Narrowing my deep well pumping options

DSinOR
DSinOR Registered Users Posts: 18 ✭
in Solar Water Pumping #1
I've started a solar emergency power system: 580watts of PV, 24v system voltage, TS-60 CC, and four 6v costco golf cart batteries. Eventually I hope to expand to 1160watts of PV and eight batteries. Presently I have 3 small 12v MSW inverters collected over the last few years, 500 and 700watt models. I haven't yet bought a big 24v PSW inverter.

I plan to replace the pump in my 300' well. In this August drought, I found static water level at 135', 4-hour draw-down level of 141'. My 55psi pressure tank = 126'. I intend to hang the pump at 175' + 126' of pressure tank = 300' of head.

My present pump is 240v 1HP, age unknown, likely 38 years old. My galvy tank is 45gallon hydro-pneumatic with AVC, check valve and down-well bleedoff. The tank system works great, so I plan to keep it for now.

Options I've read about on this board:
Grundfos SQFlex - $1868 delivered.

Grundfos 15SQ10-220 - $603 delivered + Samlex PST-200S-24 = $679 delivered + an autotransformer for an estimated $200 for a total of $1482.

VFD ($175 estimated) + 3-phase 230v Franklin pump ($600 estimated) + Samlex 2000w inverter for $679. I'm not attracted to this option because the cost is the same as the 15SQ, but the pump is 3-phase and I'd prolly need a spare backup VFD,otherwise I'd have no way to run the pump if VFD#1 failed.

The Flex option costs $400 more than the 15SQ option, and at the end of the day, I don't own a nice fat 24v 2000watt inverter that could satisfy other needs around the place.

So I'm leaning towards the 15SQ option.

Questions:
Can someone school me on the autotransformer thingy? Can I use a 2000watt psw inverter to power an autotransformer to operate a 1700watt-at-full-load soft-start well pump? I haven't seen a formula for choosing an autotransformer. I'm assuming that volts get doubled, amps get halved, and watts travel through relatively unscathed. It that how it works?

What rated autotransformer would I need? Reliable brand names? Vendors with good prices?

Thanks!

PS - Remember, this is all part of an emergency backup plan. In emergencies, I plan to run the well 3 minutes or less per day, plus run a compuer for a few minutes, plus blow a kiss to a 145watt freezer, plus charge a few batteries.
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Comments

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Re: Narrowing my deep well pumping options
    DSinOR wrote: »
    PS - Remember, this is all part of an emergency backup plan. In emergencies, I plan to run the well 3 minutes or less per day, plus run a compuer for a few minutes, plus blow a kiss to a 145watt freezer, plus charge a few batteries.

    If your emergencies are not often, I think you would be better off with an efficient inverter type generator. A honda or yamaha could do the job for less than $1000. You would still need the autotransformer if you need 240 volts.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Narrowing my deep well pumping options

    Autotransformer: http://www.solar-electric.com/x-240.html $312 Capable of 4kVA

    Or you could buy a Magnum 24 VDC / 240 VAC inverter: http://www.solar-electric.com/maenms4040wa1.html $2,200

    It all just gets more and more expensive, doesn't it? :roll:

    I like vtMaps suggestion but I'd go with an El Cheapo gen that has 240 VAC output to begin with if these are occasional, short outages.

    A couple of observations: Don't replace the pump until you need to. Samlex inverters are not the best choice for this sort of application.
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  • DSinOR
    DSinOR Registered Users Posts: 18 ✭
    #4
    Re: Narrowing my deep well pumping options

    I've already got panels, batteries, and CC.

    My present decision point is which pump and related equipment so that I can use the solar to run the well a few minutes if needed. Thanks!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Narrowing my deep well pumping options

    So you have your heart set on that Samlex 2kW inverter and want to know which pump is the best choice for it?
    For a conventional deep-well pump I would say "none" because I'd expect that inverter to have a stroke trying to start it even with a VFD.

