System size for 220 volt well pump.

[Myakkadave]

Hi
I live in rural central Florida. I have a 5 inch well thats 485 feet deep. The submersible pump is 85 feet down in the casing. The well company didn’t give me much info about the pump. I see that the disconnect has a 30 amp breaker. What i’m wondering is how much amperage does a 1.5 hp pump use on start up? Wouldn’t my battery bank need to produce enough power for that? I know that once the pump is running it only uses about 8 amps. So the main question of course is how large would my system need to be to power this pump off grid?
Thanks

 

[400bird]

If you don't have a spec sheet for the pump, your options are to measure the start up surge or guess. A safe number is probably 5* running amps. So 40 amps? Might be better to measure

A good low 6-7kw frequency inverter should do the job as the should be able to surge to double their rating for plenty long enough to start the pump.

To figure out battery and PV size, you need to know how often the pump runs and do some math.

 

[RobertGreen]

Another consideration is that all pumps are Not created equal when it comes to starting surge.
Grundfos SQ pumps are often suggested on solar forums because they have a soft start built in (there's no startup surge). This would let you get by with a MUCH MUCH MUCH smaller inverter, even just a 120v version, so that you could use it for regular household stuff without requiring an additional transformer.

If your pump is only 85 ft down, why do you have a 1.5HP pump? Is it for a very high flowrate or is this just for a house?

 

[Myakkadave]

If you don't have a spec sheet for the pump, your options are to measure the start up surge or guess. A safe number is probably 5* running amps. So 40 amps? Might be better to measure

A good low 6-7kw frequency inverter should do the job as the should be able to surge to double their rating for plenty long enough to start the pump.

To figure out battery and PV size, you need to know how often the pump runs and do some math.

Thank you.
I have a kill-o-watt device for my house 120 items. Is there something like that for 220? Something that clamps on like a amp meter maybe? That would help determine the start up amps and run time over a 24 hour period.
Thank you for the help.

 

[Myakkadave]

Another consideration is that all pumps are Not created equal when it comes to starting surge.
Grundfos SQ pumps are often suggested on solar forums because they have a soft start built in (there's no startup surge). This would let you get by with a MUCH MUCH MUCH smaller inverter, even just a 120v version, so that you could use it for regular household stuff without requiring an additional transformer.

If your pump is only 85 ft down, why do you have a 1.5HP pump? Is it for a very high flowrate or is this just for a house?

I have a 10 acre property and use the well for house, barn, and pastures for animals. I thought about switching to a solar pump but this well is only about a year old so i figured i might wait until this pump fails.

 

[再生可能 エネルギー]

Thank you.
I have a kill-o-watt device for my house 120 items. Is there something like that for 220? Something that clamps on like a amp meter maybe? That would help determine the start up amps and run time over a 24 hour period.
Thank you for the help.

You need to get an Ammeter with in-ruch current memory.

 

[Myakkadave]

You need to get an Ammeter with in-ruch current memory.

Thanks
I have both a klein and a fluke ammeter. I’ll check to see if either has that function.

 

[Supervstech]

A 485ft deep well, with a 85' deep pump?

 

[RobertGreen]

A 485ft deep well, with a 85' deep pump?

That part got me, too. And a 1.5HP pump at that depth for that use case? For what it's worth, I've got a 1/2hp cheap amazon pump at 90' feeding a conventional 40-60psi pressure tank system and it pumps about 10 gallons a minute.
I'm also surprised by the idea of a 485ft well in rural central Florida. I'm not a hydrogeologist, but I kind of wonder if OP didn't get taken for a ride by the well driller.

 

[corndog]

Much of Florida has such a high water table that you can get away with the little above ground pump. You could go deep if you needed a huge draw down for ag purposes and had a slow recharge time, but really a 1.5hp isn't very big and probably could never draw down faster than 485ft can recharge. Maybe done for future upgrade, who knows. And I know there's not much elevation in Florida, but if the house were significantly higher in elevation, then you need more pump. Nice thing about 85ft is, you can set that thing by hand and pull it out by hand. Anyway, if wanting to go solar, you'll spend more in solar kit than you would buying a Grundfos SQ, so it's worth upgrading the pump and spending less in solar.

 

[MichaelK]

Here is a pump chart that another user, Mike92450, published a while ago. I find that my pump matches his table specifications down to tenths of an amp.

Looking at the chart, I see a 1.5hp pump requiring 45.9A to start. That's ~11,000W just at startup. Once it's running, the power required to run is ~2800W. If you really need to make sure, you need a clamp meter that has "inrush current" capability. I have this one, and recommend it.

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With my pump, I measured 37-38A at startup, and 9.5A running. A regular AC clamp meter won't work for inrush. It is not fast enough to catch the startup. I see that you say your pump draws ~8A, I would question the 1.5hp rating. Looking at the chart, 8A looks like it might be a 3/4hp pump. So, either the amperage or the horsepower rating might potentially be off?

I have a Schneider XW+6848, which starts my pump effortlessly. though my startup is just 9100W. It might handle 11kW OK, but I don't know from experience. But the paper spec say yes? Another quality inverter with just a bit more startup power is the Outback Radian, with a 14kW startup surge. A bit more $, but a bit more W.

My rule of thumb is to have twice as many watts of panels as your single largest load. Assuming your pump load is 2800W, then I would recommend 5600W of panels with a 600-800Ah lead-acid battery, or half that for Li (300-400Ah).

 

[Zil]

My samlex inverter manual has a chart "Inverter sizing factor". Third line down it has ' Well pump / Submersible pump' sizing factor times 3. "Multiply the Running Active Power Rating (Watts)" of the pump by this factor (3) " to arrive at the Continuous Power Rating of the inverter for powering " this pump.
The inverter needs be this Watts, the battery bank needs be sized to that inverter. If pump plate calls 2000W, the inverter needs 6000W. 6000W at 48 volts DC needs 125 DC amperes. At 24 volts DC, 250 DC amperes. Plus some for loss. At 12 volts DC, well don't do that. 500 amperes. This is just an example from Samlex Inverter. your pump has it's own data plate.

A note about well depth. A 400 plus foot deep well encounters an aquifer with pressure. The water will fill the column of the bore hole much closer to the surface. I can believe near 100 feet down from surface.

 

[onokai]

I have a 120 foot well and the pump is at 110 feet. Its a 3/4 hp motor (Franklin) its 240 v 30 amp as it is aways from house (about 130 feet)
It went in in 1998 and is still working great.The start up on this will draw the most amps and as I have 80 gallon pressure tank they are a bit less often. So for your factors as you do not know them you need a clip on amp gauge and find out the size of pressure tank and how far is the wire run?from there you will get a better idea of actual power needs