Confused on which Pump & specs

rguruprasathrguruprasath Registered Users Posts: 9 ✭✭
I'm from India, new to this forum & English is my second language. So kindly excuse me for my bad english and please redirect me if this question was already posted/discussed in this forum.

So here is what I have - An agricultural land about 1 acre and planning for tree plantation now. Plan is to have around 300 plants in the entire acre of land and which requires about 8 liters(~2.5 gal) of water per plant on alternative days(roughly around 2400 liters/650 gal for entire acre). I have planned for drip irrigation and not flood type.

I have a well about 40 feet deep which can supply water for me, but the problem is the distance of land from the well. The well is located about 40 feet from the plantation land. Now my first question is on the pump, considering the things I have, which pump would do the job for me? Right now the pump doesn't have to push water to an overhead tank, its just fetch water from 40' of well and transport to another 40' flat surface. Since the plan is on drip irrigation I guess 40 psi of pressure should be enough to push the water to 40' but correct me if I'm wrong.

Also your suggestions on respective solar panels to support the pump would be great. Since the place is remote, the idea is to put up solar panels and not depend on grid power. Can the pump run with direct supply from the solar panel or does it need a charge controller & batteries? The time of irrigation would be from morning 6.00 to 10.00 am and evening 4.00 to 6.00 pm.

Thanks in advance.

Comments

  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Confused on which Pump & specs

    Here is a pump that would do it, not complicated and runs straight off the panels or with a controller. Easy to repair in the field. By the way, your English is perfect.

    http://legacy.shurflo.com/pages/new_industrial/industrial/agriculture/subcategories/9300.html

    Manual PDF.

    http://legacy.shurflo.com/pdf/industry/solar/911/911-9325-043-101.pdf
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Confused on which Pump & specs

    Welcome to the forum.

    You've asked a seemingly simple question which unfortunately has a rather complex answer. Or indeed answers. :D

    There are three basic factors in pumping water: lift, pressure, and volume. Any one of those can be "traded" against another: same pump lifting from a greater depth will do so at the expense of pressure and/or volume. In other words the available pump power goes into all three factors but can favour one aspect over another as needed.

    40 feet of lateral travel after the lift is not much of an issue. There is some line resistance to be overcome (which will increase with bends, elbows, fittings) but it is usually not a big problem. Most houses will have 40' of lift from the well and another 40' to the upper floor if it is plumbed. Along the way there will be a lot of pipe and fittings. You still get water from the tap, though. :D

    What you are after is a fairly large volume of water; pressure is not much of an issue with drip irrigation (household systems will run down to 30 psi without any ill effects). This presents some other problems, especially if you intend to use solar-direct pumping.

    First question: can the well supply this volume? Keep in mind that if you try to take 650 gallons in four hours that is more difficult for the well to recover from than if you take it in 24 hours. The solar-direct pump will only pump while sunlight is available, so you need a larger volume of water in that time. In that respect you may be better off using a battery-based system to increase the pumping time while decreasing the volume per hour. It's more expensive, but it could save the well running dry unexpectedly.

    There can be another advantage to 24 hour irrigation; less moisture loss from daytime evaporation since about half the water is delivered at night.

    Here are some performance curves for the Grundfos SQF pumps showing the relation between GPM, well depth, and Watts needed for the different pumps:
    http://lib.store.yahoo.net/lib/wind-sun/SQFlex.pdf
    It may help you understand the relationships I was referring to (or it may confuse you).

    A nice thing about these particular pumps is that they can be power by solar directly or battery power or AC power. They are but one option here; not a specific recommendation.
  • rguruprasathrguruprasath Registered Users Posts: 9 ✭✭
    Re: Confused on which Pump & specs

    Thanks much for your rocket quick response. Went through the entire 9300 specs of pump and sounds like a perfect fit for my requirement but the price is way out of my budget. Now I'm looking at shurflo catalogue, meanwhile please let me know if you have any standard models with lesser price in mind which will fit my requirement.

    Thanks again.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Confused on which Pump & specs

    Just to make it clear, neither I nor any of the other moderators work for NAWS. They pay for the forum, so we use them as a base reference for information out of courtesy. :D

    You are up against the #1 problem of all things: cost. None of this stuff is cheap, whether direct-solar powered or a standard pump running from a solar electric power system. SunPumps may be slightly less expensive: http://www.solar-electric.com/sun-pumps.html There is also another brand available overseas which may be more suitable to your needs, Lorentz from Germany: http://www.lorentz.de/
  • westbranchwestbranch Solar Expert Posts: 5,114 ✭✭✭✭
    Re: Confused on which Pump & specs

    I am not sure I understand you drip system and the 'need' for pump pressure.

    I have a drip system for some of my flower beds and it has a pressure reducer (to< 5 psi) so that is does not 'apply house water pressure (35 - 60 psi) to the small drippers. My vision for your system would be a 700 gal tank that is slightly elevated ~ 10 - 20 feet above the ground and that you would use gravity feed to deliver the water to the drippers. If the well can sustain the flow rate you could pump while the sun is up and water at night.
    What is the weather like during the growing season? Do you have any cloudy periods when a solar system will not pump enough water? Maybe you need a 2000 gallon tank for more than 2 days watering...
     
