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Author Topic: Solar back up for 220v well pump?  (Read 4055 times)

ReluctantWarrior

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Solar back up for 220v well pump?
« on: January 11, 2010, 05:17:34 PM »
Just had a well installed but the company DIDN'T HAVE ANYTHING but a 220v pump.  I'd really like to do a solar backup for the pump but I'm finding it challenging to adapt to 220v without a generator.  I know I'm probably in for a call to the electrician, but was wondering if any of you have attempted this.

Thanks!

Ash
http://www.1moreday.org

Offline “Mark”

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Re: Solar back up for 220v well pump?
« Reply #1 on: January 11, 2010, 05:20:17 PM »
Due to the power requirements of a 220 volt pump, you'll save a lot of money going with a generator. You could do it solar, but you'll spend a lot of money on a capable inverter.

If you can, pump into a holding tank with the 220, and get a second, lower powered pump you can run off solar to supply your house.
The government is great at breaking your leg, handing you a crutch, and saying “You see, without me you couldn’t walk.” — Harry Browne

Offline millwright

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Re: Solar back up for 220v well pump?
« Reply #2 on: January 13, 2010, 09:12:46 PM »
I have recently seen something on solar pumps (submersible). The details have fallen out of my head, but I know they are out there.
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Offline No Prob Rob

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Re: Solar back up for 220v well pump?
« Reply #3 on: January 17, 2010, 10:17:12 PM »
Here is a link that may help

http://www.solarpumps.com/products.html

Keep in mind you will also need an above ground tank because of the low flow rates, and electric pump system to supply pressure to the house. However in a grid down situation you could easily access the water from the tank.

I have investigated and for a turnkey system for our home it will run $7-8 K. Not cheap but if there is no electricity you will only last 3 days without water.
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SouthernLiving

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Re: Solar back up for 220v well pump?
« Reply #4 on: January 20, 2010, 07:15:40 AM »
You can use a 120V inverter and a single phase 1:2 transformer rated appropriately for the load.  Used 480V to 240V control transformers can be found at online salvage dealers.  These are generally made to go in motor control centers.  You'll have two wires on on the primary side and two wires on the secondary side. 

The 110V hot and neutral from the inverter will be connected to the secondary (usually labelled X1 and X2).  It does not matter which wire goes where.

When you power this up the remaining two wires (usually labelled H1 and H2) will have 240V across them.  Connect these to the pump leads, make sure you are still running through the pressure switch and any other controls.

If you are using a modified sine wave inverter the transformer is going to convert the higher frequencies on the edges of the waveform into heat.  This cuts down efficiency significantly.  Make sure you have good ventillation.  A pure sine wave will have close to 100% efficiency through the transformer.

ReluctantWarrior

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Re: Solar back up for 220v well pump?
« Reply #5 on: February 01, 2010, 08:02:27 PM »
Thanks, SL!  Great info.  Here's some more good stuff from the kind folks at ARFCOM.

http://www.ar15.com/forums/topic.html?b=10&f=17&t=631836

SouthernLiving

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Re: Solar back up for 220v well pump?
« Reply #6 on: February 05, 2010, 05:07:36 PM »
RL,
The step up transformers shown on AR15 will work, but you don't need anything fancy for just a well pump. 

What you have is most likely 1/2 HP, so say it pulls about 400W at full load.  A .5 kVA (500W) transformer will do.  The motor will pull more current at startup but only for a very short period of time.  Transformers are rated for the amount of power they can pass without excessive temperature rise - very short moderate spikes of current at startup will not destroy the transformer.  Just make sure the enclosure is well ventilated.



I probably have a couple dozen of these laying around our shop.  If you actually do get a PV system installed I'll give you one.  You pay shipping.  Weight is about 10 pounds.




ReluctantWarrior

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Re: Solar back up for 220v well pump?
« Reply #7 on: February 07, 2010, 09:35:34 AM »
Wow, thanks, SL.  I'll let you know when we're at that point.  Would it be helpful for you to know the actual draw (with startup spike) of the pump?

SouthernLiving

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Re: Solar back up for 220v well pump?
« Reply #8 on: February 07, 2010, 01:22:51 PM »
Just the HP.  Everything else is figured from their.

Offline Dave

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Re: Solar back up for 220v well pump?
« Reply #9 on: February 07, 2010, 01:54:10 PM »
This inverter from Magnum will run 220V without having to stack inverters. If you shop around they can be found for just under $2000, which is still alot. However, if you get a good inverter it will be just over $1000 anyway. By the time you put together the parts for another solution to running water, you'll add up to near $2K anyway.

It is an expensive solution, but at least this avoids having to piggyback inverters.

http://www.altestore.com/store/Inverters/Off-Grid-Inverter/3000-to-5500-Watts/Magnum-MS-AE-4448-Inverter-Charger/p5839/