Small off-grid solar water pump for drip irrigation, 10gal/day

TwoTallPines
TwoTallPines Registered Users Posts: 1
in Solar Water Pumping #1
Hi all, I'm looking to set up a small off-grid drip irrigation system powered by a solar water pump, and I'm looking for any suggestions.

The pump would draw water from a small stream or pond, and would fill a small cistern/water barrel (<50gal). The cistern would supply a drip irrigation system by gravity.

I'm guessing the whole system would not need to draw more than 10gal/day, although working in the 10-20gal/day range wouldn't be bad. The whole thing would be placed to minimize distance from stream to barrel.

Any advice/guidance that you can share would be much appreciated!
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Re: Small off-grid solar water pump for drip irrigation, 10gal/day

    Welcome to the forum,

    Not enough info to design the system...

    The pump will need to be very near (or in) the stream. How far uphill does it need to pump? How far will the solar panel be from the pump? Is there any chance that the pump could run dry? (that will ruin some pumps).

    You should be able to do this without a battery, but you may want to insert a linear current booster between the solar panel and the pump.

    Next question is budget... durable quality pumps are expensive, but there are a few small pumps that are quite cheap. You get what you pay for. Search Amazon for "12 volt submersible pump". You will find quite a few for under $50. What they don't tell you is that most of these pumps have a useful life of just a few hundred hours.

    --vtMaps
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #3
    Re: Small off-grid solar water pump for drip irrigation, 10gal/day

    I tried this and there is not enough pressure (in a gravity feed from a cistern) to get the drip emitters to function.

    I (at first) thought I solved that problem with using the tiny 1/4" drip-system "valves" instead of emitters and just opened then up a tad but still could not get the correct pressure at the end of the line; especially as the cistern started to get closer to being empty. And BTW my cistern is up on a 12' tower so in theory it should be putting out about 5psi which works for toilets (although slow to fill), faucets and shower heads (drilling out the water saver stuff in them).

    Then I went to a 1" pvc (sc200) main line around the property and then had the drip lines connected from that. That setup helped but still did not achieve what I was hoping for. Granted, I have about 1200' of actual drip line and 280 .5gph emitters so I am sure that makes a difference in comparison to what you are doing.

    End result was that I gave up and just ran the system directly from the shallow-well pump that I used to fill the tank anyways. It is on a timer for 1 hour a day and yeah it draws some power cause it is a cheap $89 harbor-freight "chinese rated" 3/4 hp pump, but mid-day when the sun is shining (usually) it is a wash.

    So, you still have to determine what pump to get (many on here can advise) but I would give up on the direct cistern/drip idea. Just run the drip directly from the pump and save all of the hassle I went thru.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Re: Small off-grid solar water pump for drip irrigation, 10gal/day

    Drip emitters have a input pressure range, and the supply tube has limits as to how many emitters it can feed.

    If you can design your system around the limits of the gear, and use the proper filters to prevent the emitters from getting clogged with sediment, you will be on your way.

    http://dripworks.com/ has a good online catalog with lots of info about system requirements
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