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  • BB.BB. Super Moderators, Administrators Posts: 28,186 admin
    Re: Confused on which Pump & specs

    You may end up with two pumps (or more)... Leave the well pump filling your tank/cistern/pond. And install (one or more) above ground pumps from the tank to pressurize the drip system.

    There are different types of water pumps. Those that are "positive displacement type" (think pistons/diaphragms that move xx volume of water per stroke--and if the water valve is turned off, the pump can actually stall/not turn because of the back pressure) and those that are (usually) centrifugal pumps--Sort of like fans in the air or a vacuum cleaner. They move water when the back pressure is below the pump's output pressure, or just spin when the back pressure is high.

    Many shallow well pumps are centrifugal type pumps. As the pressure increases, the flow reduces, and (to a degree) the electrical power use of the pump drops too. Very easy to connect to a variable flow system, not very expensive type of pump, can usually tolerate sand/dirt a bit better, but can be a waste of electricity (bigger pump than you need turned on when you need "any" water flow).

    With positive displacement pumps, they tend to be more efficient but usually need an electrical pressure switch and a water pressure tank to provide variable flow loads.

    I am guessing, but perhaps a "mixed" system would work well for you.

    Keep your well pump pumping to a tank/cistern (make the water storage tank larger, if needed, and keep tank/water level above ground level). Use a water level switch to control the well pump. Set up the tank so that sand/dirt settles out on one side of the tank and you have a good area to pick up clear water.

    Install one or more smaller pumps (probably positive displacement) so that the pump is below water level with a screen on the pump input (sucking up water above the water level or through a dirty/fine mesh screen can cause all sorts of pumping problems. Water pumps with positive water pressure on the inlet are much more efficient and much less chances to have problems with pulling air into the system and problems with cavitation--creating "vacuum" bubbles that stop pumps from pulling up water and/or collapse and cause excessive wear around the valves and pumping surfaces).

    Depending on the pump, if centrifugal you can just connect the output of the surface pump(s) to your plumbing with a timer/etc. as needed.

    If positive displacement, you can add a pressure tank and pressure control switch to control the motor. Then pipe out to the field.

    If your storage tank is "below ground level"--Then you may have to make a pit to install the surface pumps. Will work fine, but you probably have to install a sump pump and an alarm to ensure that any water leaks/rains do not flood the pit and the pumps.

    Note--You are "paying" for the privilege of pumping to 40 PSI or so for the water. It costs you energy. If you could find a drip irrigation system that runs on 15 psi--you can save some power costs... But, "do the math" first (a paper design with several pumping options/configurations). In your case, the extra power costs may not be a big issue verses the ability to use standard irrigation equipment.

    This is a very complex subject. You have water, pump specifications, AC vs DC questions, pumping during sunlight and/or battery or generator backup, one pump vs two pump solutions, etc. If doing AC, there are electronic devices (VFDs; variable frequency drives) that can allow you to match pump RPM to flow/pressure needs and reduced the surge current during starting (soft start).

    The whole question of trying to do a system that is "solar panel+pump" only vs a solar panel+battery+inverter(maybe)+pump+generator backup+etc... If you can do a "solar+pump" only system--That can cut the cost of your "power equipment" by 3/4's... (when you add batteries, you need more solar panels, charge controllers, possibly AC inverter, backup genset, replace the batteries every 3-5 years, etc...).

    And, you have a different selection of equipment 1/2 a world away from us--So what we suggest may be too expensive/too difficult to obtain anyway.

    I would focus on understanding the pumps available to you (AC, DC, centrifugal/positive displacement, etc.) and see what would be an "ideal" setup for you--Then look at what it takes to power the configuration (solar, batteries, inverter, etc.).

    Using above ground pump(s) that are installed below the water level of the storage tank can really save energy and maintenance issues. However, replacing the well pump with a higher pressure version that can pump direct to field may keep the system much simpler and less costs over all (but may hurt you when looking at costs to power the pump).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rguruprasathrguruprasath Registered Users Posts: 9 ✭✭
    Re: Confused on which Pump & specs

    Thanks for your reply Cariboocoot.
    What you are after is a fairly large volume of water; pressure is not much of an issue with drip irrigation (household systems will run down to 30 psi without any ill effects). This presents some other problems, especially if you intend to use solar-direct pumping.

    First question: can the well supply this volume? Keep in mind that if you try to take 650 gallons in four hours that is more difficult for the well to recover from than if you take it in 24 hours. The solar-direct pump will only pump while sunlight is available, so you need a larger volume of water in that time. In that respect you may be better off using a battery-based system to increase the pumping time while decreasing the volume per hour. It's more expensive, but it could save the well running dry unexpectedly.

    There can be another advantage to 24 hour irrigation; less moisture loss from daytime evaporation since about half the water is delivered at night.

