Well Pump & Battery Array sizing

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donquixo
donquixo Registered Users Posts: 4
in Solar Beginners Corner #1
I am planning to install two 250w 12v solar panels that would feed 4 @ 6v 225ah batteries in 2 strings. The battery array capacity should theoretically be 5400 watts. [correction--Actually 5,400 Watt*Hours. -BB]

The only thing I want to power is my well pump. It turns on 4 times a day, for about 2.5 minutes to fill the water tank. It's a 230 volt well pump and it pulls 19 starting amps (for about 1 second), after which it drops down to 13 amps for the remaining 2.5 minutes.

I was thinking of using a Trace C12 Charge Controller . What kind of inverter would i need - what specs would it need to have, a NEMA L14-30 plug comes out of the transfer switch to the well pump. Would this setup even work?

Many thanks
donquixo
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
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    Re: Well Pump & Battery Array sizing

    Welcome to the forum Don!

    By the way, I corrected your post--It is Power*Time or Watt*Hours for battery capacity... Watts vs Watt*Hours is like the difference between Miles per Hour and Miles Driven.

    It is a common typo/mistake that we all make when starting--And I have made once or twice in my XX,XXX posts. :blush:

    By the way, roughly, where are you located? Folks can probably give you a better answer on hardware based on what is easy to get for you (US, Europe, etc.?).

    19 amps at 230 vac is a lot of current/power...
    • 19A * 230 VAC = 4,370 VA (volt*amps--Which is different than Watts).

    So--the first question is it practical for you to change the pump to something smaller/less surge? Probably not. A nice off grid / solar panel ready pump (solar, battery, even AC generator backup) would probably cost you more than $2,000... But its maximum power input will be closer to 1,000 Watts/VA maximum--Which can save you a lot of money on building a solar power system (smaller batteries, inverter, less solar panels, etc.).

    Another possibility is to use a VFD--Variable Frequency Drive. These can "soft start" a well pump and even vary the RPM (VFD Frequency) to better optimize pump power/speed to actual amount of water needed.

    And there are options--Pump to a cistern, then use a small DC pump to presurize household water with a small pressure tank.

    Back to the question--What is it you are looking for? Emergency backup power for days, weeks, months (each can have a different answer). Is this a remote site with no utility power or too costly to run lines? Are you looking at saving utility costs? etc...

    Will the pump be unattended? Do you need pumping power 24x7, or just during daylight hours (a set of solar panels attached to a pump is much less costly and less maintenance that creating an entire battery bank+inverter system--if this is the only power draw)...

    What is the well (depth to water, depth to end, diameter, rate of flow you need, etc.)? Any issues (sand?).

    Sorry, more questions than answers at this point.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #3
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    Re: Well Pump & Battery Array sizing
    donquixo wrote: »
    I am planning to install two 250w 12v solar panels ...

    I don't think I have ever seen 12V nominal panels in that high of wattage, do you have their specs?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Well Pump & Battery Array sizing
    Photowhit wrote: »
    I don't think I have ever seen 12V nominal panels in that high of wattage, do you have their specs?

    That would indeed be unusual as 250 Watts divided by 17.5 typical Vmp gives and Imp of about 14 Amps.
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  • donquixo
    donquixo Registered Users Posts: 4
    #5
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    Re: Well Pump & Battery Array sizing
    BB. wrote: »

    Back to the question--What is it you are looking for? Emergency backup power for days, weeks, months (each can have a different answer). Is this a remote site with no utility power or too costly to run lines? Are you looking at saving utility costs? etc...

    Will the pump be unattended? Do you need pumping power 24x7, or just during daylight hours (a set of solar panels attached to a pump is much less costly and less maintenance that creating an entire battery bank+inverter system--if this is the only power draw)...

    What is the well (depth to water, depth to end, diameter, rate of flow you need, etc.)? Any issues (sand?).

    Sorry, more questions than answers at this point.

    -Bill

    Bill, awesome first reply, your input (and correction) is much appreciated. I am living in the US, western Connecticut for those of you who have hardware suggestions.

    The answer to your questions is a bit complicated, as I was trying to approach my battery-bank/solar in phases. So, here goes.

    PHASE 1. The most demanding electrical unit in my house is a 450' well pump (sorry, but that's all the information I have on it after I bought the house, no sand issues). Pump is unattended, would need water tank to fill just during daylight hours. Without replacing it for a somewhat costly 1000w solar well pump, I wanted to see if I can put together a battery/solar/shoreline system that could keep it going when the power goes out. There is also an oil-fired boiler and a couple of selected outlets that are on the same transfer switch electrical panel as the well pump, but I would assume their electrical pull to be insignificant enough for this phase. My main concern would be to have the water.

    So I thought of purchasing a couple of the Grape Solar 250w solar panels (thanks for the comments guys, they're actually 30v it seems), a charge controller and couldn't figure out the transformer. You can find the spec here:

    http://content.costco.com/images/content/misc/pdf/655648.pdf

    My intent was to start off with a couple of batteries and panels and see if I can achieve the goal of running my well pump, and then for how long I could do it without having to resort to a generator or an oversized battery bank as opposed to just a couple. Not really looking for saving on utility costs yet.

