Converting existing well pump to solar

SystemSystem adminPosts: 2,511 admin
I am helping a non-profit that has a large pond that is pretty dry. The dam used to leak but that has been fixed but unfortunately, there has not been enough rain to fill it. They want to help fill the pond up and have a very nice sounding well that they could pump into the pond. However, they could not afford the electric bill to run this thing all day. Someone suggested that running it via solar panel might be a good idea and various folks are willing to chip in for the costs and I was tasked to try to figure all of this out.

Unfortunately, I am not sure yet what are the right questions to ask to begin nailing this down and am hoping you folks could help. The well currently has a typical 3/4 HP 220 V well pump. I am not yet sure how much the lift is, but am trying to get a handle on that. Once above ground, we would run it in a pipe downhill to the pond.

What else do we need to find out? The well used to provide all water to the place, so there is plenty of good water but they put in a better system a year or two ago and don't use it any more, although I am told it is in good working order. It seem to me that since they don't need the 220VAC pump it might be a better option in the end to replace the pump with a DC pump and do away with an inverter, but again I know nothing about these things. Another question I have, generally, is would a battery be a good, cost effective addition? Wouldn't 'need' one, I don't think, but the more hours per day, the faster the pond fills up.

What do I need to find out about the system to start being able to figure out a decent system.


  • CariboocootCariboocoot ✭✭ Banned Posts: 17,615 ✭✭
    Re: Converting existing well pump to solar

    Welcome to the forum.

    To be brief and blunt, solar is probably not the cheapest solution here.
    A 3/4 HP pump is probably submersible and that usually indicates significant depth to the water. There are direct-from-solar pumps that can do this job, but they're not cheap. Poke around NAWS solar/DC water pumps section and you'll see what I mean:

    Why is the utility power too expensive? Solar power tends to be far more so, especially if you have to change the pump out to use it. Will this be a long-term application or short-term? To just refill the pond may not be worth any significant investment, but if the water will continue to be needed/used it becomes more practical to spend some serious money.

    Until we know what sort of depth the water is coming from and what flow rate is required it's impossible to offer any solid solutions.
  • mike95490mike95490 ✭✭✭✭✭ Solar Expert Posts: 8,415 ✭✭✭✭✭
    Re: Converting existing well pump to solar

    Panels, and specialty pump, will cost a lot.

    Obtainng a small generator - in the 2000 watt ballpark, may be your best bet. But running a pump, to fill a pond, that's going to take a LOT of water, time, and fuel.

    And if the generator shuts off while it's powering the pump, several bad things can happen.

    I'd wait for rain, and till then, bank the water in the well.
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  • System2System2 admin Posts: 6,290 admin
    Re: Converting existing well pump to solar
    Welcome to the forum.
    Why is the utility power too expensive?

    Thanks for the welcome.

    I will get the details on depth, etc.and am trying to figure out what else I need to track down from them.

    The problem is not that the utility power is too expensive (although they purchase from a rural coop, so it isn't cheap, but still cheaper per MWh than solar for sure) it is that they are largely publicly funded and there simply is no budget for such operating expenses. I looked at generators but it won't work for the reason above and a couple other idiosyncrasies. So, we are basically going for high capital cost, low operation cost. However, I can get any PV panels we need for free and if the cost is terrible for the rest of it, I can get donations to buy and install the equipment from folks who want that pond filled again, so hopefully it won't be too terrible if we can figure it all out.

    Again, thanks for the welcome and for the suggestions.
  • westbranchwestbranch ✭✭✭✭ Solar Expert Posts: 5,149 ✭✭✭✭
    Re: Converting existing well pump to solar

    IFF, and a big iff, the pond is below the static level of the well ,

    fill a pipe/ hose with water and gravity can take over and siphon the water out of the well. Slow but cheap, yet will take some fiddling.
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  • tmarchtmarch ✭✭ Solar Expert Posts: 143 ✭✭
    Re: Converting existing well pump to solar

    If you can get the solar panels free and make a rack you will have a large part of the investment covered.
    I have no idea of the amount of head you would be looking at, but if it isn't too much, solar can be done pretty inexpensively.
    Sure be cheaper than buying a windmill and less maintenance.
  • TheBackRoadsTheBackRoads ✭✭✭✭✭✭ Solar Expert Posts: 274 ✭✭✭✭✭✭
    Re: Converting existing well pump to solar

    How big is the pond? Any pictures?
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