Need help with 3-phase solar system

agibbstxagibbstx Registered Users Posts: 3
I am building a new shop building for my plumbing company on a 60 acre area out in the boonies in hurricane country. At our current place, we were without grid power after the last hurricane for 5 weeks. I am thinking a 20kW solar system can offset some of our power usage. Our grid power and some of our equipment is 3-phase 480/277Y.

I have been doing some research for the last few months and I haven't decided on a panel brand yet, but I think I want the SolarEdge 20kW 3-phase grid tie inverter. I also want to put in something similar to the SunnyIsland battery system, but from what I can tell the SunnyIsland won't work with my 277v l-n power. The final power source I want to tie in is a 30kW three phase generator.

Also, while most of my 3-phase equipment has VFDs installed so little surge issues. The big monkey in the room will be the 20-ton scroll chiller. While I can demand limit it when running off-grid, the compressors pull 15 amps, but the LRA is 130.

If y'all have any ideas, I'll be grateful.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need help with 3-phase solar system

    Welcome to the forum.

    I'd suggest a generator for the big stuff and solar to run the little stuff. Why? Because putting in a full-size solar power system to run the big stuff will be a lot of money spent for relatively little return.

    Let's start with your Solar Edge grid-tie inverter. When the power goes down it will produce nothing: no grid, no power. So that's not going to be very helpful.

    There are inverters that can be stacked for 3 phase AC, and I believe SMA actually makes some. I know Outback does. But here's the thing: run the numbers on the amount of inverter, battery bank, and PV + charge controller necessary to supply those power demands even momentarily, and then look at it in terms of Watt hours as well. It will be a lot of money; only you can decide if it is worth it.

    Before you go any further with any plan you will need numbers for maximum Watts (Volt Amps) and total Watt hours for a given day. That's not easy to measure for a workshop as you never know exactly what equipment will be needed on any given day.
  • DanS26DanS26 Solar Expert Posts: 241 ✭✭✭
    Re: Need help with 3-phase solar system

    Investigate installing a soft start on the big chiller....could possibly reduce that 160 amp LRA by 40%. Thus a much smaller generator could be sized for your emergency application.

    Check out this three phase soft starter:

    http://www.hypereng.com/three_phase.html
    18.2kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring with PVOutput.org
  • AuricTechAuricTech Solar Expert Posts: 140 ✭✭
    Re: Need help with 3-phase solar system

    Building off of Cariboocoot's response, I suggest that you start with a mission statement (exactly what you intend to achieve) that states the parameters of your planned PV system. Given what you've already posted, your mission statement might read something along these lines:

    I need to design a grid-tie hybrid PV system (I'm using this term to describe a photovoltaic system that normally interacts with the power grid, but includes a battery bank and other components to allow the system to function off-grid if needed) that can support x kilowatt-hours of power use daily while off-grid. Ideally, my system should support y Watts of "3-phase 480/277Y" power, and should be able to integrate power from a 30kW three phase generator. I am willing to spend $z on this system.

    Once you've defined the parameters of your desired PV system, it becomes much easier to advise you on how best to design a system that meets those parameters (or how best to redefine your parameters within your budget and true needs).
  • agibbstxagibbstx Registered Users Posts: 3
    Re: Need help with 3-phase solar system
    AuricTech wrote: »
    Building off of Cariboocoot's response, I suggest that you start with a mission statement (exactly what you intend to achieve) that states the parameters of your planned PV system. Given what you've already posted, your mission statement might read something along these lines:

    I need to design a grid-tie hybrid PV system (I'm using this term to describe a photovoltaic system that normally interacts with the power grid, but includes a battery bank and other components to allow the system to function off-grid if needed) that can support x kilowatt-hours of power use daily while off-grid. Ideally, my system should support y Watts of "3-phase 480/277Y" power, and should be able to integrate power from a 30kW three phase generator. I am willing to spend $z on this system.

    Once you've defined the parameters of your desired PV system, it becomes much easier to advise you on how best to design a system that meets those parameters (or how best to redefine your parameters within your budget and true needs).

    Since you were nice enough to post that, I'm gonna steal it from you. :P

    I need to design a grid-tie hybrid PV system (I'm using this term to describe a photovoltaic system that normally interacts with the power grid, but includes a battery bank and other components to allow the system to function off-grid if needed) that can support 40 kilowatt-hours of power use daily while off-grid. Ideally, my system should support 20kW of "3-phase 480/277Y" power, and should be able to integrate power from a 30kW three phase generator to cut in should the power outage last. I am willing to spend $50,000 on this system, not counting the generator.

