New Guy: latest system

Cariboocoot
Cariboocoot Banned Posts: 17,615 ✭✭✭
I'm glad I found this board; it's already answered some questions I needed to know about!

I'm 25km from the nearest power lines in the Cariboo, BC. I've had three off-grid systems so far (not including generators) and am about to upgrade to the fourth.

Currently I'm running 3 Sharp 175w panels in series to an MX60 (GREAT piece of equipment) charging two (there were four - don't ask) Trojan 6v deep cycles (& one Die Hard 160 - again, don't ask!) to power a 12v Xantrec XPower 3000 inverter. This set up runs an electric refrigerator (the only one on the lake), all the lights, and the computer/satellite hook-up (with VOIP phone). At full usage, this never exceeds 500 watts draw at any time. But now I need to be able to run two rather heavy AC induction motors for the water system, so I'm going with a full sine wave inverter.

I'll be adding another Sharp panel, but to keep the PV voltage below the MX 60's limit they'll now be wired 2 parallel banks of 2 in series. The extra low-light charging ability of a 72 volt array will be gone. I'm also going up to 24 volts, and an Outback VFX 3524 inverter. Thanks to this board I've been warned in advance about the AC input current problems, which is good because the only generator I've got capable of handling the default level is a miserable old gas-guzzling Coleman with a 10HP B&S. I'll re-programme the inverter so I can use the Honda 2000 instead.

I'm semi-retired now, but used to work for a division of Emerson Electric years ago. I do all my own engineering, and all my own cursing at salesmen who don't know what they're talking about. One thing I've discovered over the years: the factory specs on anything are a bunch of hooey.

My wife has already decided we need microwave, toaster, hair dryer ... So it looks like more panels in the future, and probably another VFX 3524!

A long ways from the 36vdc, 1000 watt Alpha Power with "sun" transformer! It was large, heavy, noisy ... and didn't work very well. Still have it too, 'cause it's too heavy to throw out!

Comments

  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: New Guy: latest system

    C-Coot, do you have a question you need assistance with? is it related to the pumps?

    Eric;)
     
    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
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: New Guy: latest system
    But now I need to be able to run two rather heavy AC induction motors for the water system, so I'm going with a full sine wave inverter.

    Do you have a power budget for them ? Cycle time ? Will they both kick in simultaneously?

    Induction motors have a pretty long spinup time (at least the ones I've seen took 5-6 seconds - I always thought the breakers would pop) and they also can generate power when shut down, be sure your switches can handle them.
    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 ,

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: New Guy: latest system

    I'm confident with the water pump (1/3 HP), but the digester pump is rated as 1 HP - 16A @ 125 VAC. Obviously that's running, so the start-up might be too much for the VFX 3524? I've tried it on my watt meter and get a 7 amp reading, so that can't be right! Maybe I'd better test it a couple more times and see if I get different results.

    There is the possability that both might start or at least run simultaneously. So for now there will be switches on them to prevent automatic function unless I know I've got the power available.

    Now if only it would stop raining long enough to get that other panel up on the roof. :)
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: New Guy: latest system

    It is very possible the average running power of your motor to be much less--depending on load at the time. Very generic applications will run at rated motor HP (something with a fixed load, like an aircompressor or fan will probably run closer to name plate vs a water pump/grinder depending on head, piping, volume, etc.).

    What some folks here have done is use there nice (and expensive) True Sine Wave inverter for their "home" appliances (such as the fridge/freezer) and electronics.

    And use the Modified Square/Sine Wave inverter (big and cheap) for the well/sump pumps which only run a few minutes per day (fridge/freezer is probably more likely to be damaged by using a MSW vs well pump--especially if it running well under nameplate rating)... For the sake of argument--assume that a motor running on a MSW inverter will draw 25% more power (because of the harmonics over fundamental line frequency which can only generate heat and no useful work). Fridge compressor is likely to run near nameplate vs your pump motor.

