3 phase off grid system?

Hi there,
I had an inquiry from a guy that wants an off grid system to provide 3 phase power. Currently he is running his whole off grid operation off a 125kW Genset that is 480 Volt line to line and 277 volt Line to neutral. The Gen is currently powering up several houses, butcher shop, and all the out-buildings.
I realize I need to gather more info and will do so when we visit the site, however just trying to do as much back-round research as possible before hand. If we get this job, will be an interesting project, potentially large scale.
My first thought is to keep the Gen for back up and to run his HUGE loads when needed, but have an off grid system to power all the other daily loads as required......(that may not even require the system to be 3 phase but just stack as many inverters as necessary.........)
Thanks for any dialogue on the topic.


  • BB.BB. Super Moderators, Administrators Posts: 33,080 admin
    The 277 VAC line to neutral on a 480 VAC system is generally used for lighting of shops/warehouses/large offices. There is not much in the way of other equipment that runs from 277 VAC (that I am aware of). And many of the newer 277 VAC lights can run off of other voltages (as low as 120 VAC). Obviously, the lower line voltage, the higher the current draw (P=V*I), and you may need more branch circuits for the conversion.

    For this large of system--You probably need a Power/Electrical Engineer to work with you/the customer. Many pieces of equipment can be wired to run on 480 or 208/240 VAC three phase (but not all).

    It sounds like the butcher shop may be the only thing running 3 phase power (the refrigeration compressor). The rest of the housing is probably running 240/120 VAC split phase (around Burnaby Canada?). Either the genset has step down transformers, or there are some spaced around the property.

    Going back and identifying loads--Looking for conservation opportunities, etc.--Should be a big part of the process... For folks that have never done any conservation before, reducing energy usage by 50% can be obtained (insulation, new/energy efficient compressors/refrigeration/heat pumps/LED Lighting/etc.).

    What does the sunlight look like (good sun exposure or trees/deep in valley/marine layer/etc.)?

    Average Solar Insolation figures

    Measured in kWh/m2/day onto a horizontal surface:


    From October through February--Not a lot of sun.

    If the large energy usage is seasonal (freezing fish/game/cattle) for a relatively short period of the year (or deep winter), a Genset may still be the most cost effective for short/peak periods of energy usage. And use Solar for base loads (homes, outbuilding lighting, etc.).

    Good Luck,
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Just because he has a 125kw genset, does not mean he NEEDS 125kw.    He likely only needs, say, 75kw, but got a good deal on a larger genset.
    Finding out what the loads are, is crucial .   refrigeration, meat saw for cutting frozen meat.
     Moving heating loads to gas could be huge, getting 2 houses off of electric stoves, and electric water heaters, baseboard heating....

    Trying to rewire an existing compound from 3ph, to split phase, would be real messy, spend the $ for 3ph stackable inverters.   But gotta find out the actual load requirement.
    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 ,

  • Dave AngeliniDave Angelini Solar Expert Posts: 6,387 ✭✭✭✭✭
    Schneider Electric Solar is in Burnaby. I know a few Engineers there who have done similar, many times. You are right ! You need alot more data! 
    Look at the wiring of the compound and where the power center will be located. You would be lucky if it was in the middle of the chain.
    "we go where power lines don't" Sierra Nevada mountain area
    E-mail [email protected]

  • ligwydligwyd Registered Users Posts: 193 ✭✭
    So, prior to a site visit that will be happening in the next week or so, is it the consensus that "ALL" top shelf off grid battery based systems in a 3 phase configuration (3 inverters) will be 120V-208V being 120V line to neutral and 208V line to line???
    Then anything after that would be step up or down transformers???
    First of course, given that all HUGE loads, be run off an appropriately sized genset, as that would still be the most economical way of running those big loads.....
  • ligwydligwyd Registered Users Posts: 193 ✭✭
    Also. what are the options for a battery based 3 phase off grid system?
  • BB.BB. Super Moderators, Administrators Posts: 33,080 admin
    As far as I know, you have the choice of 3 separate battery banks to the 3 separate inverters... Or you can have one large bank and connect all batteries together... I suggest the one bank is going to be easier to manage--All energy stored in one place, vs 3 separate storage banks and trying to balance the 3 separate inverters (on smaller 3 phase installations, typically you have one phase that power most of the building--120/240 VAC, and the other two phases are only needed for specific 3 phase equipment (unless you go to a lot of trouble balancing the three sets of loads on the three inverters).

