Island 4548-US / 6048-US ► Now with 20 % more power! ► Efficient, simple, flexible and durable! ► Check out now!
www.sma-america.com www.sma-america.com
 
First off, I have 0 experience with wells this deep, I have little hands on experience with wells in general and the 1 one well I observed a guy struggling with was an old girlfriends dads from almost 30 years ago.

He was having issues with pumps failing in his 200ish foot deep well. He was hell bent on having a big pump that could supply shower after shower in a house with 4 girls, him and his wife.

His well didnt have adequate recovery rate to supply what he was trying to do and he was a moron and was getting poor advise.

After the first failure I had suggested installing a very small volume pump down the hole to fill a large atmospheric holding tank on the surface, then use a simple low pressure pump to supply the 45+ psi to the house. After several thousand dollars worth of service calls trying to make a 1 pump system work this is what was done. I broke up with his daughter a few months later but it did work without incident while I was around.

2 pumps has several advantages:
  • A low volume down hole pump reduces ground water depression and is better for the well itself as it will draw in a lot less sediment and debris.
  • Not adding the service pressure to the head pressure greatly reduces strain on the down hole pump and pipe.
  • Even at 0.25gal/min you will get 360 gallons in 24 hours making even a low producing well viable.
Just some food for thought
 
I am going to use a Grunfos SQF6-3 my well pump needs to be @ 700’
I have a slow yield well .
At first I was going to run it off solar panels but now I’m thinking about running it from my out back 36/48 inverter .
The guys tell me it can run off a 2200watt Honda so it should work good off the out back
I’m thinking of running it 10 min on 1 hour off three times a day so 30 min @ 6 gallons min 180 gallons a day .
I use a holding tank and 120v RV pump to feed the house .
This seams like a better option then running I bid inverter .
Most of the time I’m using 2/300watts of power from the inverter .
 
I'm in a very similar boat , building a trailer mounted system ( enclosed car hauler ) to power " just the well " and when I'm visiting the cabin it will also supplement power to my RV which has its own system. I am looking for a 48 volt inverter , split phase low frq that can handle the start up. but my well is at 850 ft ( that's right the pump is at 850ft the hole is 1250 ft deep ) I do not use a pressure tank , so start up against high head pressure is not there . It pumps to a 1000 gallon holding tank ,that's it. Another system runs a pressure pump to the house. I think its a 2 hp pump ?
But I need to find a 6kw or 8 kw inverter , here's why i say 6 or 8 kw. I can run it off my Honda 6500 EU , and we are at 8000 foot above sea level so the generator is de-rated about 20% But I have seen ( in not all ) of these split phase inverter use 2 inverter inside , one for each leg. So I believe its either MPP or grow watt , but basically their split phase inverter has ( on a 6 kw ) two 3000 watt inverters , like i said one for each leg. so you can under size yourself thinking the total power is what you have available . SO I am open to suggestions.
I need a good split phase inverter or a big single phase that i can run through a transformer . Also would like a all in one type ( inverter / charger / charge controller )
 
chadjones99 said:
I'm in a very similar boat , building a trailer mounted system ( enclosed car hauler ) to power " just the well " and when I'm visiting the cabin it will also supplement power to my RV which has its own system. I am looking for a 48 volt inverter , split phase low frq that can handle the start up. but my well is at 850 ft ( that's right the pump is at 850ft the hole is 1250 ft deep ) I do not use a pressure tank , so start up against high head pressure is not there . It pumps to a 1000 gallon holding tank ,that's it. Another system runs a pressure pump to the house. I think its a 2 hp pump ?
Click to expand...
What I would highly recommend you do is the same thing that I did when I was in the design-phase of my off-grid system. I bought this clamp meter that has an "inrush current" feature. It will measure the peak current that occurs in the first fraction of a second right at startup. It proved to be very valuable, because a standard AC clamp meter is not fast enough to "catch' the inrush (I tried).
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With this inrush meter you'll get hard data on what your pump is drawing, and then you will KNOW the design specifications you need to meet.
The Schneider XW Pro can surge to ~12,000W
The Outback Radian can surge to ~14,000W

If you need more surge power than that, two or more of these units can be paralleled together to increase the total startup power required. Once you know what power level you need to meet, then you will be able to design it to work on the first go around.
 
