What are ways to reduce electrical consumption with a well?

[KimG]

I am building an off-grid home that will have solar battery power. We are going to have a well drilled, and believe we will get water at about 230 feet.... so maybe a pump will be placed at 200-250'...? I know that's a huge difference in the realm of well pumps. I'm trying to figure out the best techniques to reduce power use in our situation, and also to make decisions before drilling the well.

We need to be able to irrigate about 3 times a day during the high heat of summer for a food garden (we are in the desert SW). We have about 7500 gallons in total of rainwater catchment tanks which will be used for irrigation, but in our region of 6-15" of rain per year that's not enough even with our large roof area.

I'm trying to figure out ways to save on electrical use for when we have to irrigate with our well. Putting a tank in the air for gravity feed is not a feasible option for us at this time... but I will consider it if I can find a setup that is reasonably affordable. I wouldn't want that water coming into the house though, because I don't want all the water coming in our home to be warm/hot. It gets 118F here, and lukewarm "cold" water is really gross...been there done that already.

- So if we have to pump water from our well for irrigation at times, what are the best ways to keep the electricity use lower?

- Do I understand correctly from other posts that a CSV reduces amperage and therefore reduces electricity use? (I got that impression in this thread from the response on Jan 15, 2025: which plays nice with CSV - Goulds or Grundfos? )

- Will the casing size make a difference? Because the well is not yet drilled, I can still choose a casing size and type (within reason).

- Does anyone have pump brand recommendations?

Lastly, I wouldn't be into a noisy solution, either. Yeah, I know, a lot of "conditions" - but I have read enough to see there are a bunch of highly intelligent and clever thinkers here and I'm excited to see what you all come up with.

Thanks so much for all thoughts. I'm in process of designing our solar system, and this is why I'm trying to think ahead and figure how to lower our water pumping electrical usage. I realize that will depend on unknowns of the well drill and static water depth.

Kim

 

[Valveman]

An efficient pump is all you can do. There is no magic way to save energy. It takes X amount of KW to pump Y amount of water from Z a certain depth. It takes a lot of solar to do any irrigating. An elevated tank to store pressure doesn't save anything either. I would use a cistern storage tank, (maybe underground in your area) so the smallest well pump possible could be used. A booster pump in the cistern supplies pressure and water on demand. The Grundfos SQ pump plays nice with solar as it had a soft start built in. Adding a CSV would give you strong constant pressure and allow the use of a much smaller pressure tank. But with the CSV and a small tank you may need an extra battery that you can probably do without using a large enough pressure tank.

 

[Sponsor]

 

[Fitter30]

1lb of water pressure is 2.31'height
10 lbs is 23.1' height

 

[RetiredInGueydan]

I am building an off-grid home that will have solar battery power. We are going to have a well drilled, and believe we will get water at about 230 feet.... so maybe a pump will be placed at 200-250'...? I know that's a huge difference in the realm of well pumps. I'm trying to figure out the best techniques to reduce power use in our situation, and also to make decisions before drilling the well.

We need to be able to irrigate about 3 times a day during the high heat of summer for a food garden (we are in the desert SW). We have about 7500 gallons in total of rainwater catchment tanks which will be used for irrigation, but in our region of 6-15" of rain per year that's not enough even with our large roof area.

I'm trying to figure out ways to save on electrical use for when we have to irrigate with our well. Putting a tank in the air for gravity feed is not a feasible option for us at this time... but I will consider it if I can find a setup that is reasonably affordable. I wouldn't want that water coming into the house though, because I don't want all the water coming in our home to be warm/hot. It gets 118F here, and lukewarm "cold" water is really gross...been there done that already.

- So if we have to pump water from our well for irrigation at times, what are the best ways to keep the electricity use lower?

- Do I understand correctly from other posts that a CSV reduces amperage and therefore reduces electricity use? (I got that impression in this thread from the response on Jan 15, 2025: which plays nice with CSV - Goulds or Grundfos? )

- Will the casing size make a difference? Because the well is not yet drilled, I can still choose a casing size and type (within reason).

- Does anyone have pump brand recommendations?

Lastly, I wouldn't be into a noisy solution, either. Yeah, I know, a lot of "conditions" - but I have read enough to see there are a bunch of highly intelligent and clever thinkers here and I'm excited to see what you all come up with.

Thanks so much for all thoughts. I'm in process of designing our solar system, and this is why I'm trying to think ahead and figure how to lower our water pumping electrical usage. I realize that will depend on unknowns of the well drill and static water depth.

Kim

Before making all of these plans, I would have a viable water well drilled.

 

[KimG]

Thank you all for the info. The reason I was trying to get a better understanding ahead of drilling the well is that when you ask for pricing on a well, the company wants to bid a pump and system simultaneously. That gets nipped in the bud when you then say "an off grid well", because they can't sell the typical pump they would normally stock and bring with them to install. Then they start asking questions of what you are trying to do - and I didn't have enough understanding to say what I wanted. Thus far I've been getting bids that are solely for the drilling and capping aspect. Then I will hire a local company to put the pump in.

So I'm trying to get an understanding of what our options are and what we would like, etc. Thank you for all the input.

 

[Fitter30]

Have to first figure out pump depth, how far from well head to where the storage tank will be gpm any height difference above ground ( tank height). This is for figuring pump head.

 

[Valveman]

Like you said, very few pump guys have any experience with solar pumps. Plus, it will take a lot of solar to do any irrigating. I don't think you will catch enough rain to even consider. I would set up a two pump system using a booster pump in the 7500 gallon storage tank to supply 40/60 pressure water to the house. Then I would use as small a pump in the well as possible, and irrigate directly from the well at low pressure, as that will use less energy. Only pressurize the water needed for the house and have the well pump fill the cistern to 5,000 gallons or so. That way you can still catch 2500 gallons of rain if that ever happens.

Figure the flow rate needed for irrigation, determine the depth to the pumping water level, then you can size a well pump. I would recommend a very small well pump considering the batteries needed. Hanging on 1" poly at a reasonable depth it could be an easy DIY project. There is usually a lot more maintenance and replacements with solar pumps, and it could get expensive having a contractor come out as often as needed.

 

[KimG]

Thank you for the excellent detail above. Another question... Which motor type typically lasts longer - the helical or centrifugal? I see the Grundfos has both options.

Our current home (on grid) came with a Grundfos 120V pump which burnt out at just over 2 years old. I don't know why it failed, but their warranty is only 2 years, and so that wasn't confidence building for me! :-D

So now we have whatever brand of pump the well company stocked on this on-grid home, and I do want to put a CSV on this one. That's on the list.

Thanks for all the input above. You are all very generous with your information, and I so appreciate it.