    Depending on what are the three phase loads--There are ways of using single phase power to run three phase equipment (capacitor start, large 3 phase idler motor--sort of like a motor/generator set, VFD (variable frequency drives), etc.).

    And you have the choices of flooded cell lead acid, AGM or other sealed batteries, and lastly the LiFePO4 type (not including the others such as Nickel Iron "Edison" type batteries, etc.).

    Without knowing more about the installation, it is probably not worth even guessing at this time.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ligwydligwyd Registered Users Posts: 193 ✭✭
    Yes, I need lots more info.............
    If the Genset read out is correct the operation is using 1554kWh's per day!!!
    Never done a system this big. Will have to look at options for micro grid/ diesel hybrid etc..... Maybe even large scale wind turbine.
    You guys know who the go-to engineering firm would be for large scale off grid micro grid design?
    I'll be all over the phone tomorrow:)
    One step at a time...
  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited October 2020 #9
    There are many options for 3 phase inverters here is a random search result,  https://www.alibaba.com/product-detail/3-Phase-Off-Grid-Solar-Inverter_1600101347266.html?spm=a2700.galleryofferlist.topad_creative.d_image.847db1f596Vwr4
    This is an EU version there are split phase examples as well, using 3 separate units can be done but my opinion it'would be easier with a single device.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • BB.BB. Super Moderators, Administrators Posts: 33,080 admin
    edited November 2020 #10
    A large home with 3 phase generator and several Victron inverters + battery charger on 3 phase in Netherlands--Wrong engineer left a system that was not working correctly:


    Not saying this will happen with this project--But getting a competent power engineer at the beginning is going to be a big help.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,387 ✭✭✭✭✭
    Big Systems can have Big problems. Searching on the Internet is not really fair to your possible client. You need to have experience or get a Pro as Bill has said. I would walk on this one. I do know several folks up that way. It is the land of Diesel and solar in summer.

    "we go where power lines don't" Sierra Nevada mountain area
    E-mail [email protected]

  • ligwydligwyd Registered Users Posts: 193 ✭✭
    Turns out the customer only wants a 3 phase system to power up critical loads when the main gen-set is down. Loads are: well pump, fridge/ freezer in the butcher shop and lights. After doing load analysis over a period of I'll know what size of system will be needed. Still unsure as to the most reliable 3 phase battery based off grid equip? XW's, SMA?........Have to keep digging.....
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,387 ✭✭✭✭✭
    It really is how easy it would be to support the equipment. Hopefully you will not need to size for clusters. Clusters can be a nice thing also as you have spares on site and if a battery fails you have time. Lot's more to learn on that one alone.

     I am partial to XW because I have designed and used them since the start. Really everything out there in the world is based on what XW did and continues to do. You are in the land (Burnaby) of XW and support is driveable.

     I would use one of Schneiders design engineers as that will go a long way if there are problems down the road. There probably won't be either.
    "we go where power lines don't" Sierra Nevada mountain area
    E-mail [email protected]

  • ligwydligwyd Registered Users Posts: 193 ✭✭
    Hey Dave, can you define clusters?  Rather here it from you than google..... :)  Also any feedback on using 3 outback inverters for 3 phase? vs XW's
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,387 ✭✭✭✭✭
    "we go where power lines don't" Sierra Nevada mountain area
    E-mail [email protected]

  • ligwydligwyd Registered Users Posts: 193 ✭✭
    Got it. Thanks Dave. I'll read up. Also gonna call Schneider direct to discuss engineering a system.
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