    PHASE 2 In the next phase I wanted to expand the battery bank and hook it up to a shoreline supply (to the electrical panel) to keep the batteries charged in case the solar panels couldn't keep up. The reason for extra batteries is to cover the outlets mentioned above that are part of the transfer switch panel, as I'd have a refrigerator and laptops and lights on those circuits, and possibly other minor appliances. Not concerned about lowering utility costs, but if panels allow to feed back to utility company, that's great. I've also seen commercial grade UPS backup systems coming of the server racks at a discount and thought it might be worth looking into, as they have built in iverters. One example is Smart-UPS RT 6000VA:

    http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SURTD6000RMXLP3U

    As you can see it has NEMA L14-30 output, which I need for my transfer switch, but also has NEMA L6-30R input, which I'm not sure how to accomodate in this setup. I've also seen used external batteries for these, which can be daisy chained to this unit in a string of up to 10. Maybe some of you had experience with these in a residential setting similar to what I'm trying to describe. They seem HEAVY and bulky. This is something I've been considering as an option to use instead of the 6v 225AH batteries. I wonder what you guys think about this.

    PHASE 3 See if I can sustain the elements in phase-2 by adding a couple extra solar panels and batteries for 2,3...7 days or indefinitely, without going overboard with the number of batteries I have to store, vent, maintain and replace after few years as well as other expensive equipment.

    I hope this helps convey what I'm trying to do. And I'm seriously wondering if replacing the well pump is a viable option. So, Bill, guys, please fire away.

    Don
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #6
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    Re: Well Pump & Battery Array sizing

    Is your pump 120V or 240 V any disclosure in the paperwork when you bought the house, as to it's HP rating ? Can you call the old installer of the well / pump and see what their records show ?
    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 ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #7
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    Re: Well Pump & Battery Array sizing

    Just to get an idea of the dificulties of running a well off solar, we have a somewhat current thread about someone who is trying to do this Here.

    http://forum.solar-electric.com/showthread.php?18756-48V-Off-grid-system-for-down-payment-on-6-Acres-help

    We may have scared this poor guy off, he had already purchased some equipment. Your looking first this is a good thing!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • donquixo
    donquixo Registered Users Posts: 4
    #8
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    Re: Well Pump & Battery Array sizing
    Photowhit wrote: »
    Just to get an idea of the dificulties of running a well off solar, we have a somewhat current thread about someone who is trying to do this Here.

    http://forum.solar-electric.com/showthread.php?18756-48V-Off-grid-system-for-down-payment-on-6-Acres-help

    We may have scared this poor guy off, he had already purchased some equipment. Your looking first this is a good thing!


    Oh boy, :blush:, I see what you mean.

    With a hat in my hands let me say this, where do I start? I just want to have the well pump going on its own. What's the proper, most economical and sane way to accomplish this with the right equipment?

    The startup and running current draw I measured myself - let the tank drain and kick in the pump and then timed the process to 2:30 mins. By the tank the installer wrote 1HP, new 450' well pump at 230v. If that's not enough let me know, I'll try to take some pictures.

    Thanks guys.
    Don
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #9
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    Re: Well Pump & Battery Array sizing

    I'm NOT the "well pump guy". but it seems to me your looking at a very high energy demand for a short period of time. You may find, if this must be run via solar, to run a smaller energy draw for a longer period of time more econimical. If you know what the actual water table is and the all the other pertanant facts you might be able to get by cheaper with a DC pump and battery, rather than a AC pump and inverter.

    Please note I have little experience, but understand you can have a 80-100 foot well, but artisian well in a few locations, so the depth of the well has little to do with the water table, so you may have a 450 foot well but a 50 foot water table, so you only need to lift a smaller distance. also important if considering something like this is the refresh rate, this depends on the water source, if yours is a permiable rock, it might have a slow refresh rate so you would need to have your pump at 80 feet with a 50 foot water table.

    Likely you would have a stand alone system if you choose to go this route...

    I'm well above my head here, but throwing out ideas, perhaps others with real world experience can give you some valuable information, this is more in the things to think about....
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #10
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    Re: Well Pump & Battery Array sizing

    I'm not sure what the regs are where you are but up here, the boondocks, every well is registered with the government and a 'log' of the well is registered....drill depth, well output, static level and sometimes quality. Contact a local driller and ask where (if) that information is recorded. That will get you started.

    If it was me I would get a larger cistern to pump into and only pump every 3 days, using a generator. If you want pressurized water you will need much smaller 12 v pump for delivery...

    hth
     
    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
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  • donquixo
    donquixo Registered Users Posts: 4
    #11
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    Re: Well Pump & Battery Array sizing
    westbranch wrote: »
    I'm not sure what the regs are where you are but up here, the boondocks, every well is registered with the government and a 'log' of the well is registered....drill depth, well output, static level and sometimes quality. Contact a local driller and ask where (if) that information is recorded. That will get you started.

    If it was me I would get a larger cistern to pump into and only pump every 3 days, using a generator. If you want pressurized water you will need much smaller 12 v pump for delivery...

    hth

    Thanks. Cistern would not be an option, only a discrete system with pressurized water (nothing bulky/extra outside). I've got a couple calls to the well guys in my area and will track down the logged information on this well.

    It seems, thinking about the long run and future power consumption of the house, the smaller 12V pump would be ideal.
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  • Gene.243
    Gene.243 Solar Expert Posts: 35 ✭✭
    #12
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    Re: Well Pump & Battery Array sizing

    As you get your numbers together you might want to look at these guys. http://www.solarpumps.com/
    Gene
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