    The 16SQF-10 can run from AC or DC (within range). The AC does not have to be 240 so you would not need a transformer or 240 Volt inverter. It can run directly off panels if you have enough panels and the linear current booster. The range of power options makes it much more likely you could get this to work. You could go for a 48 VDC system and run directly from DC and only use the inverter as-needed, et cetera.

    The down side: they are very dependable, but if it does break down you can't replace it from the local plumbing shop in town. This is the only advantage to a conventional pump.
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  • DSinOR
    DSinOR Registered Users Posts: 18 ✭
    #6
    Re: Narrowing my deep well pumping options

    Thanks coot! FWIW, our two replies above were simultaneous.

    The 15SQ soft-start pump has a full-load draw of 7.4amps at 230v, which is 1702 watts. To my understanding, there is no start-up spike, it just eases up to the load.

    Assuming there is no other load on the line, why would the the Samlex SA-2000K-124 inverter struggle to meet this demand?

    Thanks, I'm learning.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Narrowing my deep well pumping options
    DSinOR wrote: »
    Thanks coot! FWIW, our two replies above were simultaneous.

    The 15SQ soft-start pump has a full-load draw of 7.4amps at 230v, which is 1702 watts. To my understanding, there is no start-up spike, it just eases up to the load.

    Assuming there is no other load on the line, why would the the Samlex SA-2000K-124 inverter struggle to meet this demand?

    Thanks, I'm learning.

    I'm trying to point out that the Samlex would have a hard time with a conventional pump. The SQ is all soft-start built it: 90 to 240 VAC, 400 to 1400 Watts. If the power is low it simply runs slower. You get less flow/lift/pressure (you have to trade of something) but it still runs. If you have the power you get maximum pump performance. It would run at 120 VAC and draw around 15 Amps which would almost max out the Samlex.

    There's the only drawback; if you need to run the pump at the same time as something else the inverter could be overloaded.

    You will need some additional equipment to get the system wired up: it is not just power to the pump. Your best bet is to discuss the install with someone who is familiar with the various installation options like the people at NAWS. You tell them what you're trying to do and they can tell you what all you need to get it to work.

    You might first want to read through the SQ product guide: http://lib.store.yahoo.net/lib/wind-sun/L-SP-TL-014.pdf
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  • DSinOR
    DSinOR Registered Users Posts: 18 ✭
    #8
    Re: Narrowing my deep well pumping options

    Coot - You are referring to the SQFlex series that run on a wide range of either AC or DC voltage.

    I am referring to the Grundfos SQ series, a totally different pump that runs only on "115v" or "230v" AC, depending on the model. It is a soft start pump. The model I'm considering is 15SQ10-220, which is a 230v model. It draws 7.4amps at full load, and unless something goes wrong, it never draws more than 7.4 amps, even at start-up.

    Okay then. It seems like I should be able to run this pump for a few minutes during emergencies with a $700 Samlex SA-2000K-124 (2000watt 24v) inverter connected to an autotransformer. That's what I'm asking.

    Here are my questions:
    1 - Can I run the Outback X240 autotransformer from a single inverter?
    2 - If this inverter is rated for 2000w with 4000w surge, and I connect it to the X240 autotransformer, why would it not run my 1700watt well pump that has no start-up surge?
    3 - What are the losses associated with connecting a 2000w inverter through an autotransformer? Will I still have most of the 2000watts on the other side of the autotransformer?
    4 - Noob question:
    The Samlex transformer I'm looking at is rated for 2000watt continuous output. It has two standard AC NEMA5-20 GFCI receptacles on the face. Can I get the full 2000w from just one of the receptacles, or is teh outpu rating split between the two receptacles? This inverter also gives access to an internal hardwiring output voltage terminal block. Can I get the full 2000 watts from the internal block? I've read the entire product manual, but cannot find this info.
    5 - I was under the impression from reading threads here that the Samlex PSW inverter is apretty good unit. Is that not the case?

    Thanks!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Narrowing my deep well pumping options
    DSinOR wrote: »
    Coot - You are referring to the SQFlex series that run on a wide range of either AC or DC voltage.

