Solar water pump system advice needed

machinemanmachineman Solar Expert Posts: 129 ✭✭✭
I'm looking to build a simple (and cheap) solar pump systemn to slowly fill a large tank. The water source is a spring holding pond and the 2500gal tank is about 200ft away at +125ft vertical elevation. I don't need a lot of GPM since the tank will be a large reserve. The tank will have a float valve so the pump will need a pressure shut off switch. The above ground pump will not need to syphone more than 8ft. Can anyone recommend a simple 12V pump and pole mounted panel set-up? I was looking at the shurflo pumps but need help pairing one up with a panel for my application. Also would a battery with voltage regulator give me a little extra on cloudy days?

Thanks.

Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

Comments

  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Solar water pump system advice needed

    Machineman,

    Solar water pumping ain’t my forte. However, the following information may help you get headed in the right direction.

    The combination the 8 ft siphon, the friction loss in 250 ft of pipe, the 125 ft of lift and, most likely, the friction loss in the 8 ft siphon pipe and the 125 ft of lift pipe will add up to a substantial total dynamic head. The 125 ft of lift alone is +4 bar (~ +58 psi), and low-flow-rate friction losses will likely add another bar or two, for a total of ~87 psi.

    You didn’t indicate your projected daily watering requirement. Assuming it’s ~250 gallons per day, and that you average ~four full hours of daily insolation, you’ll need a pump that can deliver one gallon/minute from the pond, through all of the pipe, and up to the tank. The specs for the Shurflo Model 8000-543-138 12 V pump suggest that it could handle that rate and the (gu)estimated total dynamic head pressure.

    See: http://www.shurflo.com/pages/new_industrial/Industrial/gen_industrial/genind_doc_sum/8000-543-138.html

    Kyocera’s old solar water pumping guide looks like it might be useful in addressing these issues. You can download the pdf file from here: http://www.solar-electric.com/PDF_files/Solar_Pump_Guide.pdf

    I’d estimate that you’ll need at least a 130 W (STC) PV module, and probably a 170 W (STC) module, to power the pump for ~one GPM. Examples include the Kyocera 130 or a pair of Kyocera 85’s wired in parallel. The twin 85's might be a better overall choice, as they could be wired in parallel for 12 V nominal or in series for 24 V nominal. The latter would allow you to consider a 24 V pump.

    See: http://store.solar-electric.com/kc-120.html
    And: http://store.solar-electric.com/kysokc85wa12.html

    You’ll likely need a current booster between the PV module(s) and the pump. Something like this might work: http://www.solarconverters.com/ppt15.htm

    Unirac makes top-of-pole mounts for PV modules: http://store.solar-electric.com/pountopofpos.html

    You’ll also need wire and fuses. Adding a battery may increase system flexibility, but it also increase system complexity, cost and maintenance. You’ll need to consider the best balance for your needs.

    HTH, and HNY!
    Jim / crewzer
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Solar water pump system advice needed

    Thanks for the reply.   Would a 24V system be better? I'm starting from nothing so I can go either way, 12V or 24V.   Assuming cost is the same.

    Also that pump has a 100psi demend switch. Based on your load estimations this would be enough to keep the pump running to overcome the friction/elevation load until the fill tank float closes.  But is this to much for the black 3/4" poly tubing I was going to use with clamped slip on fittings?

    My watering requirements will most likely be <150gal a day. Its for a cabin that's not a permanant residence. That's why I'm putting in a 2500gal tank so I could use more or less with out draining it. Those solar panel are expensive!!

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Solar water pump system advice needed

    If the pump is a significant distance from the PV array and controller, the power loss in the wiring to a 12 V pump would be 4X that in the wiring to an otherwise equivalent 24 V pump. You'll have to crunch the numbers for various combinations of wire- and pump costs. Here's a link to a 24 V pump: http://www.shurflo.com/pages/new_industrial/Industrial/gen_industrial/genind_doc_sum/8000-853-238.html

    This link for another pump seems to suggest that a 130 W module is the minimum for 180 ft lift (~5.5 bar) and ~1.5 GPM (~87 GPH): http://www.shurflo.com/pages/new_industrial/industrial/solar/doc_sum/9325-043-101.html

    I think we're in the right ball park w/r/t PV size...

    You'll need to check on pressure specs for the tubing you plan to use. This one I found on the 'Net is rated at only 60 psi: http://www.dripirrigation.com/drip_irrigation_info.php?cPath=36_136&products_id=1005 However, the friction loss in 3/4" poly should be lower than that in the 1/2" Schedule 40 I sort-of-assumed in my earlier post.

