Solar pumping from a well? Help! I'm new!

SystemSystem Posts: 2,511 admin
Hi all and thanks in advance for your help. I will spell out my situation and what I want to do and I hope someone here can give me some advice.

I am the director of rustic style rehabilitation facility in a very dry region of Texas. I am trying to move the facility towards self sufficiency. One of my main problems is water. Our current well is a low producer and only suffices for daily water needs and very little irrigation of a small garden. I want to expand the agricultural possibilities of the facility but I need a dependable water source to do this. The simple solution would be to have a very deep well dug for irrigation via electric or gas pump. But I also have another option which I like better. There is a dry stock pond on our land that years ago had a windmill on it to keep it full. The pond is about 1/3 acre in size. I estimate that it will take about 500,000 gallons of water fill it up. I know that in years past a windmill was able to maintain this pond, so I am assuming it will still hold water once it reseals. If I can establish a reliable pumping system the will maintain and slowly fill this pond, then I will accomplish two things instead of one. First I will be able to pump out of this pond for irrigation purposes. Second I will be able to grow fish in the pond for food. It will also provide a new activity (fishing) for patients that are going through rehab.

I want to state here that my facility is a free will supported operation and we offer our services and treatments for free. We operate on an extremely tight budget and have minimal resources for projects such as this. But the more we move towards self sufficiency, the better our chances of survival in a failing economy and the longer will be able to offer our services free of charge.

OK, here is where I am at right now. I have already had a new (3 GPM) well dug next to the pond to put a pump in to maintain the pond. Now I am trying to decide between a windmill or a solar pumping system. I am not looking for a system that will fill the pond quickly. I just need a system that will maintain the pond and add to it slowly. We do get some rain and this is where most of the water to fill it up will come from.

Here what I am looking for. I am wanting an economic, reliable, low producing system. My first thought was that since the windmill has been around for hundreds of years, it would be the way to go. Some people have advised me windmills are high maintenance and that solar pumping is a better way to go. I have done some research on DC submersible pumps and there are several different types to choose from like the SunPump SDS-Q-128 and the Shurflo 9300. Then there are difference types such as diaphragm or centrifuge and stuff like that. There seems to be tons of options and very little (un-bias) information about which one is better.

If I go solar, I need to know how long I can expect a pump to last in my situation where it will run almost continually. I need to balance the cost of pump replacement against the cost maintaining a windmill. If a need to know if a windmill is better for long term use. And I have not even touched on the issue of solar panels, though it seems that wattage will be the most relevant fact there.

I know I have opened a can of worms with all these questions, so let me narrow it down. I have a well that is 60 feet deep with the water level at 30 feet. It has a maximum water production rate of 3 GPM. In order to keep the well from running dry and burning up the pump I think a pump that can pump around 2 GPM would be about right. I need a pump that is not terribly expensive to buy but will last a long time under constant use. The well water is clean but has a high calcium content. I also need to know what type and wattage of solar panels would give me the best production with a given pump and whether they should be connected directly to the pump or via a controller of some sort.

Thanks for the help.


  • EcnerwalEcnerwal Solar Expert Posts: 101 ✭✭
    Re: Solar pumping from a well? Help! I'm new!

    Good to have the depth, static level and production numbers.

    A few additional questions:

    Diameter of well casing?

    What happened to the well the windmill used to pump from?
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Solar pumping from a well? Help! I'm new!

    What are you currently using to provide power to the rest of the facility? And why can't you power the pump from the same source?
    Are you planning a solar PV or wind power system in the near future?
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,027 ✭✭✭✭✭
    Re: Solar pumping from a well? Help! I'm new!

    Along with answers to previous questions keep in mind that if you go solar for pumping it is not "continuous use" as the pump will not be running when the sun is down or obscured.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 30,049 admin
    Re: Solar pumping from a well? Help! I'm new!

    As Dave says, one option is to use the pump with solar panels only... But it will only be running 8 hours a day or so... 2/3rd's of the day, there will be no pumping, so for a low capacity well, this may not be enough.

