Water well battery bank replacement

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JRHill
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Water well battery bank replacement

Post by JRHill »

Last summer we lost water pressure and it scared me terribly. Fortunately it was just the bank. Checking it out, one of the 8 Trojan golf cart batteries has a bad cell. I had been expecting it since the well batteries were replaced Nov 2015. Not bad length of service but, even more than the house batteries, that bank never gets loaded more than 800 watts and the max charge to the batteries is slightly less. In fact, when the well pump is running and we have full sun it supplies the pump's load and even sends very little bit back to the batteries. So when the bank failed I disconnected the batteries and plugged the well pump into 120vac from the house. ...Been running like that since. The 4ea Phi 3.8-48 blocks in the house could care less about the well pump being off its own battery bank.

So I have 4ea 195w panels at the well on a mast doing nothing. They are the same model as on the house. During the winter our water usage is minimal so the well pump plugged into the house is nothing other than maybe a few extra amp/hours of generator time. I have a few options:
a) Move the 3 of the four well panels to the house roof. I have three open positions available that I never filled and I'll have a system spare. Just run the well permanently from 120v, or;
b) Buy another 48v PHI for the well and have it back to an independent system. Or;
c) Do nothing but cash in the old bank for the core value and sell the 45a Morningside controller.

A bank of batteries for 48v for the well is a complete overkill with a 800 watt load. I'm done with lead and will NOT buy a lead replacement bank. And in 15 years we've never been at a loss for water which was the original reason to have a separate system. And even if the house system was down I could simply run an extension cord to the well and run it off the generator to repressurize the well tanks (2 80g).

I have kicked around a 30ah PHI Helios (30ah) for $1300 but NAZ never has stock. If I almost doubled the battery cost I could throw a 3.8-48 in there for the well. But that's kind of a pricey protection for an event that's never happened. Lastly, the open 3 positions on the house roof are the most likely to be partially shaded which is why I never filled them. In the summer we don't need more solar generation. In the winter I could triple our total solar and still not make power with sunlight that isn't there. :???:

Option 'c' sounds better all the time. Any input?
fcwlp
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Re: Water well battery bank replacement

Post by fcwlp »

When I am doing an off-grid property my general recommendation is to run the well pump and possible booster pump off of the main solar system to avoid duplication of hardware and expense. In the Grundfos pump family this allows using a SQ series pump vs a SQFlex which also saves about $1,500. If the property has 60+ feet of elevation available, we will often put a storage tank up there and that provides plenty of pressure to feed the house. The other water storage option is a multi-thousand gallon pressure tank, fortunately our house came with, a 5,000 gallon pressure tank.
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Go with option c
raysun
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Re: Water well battery bank replacement

Post by raysun »

I'm all for consolidation. Running the well pump off the main, managing one battery - KISS.

How far is the well PV array from the combiner/FM80? Can a 10AWG line be run between the two in situ? If it's a long run, there will be losses, but the contribution would still be greater than Zero.

Another option would be to keep the Chinese charge controller attached to the well array and pipe its output to the battery bus. Jigger the settings so it's only charging during Bulk, and drops out prior to reaching termination. Again, the run might have line losses, but will contribute some.
JRHill
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Re: Water well battery bank replacement

Post by JRHill »

Thanks for the input, folks. Of course I like option C the most too.

As far as tying the well panels to the house system, I could get inside the house from the top of the mast with a little over 100' of wire in conduit. It would not be a fun trenching project at this point of our project. Have to tear through two large stone rock gardens, a buried propane line and a conduit taking power to and from the shop. Its another do nothing choice to me.
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