Multiple Inverters on same grid ?

rtribble
rtribble Solar Expert Posts: 28 ✭
in Off Grid Solar & Battery Systems #1
I have some a problem that needs some think time:

1. I have an off grid setup with two onsite grids
2. each grid has a pair of trace 5548's setup for 230v
3. all the solar panels/batteries and electronica are in a building at one corner of the 40 acres, near my house
4. I have a 300 ft drop for a stream with at least 60gpm flow
5. the problem is that is 1400 feet away from the batteries
6. I have a 230V 6 gauge line covering most of that distance.

So If I put a Harris hydro in at the bottom of the hill, it should do ~1300 watts 24/7, but DC

Can I invert on location and connect up to the 230V ac line near it ? How ??
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Multiple Inverters on same grid ?

    What you're looking at would be AC coupling.

    The hydro turbine would drive a GT inverter like a Windy Boy whose AC output would connect to the exist AC output from the SW's. (Check: 230 VAC? NA standard would be 240 VAC @ 60 Hz.)

    Trouble is, the SW's aren't meant to be AC coupled like that. A Sunny Island would. But how much do you want to invest to get it to work? Might be easier to put a battery bank at the turbine site, inverter with a standard OGI, run 240 VAC up to the main site on its own wires, then use that to keep batteries charged.

    I don't see any simple, inexpensive solution here.
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  • mtdoc
    mtdoc Solar Expert Posts: 600 ✭✭
    #3
    Re: Multiple Inverters on same grid ?

    How about using a Powerspout ME 250 instead of the Harris Hydro?

    At 250 volts, 5 amps, 1400 feet wire run of 6AWG will give you about a 2.5% voltage drop.
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  • rtribble
    rtribble Solar Expert Posts: 28 ✭
    #4
    Re: Multiple Inverters on same grid ?

    explain the SW problem ? and what is "standard OGI" ?

    voltage on grid is 240V 60hz.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Multiple Inverters on same grid ?

    "OGI" = Off Grid Inverter (as opposed to a GTI = Grid Tie Inverter). Standard meaning "typical": one that is designed for off grid use and does not have AC coupling abilities such as the Sunny Island or Xantrex XW (aka hybrid inverters).

    The SW is a venerable design, but it was never meant to have AC fed to its output the way AC coupling works. AC on the AC in is different. But that doesn't work when you're trying to use a GTI as the source because it needs the AC signal from the battery-based inverter to sync to. Then it needs that inverter to be able to regulate the power available from the GTI.
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  • rtribble
    rtribble Solar Expert Posts: 28 ✭
    #6
    Re: Multiple Inverters on same grid ?

    I understand that the micro inverters can do 240AC, do they play well with SW5548's ?could i use a micro inverter type to convert the hydro output to my local line at
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Multiple Inverters on same grid ?
    rtribble wrote: »
    I understand that the micro inverters can do 240AC, do they play well with SW5548's ?could i use a micro inverter type to convert the hydro output to my local line at

    It isn't the GTI that causes the problem; it's that the SW's aren't designed to have that AC input connected to them. They won't be able to regulate it, so any power not used by loads will back-feed and charge the batteries without any regulation. This sometimes works with PV power GTI's because the load demand during daylight can be high enough to negate their output. But in this case you're looking at 24 hour hydro power (which needs a load or mechanical regulation to keep from overspeeding the turbine) so there would be a constant effort to charge batteries even when they don't need it.

    That's assuming the SW's will function that way at all and not just go up in smoke.
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  • rtribble
    rtribble Solar Expert Posts: 28 ✭
    #8
    Re: Multiple Inverters on same grid ?

    Thanks for all the education, here is where I am now !

    at the hydro end:
    1. hydro to batteries, 48V with dump control, to regulate the output
    2. some type of inverter, to 240V ac
    3. run wire (15 amps capacity) 1400 feet to battery house (1400/240 =~ 6 amps)
    4. into 240V marine battery chargers (with voltage regulation) to the main battery bank
    5. main battery will also have dump control to water heater/pump for fountain
    6. main battery bank supplies power to 4 sw5548's paired up to 240V ac for the2 house circuits
    7. net is:
    12000 watts solar daytime
    1200 watts (line loss) 24x7 10 months out of the year
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Multiple Inverters on same grid ?

    Thinking out loud here.

    Pretty sure the SW's have chargers built-in. You might be able to use the 240 VAC from your hydro-inverter set-up to power them directly (as generator input). Then if the SW's can do gen support (think so) the hydro would supply most of the power and when the loads exceed its ability the SW's would pick up from the main battery bank.

    I do not see a reason for a dump control on the main battery bank. If you want to more fully utilize the panel power when batteries are full, you can set up a circuit to switch on more load (such as water heater) when battery Voltage is high.
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