Steve_S said:
Well, if your pondering replacing the pump, then dive right in, get a Grundfos SoftStart SQ series and never worry about it again. They have 120V & 240V with various capacities. They are NOT cheap but they are the cat's meow.

Submersible Well Pumps

Grundfos submersible well pumps are available in a wide range of sizes and materials to fit your application needs.
ca.grundfos.com ca.grundfos.com
Click to expand...
Absolutely love my Grunfos SQ well pump..magic!!
 
The pump is 850 ft in the ground so not replacing it, I can say that I can start it fine with a honda EU 6500 generator.
Im not at the property to run a surge ( amp ) test on it. As Im out of town working.
Was looking to order something soon as prices are going up on everything. I do have an inverter question. on a split-phase pass-through inverter. how can I word this. .... what happens if the input side of the inverter is being powered by a single-phase generator? meaning L1 & L2 on the input outlet are the same phase like you see at a RV park that only has 30 amp plug and you use one of those 30 to 50 adaptors?
 
I would really, really try to dissaude you from making a quick purchase before you have real data on hand. That may turn out to be a mistake that will cost you dearly. Maybe one piece of advice I could give you is if you HAVE to buy it now, buy an inverter designed to be paralleled with a second unit. That way, if you find out it is under powered, you can add a second inverter side by side later.

Some inverter ACin terminals can be jumpered to provide the same phase to both L1 and L2. I believe that Will P. mentioned this on some past post. Read the owners manual concerning that before you buy. Most owner's manuals can be downloaded for their manufacturer's website.
 
good advice, The 2 main uses for the inverter will be to power my RV ( which has its own system ) but as a backup means, Ill be staying in the Colorado mountains long term off-grid, lots of solar I just gotta finish putting it all up. The 2nd use for the inverter will be to power a deep well pump once a week for about an hour. And the output on L1 and L2 will be from the inverter only ( from the battery ) but when powering my RV If I have to use the generator to top off battery, etc its a single phase 30 amp generator. so input L1 & L2 will be the same phase. Ive just never tried that before . was wondering how a split-phase inverter would react to seeing an input on both lines of the same phase.
And like I said I'm not there to test well pump amp draw. butI do know a 5kw generator will run it.
thanks for info
Chad
 
Here is a pump chart originally posted by another member Mike94945. He's an electrical engineer, specializing in solar installations, so I trust what he posts religiously. I'd use that as part of your info during the design phase. His chart data matches my real-world measurements of my own pump to a fraction of an amp.
1648606282820.png
 
chadjones99 said:
Wow thanks , that should help
Click to expand...
An additional question I'm looking at a split-phase grow watt 8kw inverter . what happens if you only supply power to L1 ? I want to use it in an off-grid set up from battery and solar, but I do have a single-phase generator ( 120 volt) So I will feed power on the input of the inverter to L1 , does this just pass through L1 ( update I just called signature solar & they said yes it will pass through 120 on L1 and charge battery ) but. they were unable to answer what I thought would be a basic question ( even though they tried & were helpful ) . I even downloaded the manual & spec sheet. What is the start-up inrush/surge output capacity of this inverter in AMPs I.E. 70 amp for 10 Ms , etc . This is what will tell me if it will handle my well .( which looks like it has a start-up surge of 70 ) , Also if I tie the L1 & L2 on the output of my generator ( it only has L1 ) together on the input of the inverter does it pass through 120 / 120 on L1 / L2 output side of the inverter or does the built-in transformer split-phase it ? or does it catch fire LOL ?
This is a :

Growatt 8kW Split Phase Off-Grid Inverter | SPF 8000T DVM-MPV​

Thanks for the help
 
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