Combining one source to multiple inverters

We have a large 80kW residential estate that has 5 separate electrical services which are to be fed with varying size PV systems.  There will be a central array will be located in a field remote from all 5 buildings.  Due to site constraints and util co. constraints we will be running very long DC lines to each building, where the inverters will be located, from the array field.  We have to do directional drilling and run on poles, so we would like to combine at the array and send one set of source conductors from the array to each of the buildings then 'uncombine' or split source evenly and feed multiple identical 240VAC SMA inverters.  Each building has a size different requirement, the largest being 30kW, then there's a 15kW, and a mix of other sizes.  Basically, I'm trying to find a way not to have to run multiple conductors over great distances.  Running AC to the array is out.  Getting 3 phase is out.    More details are I know, but you get the gist - my concern is that the mpp's will be at odds unless the inverters can be synched, but this is an area that we have not experienced before.  Any advice is welcome.

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 4,994 ✭✭✭✭
    Well, I'm lost are you in a grid tied situation with multiple meters? Trying to backfeed at multiple sites?

    Is this off grid and trying to charge multiple batteries from a single array. Basically it can't bee done effectively at the same time.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • mike95490mike95490 Solar Expert Posts: 8,370 ✭✭✭✭✭
    No MPPT controller (which is integral to PV GT inverter) can share an array with another MPPT.  The 2 will fight each other for control of the array and never acquire the peak power point.
    (Midnight Solar seems to think it could be done with steering diodes, but I think it's highly doubtful.)

    You really are better off to use a separate run from each array to it's own inverter. Using aluminum electrical cable is how the power company does it, and aluminum rated gear is common.
    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 ,

  • SunWindSunWind Registered Users Posts: 2
    Mike95490 that's exactly what I was concerned about, but I have a vague memory of attending an SMA training where they explained that they had the ability to sync multiple inverters (similar to stacking master/slave in offgrid).  Problem with multiple separate runs is that we have to directional bore and run on overhead lines ~1300ft so cost is insane because of conduit size limits for boring machine, plus labor for separate runs etc.  

    Photowit - this is grid tie with multiple smaller 240V inverters because no manuf makes single inv's large enough.
  • PhotowhitPhotowhit Solar Expert Posts: 4,994 ✭✭✭✭
    How big are you looking for? They make 50kw and 100kw and larger (I'm sure)

    Are you looking at the commercial/Utility inverters?

    Perhaps you are looking to separate to stay under a 10kw maximum?

    Curious, just how large an array are you talking about?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • jonrjonr Solar Expert Posts: 1,295 ✭✭✭✭
    edited November 2016 #6
    Sounds like a question for SMA.   Maybe if you start the inverters at different times (so that when they do MPPT determination is staggered).   And/or select different MPPT determination time intervals (so that overlaps would be rare).

    I am available for custom hardware/firmware development

  • mike95490mike95490 Solar Expert Posts: 8,370 ✭✭✭✭✭
    Maybe the SMA has a "sync cable" like the inverter generators or stackable inverters.  I don't own any SMA gear, so I've never looked into or heard of it.  Good Luck.
    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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