    On the other hand, using batteries to spread that out to pumping 24 hours per day -- makes the system much more complex and expensive (probably at least 2x more expensive for same amount of power, plus battery replacement every 4-10 years, plus monitoring to make sure you don't run the batteries flat, adding distilled water, keeping clean, etc.).

    However, if the wind powered pump was able to keep up--unless you have 24 a day wind--there may be enough water in 8 hour a day pumping (2gpm*60minphr*8hrperday=960 gallons per day (very roughly) ito be enough...

    In the end, you will probably have to cost out the various solutions and see what works best/most cost effective/donations available would work best for your situation.

    And, the old "what if" there is not enough sun/wind power--can the system you choose easily allow you to connect a reasonable sized genset to get water for you?

    1. solar PV well pump (no batteries)
    2. solar + batteries
    3. wind turbine powered (perhaps, find unused tower+turbine)
    4. compressed air type well pump (either wind turbine or electric powered)
    5. new deep sell and then review all of the options again

    And, it is not quite clear if you have grid power available or not--In the end, cost wise, conservation (and making energy efficient choices in appliances, well pumps, etc.) will reduce your bills and an be greener in the end. If you have utility power, then the hands down best solution would be Solar Grid Tied solar inverter (no batteries). Most cost efficient and least maintenance of any solar electric solution. Solar GT will not provide backup power if the utility mains are down--but it is a very "green" and cost effective choice (assuming your utility allows GT Inverters and has some sort of reasonable Net Metering plan). And GT solar usually qualifies for the most tax credits/rebates (perhaps a donor can take the tax credits if your facility cannot).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar pumping from a well? Help! I'm new!

    Thanks to all. I will try to answer questions from several responses. My well casing is 5". Grid power is 800 feet from the well. The former well was drilled around 80 years ago and has collapsed.

    I have been doing constant research on this issue and let me tell you what kind of system I have in mind and you can tell me if you think it will work or not.

    I am thinking about going with a Shurflo 9300 submersible pump. It peaks out around 2 GPM so it should never run the well dry. I plan to place it at 55 feet of depth so it will be safe and not pick up any debris from the bottom of the well. The water level of the well is at 30 feet so even with some draw down this pump will not struggle. I do not plan to run it into a elevated storage tank at this time, it will just run straight into the pond. I plan to power the pump with two 50 watt PV arrays in combination with a Shurflo 9300 Basic Pump Controller which is supposed to increase pump production %30 over direct PV to pump systems. Estimates are that this system can produce 1000 gallons on bright sunny days. 1000 gallons a day would be enough to maintain the pond and add to it just a little. Evaporation and ground absorption rates are very difficult to calculate so I will have to just see what happens after the pond is full. The shurflo 9300 is stated to last 2 to 4 years, but I am not sure if they are talking about the motor or the diaphragm (which can be replaced).

    I estimate this system to cost me about $1,400. (Shurflo 9300 =$670 + 2-50 watt PV arrays = $600 + Shurflo 9300 Basic Pump Controller = $130 Total = $1,400).

    Now if I were to go with a grid powered system as some suggested, let me tell you my thoughts on that and you can tell me if I am right or wrong. To pull grid power to the pump I would need 800 feet of 8/2 UF copper wire with a ground to power a 110V 1/2hp submersible pump. I might get away with 10 gauge wire but at that distance I think resistance might cause the wire to heat up. 8/2 UF with ground cost about a dollar a foot, so that would be $800 right there not including the cost of renting a trencher to bury 800 feet of wire. A 1/2 HP pump cost about $300 to $400. Now an AC pump is going to run this well dry in about 10 minutes, so I will have to install some type of control to turn it off when the water gets to low and back on again once the well has recuperated. I don't know for sure but I have sneaky suspicion that this control system is not going to be cheap. So with just the pump and the wire I am looking at over $1000. Now I have to calculate how much the electric cost will be to run this pump. I estimate that the well can safely produce 3000 gallons a day. My estimate based on a 1/2 HP pump and the cost of my grid electricity (.10 cents per KWH) is that it would cost me about $15 a month to run this system.

    Now from where I am standing and if my calculations are right ( I am depending on you to correct me if I am wrong), the cost of the solar system I propose is the same as or close to a grid system. The cost of operating the solar system is zero versus $180 a year for the grid system. The major difference is that with the grid system I will be getting three times as much water as the solar system with my current well and at some point the pond will be full and the grid system will have to be turned off.