    Also, if you have problems with starting your induction motor (that uses a capacitor start circuit)--look into changing the starting cap to a larger one.

    These would allow you to have the ability to make good use of your TSW inverter and have the backup of the MSW inverter for running your big/intermittent loads until you can justify the costs/modifications of your setup/etc. with a TSW inverter.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: New Guy: latest system

    A deeper problem, is your battery bank. A couple <generic store brand> deep cycle batteries, even in parallel, will have difficulty starting that kind of a load.

    And with a Water pump, and sewage digester pump, you will eventually need both on, or else risk something nasty when you drain the bathtub, and are toweling off, and the sewage needs to start, but it's switched off !

    1HP is defined at 750W ( I think ) so allowing for losses, call it 850W running.
    At 120V, that's only 7A. So the 16A is likely the starting draw, and they cleverly spec it at 125V = 2,000 W for starting.

    At 12V, 2,000 = 166.67A Yikes. But that's likely very close to true starting surge, since run would be 800W ( 66A @ 12V )
    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 ,

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: New Guy: latest system

    Also, remember motors can run at 0.6 PF... So "amps" is also the Power/(V*PFC)

    7amps/0.6=12 amps...

    So, while the battery would only have to deliver ~750 watts at 7 amps (assuming 100% efficiency--which is never), the "real current" supplied by the inverter will have to be 1/0.6 times greater (VA=Volts*Amp rating).

    Sometimes, testing the loads against the inverter is the only way to know if a particular combination will work.

    But as Mike says--running large loads from a smallish 12 volt battery bank is not going to be very good either... Expensive to wire, hard on the batteries and lots of I^2 * R losses to boot.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: New Guy: latest system

    Neither motor works off the MSW inverter. I believe this is due to the wave signal giving the "appearence" of 25% less voltage than needed: not strong enough interference between the two magnetic fields to make it function. That is the main reason I'm going with the TSW unit.

    Also going with 24v to reduce the DC current. Batteries will be replaced, of course! Outback says you need at least 300 A/hrs to handle peak draws.

    Yes, 1 electrical HP is 746 watts, so drawing 7 amps @ 125 volts make sense: the "16 amp" plate rating must be start-up current. How odd! I've never seen such a sensible thing before. :)

    Thank you, everyone, for your input. Now if they'd just send the missing bits I might get this installed!
  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: New Guy: latest system
    Yes, 1 electrical HP is 746 watts, so drawing 7 amps @ 125 volts make sense: the "16 amp" plate rating must be start-up current. How odd! I've never seen such a sensible thing before. :)

    Typical AC motors are only ~50% efficient and the HP rating is the shaft power NOT the input power. Also, an inverter has deal with the power on surge which is listed as the locked-rotor spec which can easily be 5-7X the name-plate rating.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: New Guy: latest system

    Finally got it all up and running after an interminable delay caused by teh MATE not getting shipped!
    BOTH pump motors work fine, providing I don't leave them on 'automatic" which could cause them to run when there's no "extra power" available. The only trouble is having to re-programme the inverter to not overwhelm the generator: it's only capable of 13 amps max out. It's manageable!
    So it's now 4 175 watt Sharp panels, Outback MX 60, 320 Ahrs of 24v batteries, and the VFX 3524 inverter. And it works fine. :)
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: New Guy: latest system

    Do a search on this site,,, If memory serves, there is a thread about effluent pumps. I have a memory of people using much smaller, even 12vdc pumps with longer run times instead of larger pump for shorter times. Same with water pumping. Are you pumping directly out of the lake, or from a deep well?

    I use a shurflo submersible (24vdc) and draw out of the lake, and it works great. Draws 7 amps at 12vdc, and runs ~15-30 minutes per day. (We have no flush toilets, and we do laundry from a different water source.

    Another option would be to size your holding tank to allow you to run the effluent pump(s) off a genny for a few minutes a day.


    Tony

    PS We live with no micro, no electric toaster, and our fridge is Propane. That keeps our array size small an our battery life good. We use the genny for the power tools.