    I am referring to the Grundfos SQ series, a totally different pump that runs only on "115v" or "230v" AC, depending on the model. It is a soft start pump. The model I'm considering is 15SQ10-220, which is a 230v model. It draws 7.4amps at full load, and unless something goes wrong, it never draws more than 7.4 amps, even at start-up.

    Yeah, here's me reading an 'F' into the model 'cause it's what we normally deal with. Sometimes "auto-meaning-editing" is as bad as "auto-spell-correct". :p
    Okay then. It seems like I should be able to run this pump for a few minutes during emergencies with a $700 Samlex SA-2000K-124 (2000watt 24v) inverter connected to an autotransformer. That's what I'm asking.

    Here are my questions:
    1 - Can I run the Outback X240 autotransformer from a single inverter?
    2 - If this inverter is rated for 2000w with 4000w surge, and I connect it to the X240 autotransformer, why would it not run my 1700watt well pump that has no start-up surge?
    3 - What are the losses associated with connecting a 2000w inverter through an autotransformer? Will I still have most of the 2000watts on the other side of the autotransformer?
    4 - Noob question:
    The Samlex transformer I'm looking at is rated for 2000watt continuous output. It has two standard AC NEMA5-20 GFCI receptacles on the face. Can I get the full 2000w from just one of the receptacles, or is teh outpu rating split between the two receptacles? This inverter also gives access to an internal hardwiring output voltage terminal block. Can I get the full 2000 watts from the internal block? I've read the entire product manual, but cannot find this info.
    5 - I was under the impression from reading threads here that the Samlex PSW inverter is apretty good unit. Is that not the case?

    Thanks!

    1 - Yes. But remember that a Watt is a Watt. 7.4 Amps on 240 VAC is 1776 Watts, but 1776 Watts on 120 VAC is 14.8 Amps. This is pretty near "trip point" for a standard AC outlet and you would be running a 2kW inverter at 90% capacity. Fortunately this is peak power for the pump. But it brings up the question of adding/removing/controlling other loads.
    2 - See above. Samlex surge ratings are somewhat 'fleeting' in nature. These bigger units are new and should have better output, but I haven't heard any reports from the real world yet. They also have pretty big self-consumption; something like 36 Watts.
    3 - This is the unit you are looking at: http://www.solar-electric.com/sa2wa24vosiw.html As far as I know the outlet is a standard duplex design: 20 Amps on either plug or 10 each if both are used. Since it is GFCI you will probably want to remove it and hardwire the inverter (it is designed for that). Ground-fault is not that desirable here. The power loss of the autotransformer should be minimal - maybe 3%. The worst part is that the pump switching will be on the 240 VAC side, so the transformer will consume a small amount of power all the time the inverter is active. You can set these inverters to "standby" mode which should be able to exclude the draw of the transformer. But any load that "wakes" the inverter will activate that parasitic load.
    5 - Samlex units are fine for what they are for. The small, stand-alone ones are a poor choice for motors because they essentially have no surge rating at all (1 sec). Like I said, I haven't heard how well these new units perform in the field. Maybe someone else has theirs running now?
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  • DSinOR
    DSinOR Registered Users Posts: 18 ✭
    #10
    Re: Narrowing my deep well pumping options

    Thanks Coot! That clears up a lot for me.

    FYI - I read somewhere that the transformer will stay off line when not in use if you wire the pump control to the primary side. I'm no expert on this, but will be looking to learn more about it.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #11
    Re: Narrowing my deep well pumping options
    DSinOR wrote: »
    Thanks Coot! That clears up a lot for me.

    FYI - I read somewhere that the transformer will stay off line when not in use if you wire the pump control to the primary side. I'm no expert on this, but will be looking to learn more about it.

    Yes, if it is practical to do that. It would depend on how the wiring is laid out, distances and such. And also if the switch can handle the higher current on 120 VAC (usually they can).
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  • Texas Wellman
    Texas Wellman Solar Expert Posts: 153 ✭✭
    #12
    Re: Narrowing my deep well pumping options

    Keep us updated on how this works out for you.
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