    The one thing I don't know is how long an AC submersible pump last vs a DC pump like the Shurflo 9300. I suppose it will last much longer because it will not be in constant operation and I have to calculate the cost of DC pump replacement (2 to 4 years), against the savings I will get from a solar system. In the end I think they will end up costing about the same so I think the grid system is better because I get more water from it.

    If you guys agree with my assessment and think I should go with a grid system, can you give me some ideas about a control system for the pump to keep it from running the well dry and burning up the pump? Thanks

    on a side note, I found this package on ebay. Tell me what you think about it.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Solar pumping from a well? Help! I'm new!

    I know of someone who runs a 9300 shurflo in a deep well serving a family of four. The pump has been in the well for ~10 years without a failure,,, just FYI.

    I have run a 9300 in the lake for 2 years now without a problem,,, but we use very little water,, just two of us.

  • mike95490mike95490 Solar Expert Posts: 8,610 ✭✭✭✭✭
    Re: Solar pumping from a well? Help! I'm new!

    You could also run AC power, and use a 24VDC powersupply (fancy battery charger) and run a 2 GPM DC pump 24/7 I'd still install a float switch for dry seasons when the well may run dry.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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    gen: ,

  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Solar pumping from a well? Help! I'm new!

    I'm a belt and suspenders kind of guy...

    I would dig the trench and run the grid power to the well, and while I was at it I would toss a PVC water pipe into that trench as well - just in case I needed to get water from that well back up to the building or vice versa.

    Did your price estimate for the solar pumping system include the mounting for the panels and the wire and whatnot?
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Solar pumping from a well? Help! I'm new!

    Virtually all the parts of the shurflo are replaceable, including the diaphragms, bearings, brushes, valves at fairly reasonable prices.

  • EcnerwalEcnerwal Solar Expert Posts: 101 ✭✭
    Re: Solar pumping from a well? Help! I'm new!

    You can always throttle a 1/2 or (1/3 - even better, and usually cheaper to buy) hp grid-connected pump to whatever flow rate makes you happy. Just takes a valve in the outflow pipe - costs very little indeed. Counterintuitively enough, the power consumption also goes down when you throttle the flow rate back (at least for a centrifugal pump, which most are going to be).

    As such, my suggested control system is one valve, with occasional application of a bucket and a watch. A low-water cutoff in the well would be nice. Level switches in wells are prone to problems, however. With a restrictor valve on the outflow to get the rate down, the most practical and least likely to screw up low level control would be a pressure switch on the pipe before the restriction valve, adjusted to cut the pump power off (until manually reset) if the pressure drops below the pressure you get when it's pumping properly from a well-full of water into the restrictor valve when that is properly set for the right flow rate.

    You should be able to use the common (thus inexpensive) well-trol type control for this - in normal use it needs to be manually held on until pressure builds up to the lower setpoint (20, 30, 40 psi) and then turns itself off when the pressure gets to the high setpoint (40, 50 60 psi). If pressure ever drops below the low setpoint (just below where it turns the pump back on) it again needs to be manually held on. In your application you'd adjust (get an adjustable one - there are both adjustable and fixed types) the low setpoint to be just below the pressure when pumping 1 or 2 gpm, and the high setpoint would never be reached. If the well ran low, the pump would suck air and the pressure would drop, shutting off the pump until someone manually turned it back on.

    A normal, properly designed deep well pump actually lasts longest if run for long periods - turning it off and on shortens the life of the motor, especially if turned off and on in short bursts. Continuous run should be fine, so long as you have water.
  • jacobsjacobs Solar Expert Posts: 72 ✭✭
    Re: Solar pumping from a well? Help! I'm new!

    If you started out with a good used windmill, it would probably last at least 30-50 years w/o any repairs. Pump leathers would require ocassional replacing but are very inexpensive and easy to replace if you have an open top cylinder. Windmills do require annual oil changes and lube. You might want to check for help there. Some of the guys on that forum are in Texas and might even donate some help and or parts to the cause.
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