Agriculture well application in the Caribbean

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bungaknotty
bungaknotty Registered Users Posts: 2
in Solar Water Pumping #1
Hi,

I run a farm in the Caribbean. Currently, I use a generator to power a 1hp pump 230 VAC. I would like to transfer to a solar off grid system. My well is 40' with a 6" hole and I use drip irrigation to serve about 6 acres of land. What would I need to convert to a solar system for this application. Is it best to buy a dc pump? Responses would be greatly apprciated.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
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    Re: Agriculture well application in the Caribbean

    Since a direct solar PV system would require a very large battery bank to run the pump when the sun is not giving you enough power, can you use the pump to fill an elevated tank during day and use gravity feed from that tank to supply the drip system?
    A tank would likely be less expensive than batteries.

    How may gallons are you currently using per day?
    SMA SB 3000, old BP panels.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
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    Re: Agriculture well application in the Caribbean

    What are the running amps of this pump, is it single phase or 3 phase, and what is the greatest number of hours it must run each 24 hour day?
    Hint: This could get VERY expensive!
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #4
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    Re: Agriculture well application in the Caribbean

    I'd look at two things. 1) if you can get by with only watering when the sun is shining (this works well for me) and 2) if you can make changes to get adequate water with less HP. In general, you need to know the number of gallons per day and the pressure needed.

    I am available for custom hardware/firmware development

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #5
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    Re: Agriculture well application in the Caribbean

    To give you something to think about (large scale irrigation with solar):
    BB. wrote: »
    Some discussions about VFD (Variable Frequency Drives)... Basically a variable frequency inverter with (typically) three phase output. Used to soft start motors (handy for 3 phase well pumps, or pumps with well head starting capacitor) and can also turn an AC motor into a variable speed motor (very handy for pumping applications).

    WELL PUMP and Inverter QUESTION
    Wind/solar for large scale pumping etc (out of my depth!)
    could use knowledge - using Gould jet pump - transfering from 230vAC to ? DC (new link/thread 10/27/2012)
    Help required to design off grid system (information on possibilities to connect "standard VFDs direct to solar panels) (new link 1/13/2013)

    Otherwise, there are some good pumps that connect directly to solar panels--A couple to look at:

    http://www.solar-electric.com/grsoposuwapu.html
    http://www.solar-electric.com/sun-pumps.html
    http://www.solarpumps.com/

    If you can figure out how to do most of your pumping directly from solar panels (no batteries)--You will save a lot of time and maintenance.... Very roughly, runnign the same load from an off grid solar+battery+inverter system is (very roughly) ~4x the cost for the solar power components as running directly from solar panels themselves. And batteries that need monthly watering/inspection plus replacement every 3-7 years or so.

    Of course, pumps and equipment that can run directly from solar panels is not cheap either... So it is a good idea to do paper designs of several system options and see what works best for you.

    Conservation will also be your friend... Off grid solar battery power is about ~10x the cost of utility power (at least in the US)--So by using very efficient pumps and low pressure delivery systems, you will be saving lots of money too (utility or solar power).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bungaknotty
    bungaknotty Registered Users Posts: 2
    #6
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    Re: Agriculture well application in the Caribbean

    My pump is 6.7a 3 phase 230VAC 10gpm. I am willing to pack away my pump for a dc equivalent if that works out more cost efficient. I only need to pump water during the day. Do I just look at a dc equivalent pump for this application?

    I am also thinking about putting a timer on the pump to turn it off and on during the day. Also the possibility of solenoid valves on each section of my field so that I can water to the requirements of each crop. Would I need an inverter for this?

    What would the costs be roughly for solar panels and pump for an application like this?
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #7
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    Re: Agriculture well application in the Caribbean
    bungaknotty wrote: »
    My pump is 6.7a 3 phase 230VAC 10gpm.

    A 3 phase motor is potentially a good fit. You can add a 240VAC (or DC) single phase to 3 phase VFD inverter and get both soft start and variable speed. Maybe ~2000 watts of panels and no batteries could work.

    I am available for custom hardware/firmware development

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #8
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    Re: Agriculture well application in the Caribbean

    Email the wind/sun store here on the forum. Ask them for design help to run a DC pump, like the Sun pumps they sell. They can ship to the Caribbean. Keep this really simple and safe and stay away from VFD or anything that has alot of electronics to fry when you get you afternoon lightning shows. Good Luck ! Also the fine DC pumps from Grundfos are at the wind/sun store that can run from DC panels or 120/240vac.

    bungaknotty wrote: »
    My pump is 6.7a 3 phase 230VAC 10gpm. I am willing to pack away my pump for a dc equivalent if that works out more cost efficient. I only need to pump water during the day. Do I just look at a dc equivalent pump for this application?

    I am also thinking about putting a timer on the pump to turn it off and on during the day. Also the possibility of solenoid valves on each section of my field so that I can water to the requirements of each crop. Would I need an inverter for this?

    What would the costs be roughly for solar panels and pump for an application like this?
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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