    I agree the volume of water is going to be huge and so I have planned for alternative day irrigation so as to get the well recharged. (I hope the well will get recharged but haven't tested that). But slowly after three months it will twice a week of irrigation. As you mentioned its going to be expensive to consider batteries at this moment and I agree there will be advantage to 24 hour irrigation and we have planned for additional mulching.
  • rguruprasathrguruprasath Registered Users Posts: 9 ✭✭
    Re: Confused on which Pump & specs
    westbranch wrote: »
    I am not sure I understand you drip system and the 'need' for pump pressure.

    I have a drip system for some of my flower beds and it has a pressure reducer (to< 5 psi) so that is does not 'apply house water pressure (35 - 60 psi) to the small drippers. My vision for your system would be a 700 gal tank that is slightly elevated ~ 10 - 20 feet above the ground and that you would use gravity feed to deliver the water to the drippers. If the well can sustain the flow rate you could pump while the sun is up and water at night.
    What is the weather like during the growing season? Do you have any cloudy periods when a solar system will not pump enough water? Maybe you need a 2000 gallon tank for more than 2 days watering...

    I'm afraid that using the gravity feed would deliver less water pressure as the distance grows. That's the reason I'm looking at constant pressure delivery based pumps. Our remote location in India has just three climates, hot, hotter, hottest :D Out of 365 days we get clear sky for around 300 days so I'm confident about the solar.

    Would having an overhead tank change the delivery pump spec? I hope the same pump suggested here would do.
  • rguruprasathrguruprasath Registered Users Posts: 9 ✭✭
    Re: Confused on which Pump & specs
    Just to make it clear, neither I nor any of the other moderators work for NAWS. They pay for the forum, so we use them as a base reference for information out of courtesy. :D

    You are up against the #1 problem of all things: cost. None of this stuff is cheap, whether direct-solar powered or a standard pump running from a solar electric power system. SunPumps may be slightly less expensive: http://www.solar-electric.com/sun-pumps.html There is also another brand available overseas which may be more suitable to your needs, Lorentz from Germany: http://www.lorentz.de/

    ON the whole I have 1000$ of budget for both the pump and solar panels. Shurflo 9300 is about 800$ and that's were I was thinking on the cost balancing. I will take a look at Lorentz & SunPumps.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Confused on which Pump & specs
    ON the whole I have 1000$ of budget for both the pump and solar panels. Shurflo 9300 is about 800$ and that's were I was thinking on the cost balancing. I will take a look at Lorentz & SunPumps.

    I think you're going to have a hard time meeting your pumping requirements on that budget. :blush:
  • rguruprasathrguruprasath Registered Users Posts: 9 ✭✭
    Re: Confused on which Pump & specs
    I think you're going to have a hard time meeting your pumping requirements on that budget. :blush:

    Hi Cariboocoot,

    I realized that I need to stretch my budget after reading this forum and many article regarding DC solar pumps. Most likely I will finalize on Shurflo 9300 as it will solve my current requirement and also take care of future requirement a bit.

    Only thing I'm worried for is Shruflo distributor availability in India and follow up services at later point.

    Thanks for all your inputs.
  • westbranchwestbranch Solar Expert Posts: 5,114 ✭✭✭✭
    Re: Confused on which Pump & specs

    this article has a bit more info on that pump...http://forum.solar-electric.com/showthread.php?8413-shurflo-9300-life-expectancy-duty-cycle
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BB.BB. Super Moderators, Administrators Posts: 28,186 admin
    Re: Confused on which Pump & specs

    Also--These type of pumps (positive displacement and brushed motors--for many) are reliable for home/cabin use. For daily use and many hours a day pumping--They frequently are not.

    Your in-well pump you may want to spend a "lot of money" on it for an efficient/reliable device (pulling pumps from wells are not fun). The surface pumps (from storage to field)--You may get away with "cheaper" pumps that you rebuild/throw away every season because they are on the surface and easier to access.

    Use the specs/documents for the US version of the pumps as your base of education... Then find what is available locally. Getting pumps from a US distributor (or European) may not be cost effective (shipping, customers, insurance, and the higher costs in US/Europe).

    Also, there is the recent thread by "syedbukhari"--Hopefully he can give us more details on his use of a VFD (variable frequency drive) hacked to directly connect to his (large) solar array and drive a (??) ~5 HP three phase pump directly.

    I would think that a VFD+Solar Array driving a 3 phase motor (or a single phase motor with external starting capacitor) would be ideal for your needs... If done properly, it could cut the cost of solar power (vfd+solar) to 1/4 the cost of a full off grid battery based AC voltage system (solar+battery+inverter+vfd?+pumps+etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 8,033 ✭✭✭✭
    Re: Confused on which Pump & specs

    I think to move that much water, you will not be able to meet the $1,000 budget. What will a failed crop cost you ?
    Also, it would be good to rent a pump & flowmeter and a generator for a day, and see what the well recharge rate is.

    40' of lift from well to surface, means your pump has to go underground. You cannot suck water up 40'

    What pressure does your drip system need ? Add that pressure to your 40' of lift. If you can create a mound of earth, and park a a plastic 1,000 gallon water tank on it, 10' above ground, will that give you enough pressure?
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