UPS modified inverter charger and solar panels

System
System Posts: 2,511 admin
in General Solar Power Topics #1
can any modified sine wave UPS inverter charger be linked with solar panels to charge the same battery bank without damage to the system?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: UPS modified inverter charger and solar panels

    Never say never, never say always.

    We can give you a better answer with more specifics,

    Tony
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: UPS modified inverter charger and solar panels
    icarus wrote: »
    Never say never, never say always.

    We can give you a better answer with more specifics,

    Tony

    My inverter is a UPS 3000watts inverter with a built in 10 amps charger(made in Taiwan sold by Ki-point on the internet). I am thinking of joining this in parallel to 128 watts array of solar panels.
    Thanks
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Re: UPS modified inverter charger and solar panels

    I may be a bit thick today, if so sorry all.

    I assume that the ups has a battery? You are currently charging that from the inverter/charger? Now you want to feed 12vdc into the inverter directly,from the panel, or are you going to feed the battery and then feed the inverter?

    The latter scenario makes sense. Charge the ups with a panel, (with a charge controller), then run the ups from the battery.

    If I am wrong about what you are doing, please advice,

    Tony
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,658 admin
    #5
    Re: UPS modified inverter charger and solar panels

    Generally, to have any useful recharging/operational capacity from your solar panels connected to the Inverter's battery--you need a charge controller to properly control the current/voltage to the battery.

    And, if you are taking a randomly configured UPS inverter (mod sine possibly)--you don't really now how the input battery is configured... Are the leads floating or is one side grounded.

    With normal 120 VAC lines in a home/business in the US--the Neutral wire is actually grounded (per NEC)--and assumed to be grounded by many applications.

    With a mod sine inverter, generally you cannot ground reference one its 120 VAC outputs and ground reference the battery bank. For safe DC solar and proper operation of many solar charge controllers--they pretty much assume one side of the battery (generally the negative) is grounded.

    You may get everything to run without battery grounding--but be really careful that you don't end up with energized charge controller sheet metal or assume that you are only dealing with 12 volts and ground on the battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: UPS modified inverter charger and solar panels

    Thanks for all the useful inputs so far.
    The inverter charger has no battery of its own. It needs to be connected to a battery but is said to have an automatic transfer system when the AC power goes off, i guess that's why they call it a UPS. So, I was wondering if I could add in addition to the inverter charger cable, the solar panel cables in parallel to increase the charging power. The inverter charger has a 10 amps charger built in and the solar array is about 128 watts.
    I am a starter/novice and I hope to charge a battery bank of 800ah.
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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: UPS modified inverter charger and solar panels
    showby wrote: »
    Thanks for all the useful inputs so far.
    The inverter charger has no battery of its own. It needs to be connected to a battery but is said to have an automatic transfer system when the AC power goes off, i guess that's why they call it a UPS. So, I was wondering if I could add in addition to the inverter charger cable, the solar panel cables in parallel to increase the charging power. The inverter charger has a 10 amps charger built in and the solar array is about 128 watts.
    I am a starter/novice and I hope to charge a battery bank of 800ah.

    It's good to be able to ask people that know. good forum.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    Re: UPS modified inverter charger and solar panels
    showby wrote: »
    The inverter charger has a 10 amps charger built in and the solar array is about 128 watts.
    I am a starter/novice and I hope to charge a battery bank of 800ah.

    128W of solar array will actually deliver about 100W, if precisely aimed. That's not going to be much of a charge assist to your battery bank (about 6 amps, for 5 hours on a good day, about 30 amp hours @ 15 v)
    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

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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #9
    Re: UPS modified inverter charger and solar panels

    If all you are doing is trying to keep the ups battery charge for emergency use, it sounds like you are pretty close with you panel. On the other hand, if you intend to draw down the ups and then recharge it from the panel, it would be way undersized for regular use.

    Tony
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #10
    Re: UPS modified inverter charger and solar panels

    an ups or any inverter is pretty much useless without a battery so you should buy at least one. now a 3kw inverter will draw heavilly from a battery unless you self limit. in assuming it is designed for a 12v battery, 3000w/12v=250 amps being drawn if in continuous full power use. more input may be needed from you on what it is in watts you intend to draw and for how long each day.
    as it is in your current charge sources available the minimum would be from pvs at about 6a (with a good controller and bts). this has with the standard 5-13% charge rates battery ah capacities of 120ah-46ah. solar isn't your only charge source as you also have the 10a built-in charger that singly could go with battery ah capacities of 200ah-77ah. combining these 2 charge sources gives a total charge of 16a and the battery capacity ranges suitable are 320ah-123ah. it is obvious with what is here that drawing for full inverter capacity would kill a battery bank even at 320ah. also note that you don't want to drain a battery beyond 50% without sacrificing too much battery lifespan so the max to be drawn ability would be 160ah (on 320ah battery bank) with your present charge sources. you could spread that out over for example 8hrs which would allow 20ah for each hour x 12v or 240watts of ac.
    also be carefull what that modsine inverter is connected to as items with electric motors draw much more power from it with the ability to shorten the life of said motors and even some wall chargers can blow. having a 3kw modsine inverter is a waste to me as i'd want sinewave to run big motors and such, which includes refrigerators.
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  • System2
    System2 Posts: 6,290 admin
    #11
    Re: UPS modified inverter charger and solar panels

    Thanks a lot.
    I actually plan to us a battery bank of 3 at 200ah =600ah but i now realise having read your input that my charging options will not be adequate for this.
    I also have an automatic ctek multi charger ZS 25000 but don't know if this could be connected to a modsine inverter, hence the dillema as I am a novice in this field.
    cheers
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  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    #12
    Re: UPS modified inverter charger and solar panels

    Are you sure the UPS is 12v? I have seen quite a few larger UPS's that are rack mount and run on all sorts of voltages, I even saw one that had a 96v bank. It was neat because the battery wires were 12 gauge.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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  • System2
    System2 Posts: 6,290 admin
    #13
    Re: UPS modified inverter charger and solar panels

    Yes the ups is definitely 12 volts - a 3000 watts inverter charger with built in 10amps charger.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #14
    Re: UPS modified inverter charger and solar panels

    having another charger can put the current back into the battery bank, but try to size everything if you can. be cautious in putting battery chargers on batteries as many of these chargers are not regulated and can damage your batteries if allowed to go beyond the bulk stage voltage limit that sets up the absorb and/or float stage to initiate on multistage chargers. that means you baby sit it while it charges without regulation.
    you may wish to read in this forum to gain a better idea of what you wish to do and how to go about it.
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