    Good Luck!
    Jim / crewzer

  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Solar water pump system advice needed

    Thanks, The panel will probably not be more than 50ft from the pump.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar water pump system advice needed

    don't forget to get the right size wire for your project as too small of wire will cause a large voltage drop and thusly a large power loss due to the wire being undersized. here's the link if you would like to figure this yourself:
    http://www.wind-sun.com/smf/index.php?topic=1477.30
    now if you don't have access to excel or the clone of excel or you are just having difficulty you can let me know and i could calculate it for you. you would have to let me know which voltage system you'd go with, 12v or 24v, and the current that is needed to go xx number of feet(assumed to be 50ft by your input).
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Solar water pump system advice needed

    That excel calculator is neat. Thanks.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar water pump system advice needed

    you're welcome.
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Solar water pump system advice needed

    Update on this project, and follow up question.

    I got more accurate measurements and calculted by dynamic head to be about 54psi. The friction loss is almost nothing (<1psi) becuase I'm going to use 3/4" PVC which is plenty large for my low GPM needs. I'm leaning towrds a 24V panel and pump to reduce the current and will lower the cost of the needed current booster. I calculated my required wattage using the pump mfg table, 24V line loss, and my 54psi head, it comes out to around 82watts.

    So, if I get two 12V KC65 (65w) panels and run them in series then I should be all set. Except....... The panel Max voltage is 17.4V each, so doubling would be 34.8V. So how does that work for a 24V pump? I'm I missing something?

    Parts:
    Pump Shur-Flo 8000-853-238, 24V, 100psi demand SW
    Panel KC65 65watts 12volts (need 2)
    Current Booster 7amp linear 12-24V

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Solar water pump system advice needed

    MM,

    The pump is 24 V "nominal". I'm not able to open the product spec files, but I suspect the operating voltage is probably something in the 21 V to 35 V range. The PV module's Vmp may be 17.4 V, but that's under STC lab conditions. You'll probably see the series pair of modules operating in the ~30 V range once they heat up in the Sun.

    HTH,
    Jim / crewzer
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Solar water pump system advice needed

    Thanks.     One more question.

    Should I choose a panel based on the pumps required power at a given PSI or the current draw at a given PSI?   The reason I ask is that the solar panels max wattage meets my pump requirements but its max current output is falls short of what the pump says it needs at the givev PSI.

    Example:

    If I need 40PSI then the pump specs say it draws 5.6amps and is 67.2W at 12V.   The panel is 85watts so I should be OK right?  However the max current from the panel is 5.02amps.   So which is it? I have run into this with several pump and panel combinations.

    Pump Specs:  (Shur-Flo  8000-443-136)
    Volts PSI GPM Amps watts(I calculated 12V x amps)
    12 20 1.57 4.2 50.40
    12 30 1.48 4.9 58.80
    12 40 1.38 5.6 67.20
    12 50 1.3 6.9 82.80
    12 60 1.23 7.2 86.40

    Panel specs: (KC85)
    85watts, Max 17.4V, Max current 5.02


    Thanks again.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Solar water pump system advice needed

    I think I've got this right: You'll need to choose between powering the pump directly from the PV module or using a pump controller ("linear current booster") between the PV module and the pump.

    If you power the pump directly from PV module, you'll need a module rated to supply all of the current required by the pump. The panel will operate at a voltage basically defined by the module's output current and the resistance of the pump motor and the associated wiring (V=IR).

    If you use a controller between the PV module and the pump, you should be able to use a smaller module as the controller will convert "extra" voltage from the module into additional current -- sort of like an MPPT charge controller. This is apparently very helpful on cloudy days, when the PV voltage can be high because the module isn't heated up by the Sun, and the PV module current is low due to low insolation.

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Solar water pump system advice needed

    Hi Machineman.
    Have you progressed any further with your project? How much money are you looking at? I ask because I'm looking at setting up a similar system and would like to know what I'm getting myself into. We have a spring above the house, but not far enough above to get a resonable pressure. We get about 15psi and would like it to be at least 50psi. My thought is to put a tank up higher on the hill and pump the water into it when the sun shines. I can go pretty much as high as I need to as long as I buy enough pipe.

    Thanks,
    John
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Solar water pump system advice needed

    I think I have it all figured out and will probably start this spring when the weather is better. The higher you go with the tank the more its going to cost you becuase of the required panels to supply enough power to pump up. I would go higher with mine if I could but my property line limits that. I decided to go cheap for now and upgrade later if needed since its not a primary residence. The tank will have plenty of reserve and could slow fill while I'm not there. From the tank to my cabin I will only have about 15psi also so maybe later I will add a presure pump when I eventually put panels on the cabin for other use. Unfortunalty my spring is below my building pad.

    Pump $70 (0.9GPM)
    65w Panel $330
    Current Booster $78
    Sch40 PVC Plumbing and fitting >$150
    2500gal tank $1100
    Panel mount $ ??
    Renting trencher to put pipe in. $ ??

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Solar water pump system advice needed

    OK. I hope you'll report back with results after you complete the installation. The feedback will be helpful to both us as well as others with similar needs.

    Best of luck!
    Jim / crewzer
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Solar water pump system advice needed

    The project will probbly start in a month or so. My property is 4hrs away from my primary residence so I only visit once a month. The painful part will be digging the pipe trench. The rest will be fun. I will update it then with progress and pic's.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

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