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DC-powered deep well pump

We have a 6" deep well - currently powered by 220V house power (that won't work with my 5KW genny - for reasons I cannot fathom).

After losing power again this weekend from the rain/ice storm - its time for an alternative.

So my question:

Would it be better to get an inverter and use the current AC powered pump - or change out the pump to a DC powered pump?

I have done a bunch of research on this and am not finding a definitive choice either way.

Appreciate any guidance.


Asked by Sean Cary
Posted Wed, 12/11/2013 - 14:17
Edited Thu, 12/12/2013 - 07:05


3 Answers

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The initial surge required to start a motor usually draws more power than the power rating of the motor in watts. That's why you need to size your generator for the starting surge rather than just the power rating of the motor.

I'm not sure what you mean when you ask, "Would it be better to get an inverter and use the current AC powered pump - or change out the pump to a DC powered pump?"

If there is no grid power, you can operate your pump with a generator powered by gasoline or propane. It's also possible to buy a large battery and an inverter to provide AC power.

It's usually more expensive to buy and maintain a battery + inverter system than it is to buy a generator. I have both at my house, so I know.

In theory, it's also possible to install a DC pump in your well, and to operate the pump directly from battery power. Several manufacturers used to sell low-voltage DC submersible pumps designed for off-grid installations. These DC submersible pumps acquired a bad reputation; they were unreliable. Almost all off-grid homeowner now use AC submersible pumps that are powered with a battery + inverter system or a gas-powered generator.

If your generator isn't powerful enough to operate your well pump, you have two choices. You can buy a more powerful generator, or you can swap your pump for a smaller model.

Most well pumps are oversized. My AC well pump is set at a depth of 200 feet, and it is rated at only 1/3 hp. It works fine. I am able to operate my well pump with my battery + inverter system, as well as with my 5-kW gas-powered Honda generator.

Answered by Martin Holladay, GBA Advisor
Posted Thu, 12/12/2013 - 06:59
Edited Thu, 12/12/2013 - 07:03.

Helpful? 0

Thanks, I am coming to the conclusion that whole house genny is in my future - living w/o water during extended power outages with two getting old!

Answered by Sean Cary
Posted Thu, 12/12/2013 - 10:26

Helpful? 0

I have quite a bit of experience using DC pumps from SunPumps. I use them to irrigate my farm using a drip irrigation system and a 3kw solar system. In any case, the controllers for these pumps are smart enough to eliminate the surge issue.

In any case, it's worth exploring.. They have solutions for many different setups.

Answered by Chris Barnes
Posted Thu, 12/12/2013 - 15:54

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