    That said, in response to the earlier messages, I was under the impression that adding the SunnyIsland inverters along with a transfer switch would allow the sunny island / generator to activate the grid connect side of the primary inverter and allow it to continue to deliver solar power. If I'm wrong, let me know. I design building automation systems for a living, but all these solar options are driving me up a wall.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need help with 3-phase solar system

    I don't think this going to happen.

    40 kW hours per day would indicate > 10 kW of array over 4 hours of equivalent good sun.

    20 kW of power at the moment would indicate very large inverter and battery bank to supply that much power. Around 400+ Amps @ 48 Volts; 4,000 Amp hour battery bank.

    $50,000 budget is limiting as the cost of the array and battery bank will consume a significant portion of that (as per above).

    A Sunny Island can be used as a sync source for a GT inverter, but not for 20kW worth as the SI is only 5kW; it would not be able to manage 4X that much power nor a 3 phase system. You would be better off with a hybrid system which has the GT connection integral with the battery back-up. What that would be exactly I don't know and a rough estimate (based on using 8kW Radian inverters) would be $24,000 just for the inverters. Probably $15,000 for the array, another $3,000 in charge controllers, and the batteries will be ridiculous money; possibly $30,000.

    Looks more like $100,000 than $50,000.

    If you re-evaluate your needs you could plan a system to run "most used" items and just fire up the big gen as-needed. Off-grid power is very expensive, and there's no way around it.
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Need help with 3-phase solar system

    I just gave trying to use a SunnyIsland in a hybrid system. Main problem is they are expensive and only 120Vac - to work with a GT inverter, you need either their "smart" transformers ($1500), or stack another SunnyIsland. You could go with 4 SunnyIslands for about $20,000 (they are made to play together) and two 5kW SunnyBoys for $5000 and then a 20kW 3ph transformer to tie in. 12kW of PV solar is going to be $20,000 installed, huge battery bank - at least another $20k... Maybe think about what your absolutely necessary loads are during an outage?
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Need help with 3-phase solar system
    agibbstx wrote: »
    Since you were nice enough to post that, I'm gonna steal it from you. :P

    I need to design a grid-tie hybrid PV system (I'm using this term to describe a photovoltaic system that normally interacts with the power grid, but includes a battery bank and other components to allow the system to function off-grid if needed) that can support 40 kilowatt-hours of power use daily while off-grid. Ideally, my system should support 20kW of "3-phase 480/277Y" power, and should be able to integrate power from a 30kW three phase generator to cut in should the power outage last. I am willing to spend $50,000 on this system, not counting the generator.

    That said, in response to the earlier messages, I was under the impression that adding the SunnyIsland inverters along with a transfer switch would allow the sunny island / generator to activate the grid connect side of the primary inverter and allow it to continue to deliver solar power. If I'm wrong, let me know. I design building automation systems for a living, but all these solar options are driving me up a wall.

    One thing to consider is how important it is to you for your PV system to continue producing power during an outage. Grid tied PV is a strategic tool that offsets your electrical bill over time. If outages are rare and/or short lived, the contribution to your bottom line from the PV continuing to produce during outages will be minuscule compared to what it will cost you to build the capability for it to do so into your system. If you must have power during outages, a more cost effective solution may be to install a transfer switch and a generator to provide power during outages and let the PV system shut down.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Need help with 3-phase solar system

    You have some options on how you arrange the SunnyIsland and Sunnyboys and how much battery you choose to use and how often you want the generator to start e.g.:

    1. Full power available from batteries: 2 x Sunny Islands per phase, 6 in total gives you 30kW available purely from the batteries. The GTI sunnyboys can be twice the capacity of the sunny islands, so you could have up to 20kW per phase in solar PV. Sounds like you only need 10kW per phase, so on a sunny day you'll have a total of 60kW available from the system (batteries + GTIs)

    2. Full power only available from generator, batteries are just there for less than peak loads and to handle the switchover to generator power: 1 x SunnyIsland per phase, and 10kW of PV per phase, so during sunny weather you still have 5kW + 10kW per phase, but if a cloud passes by then you only have 15kW total from the sunny islands. So they would have to be configured to auto-start the gen in that situation.

    SMA also have another product out aimed to work just with diesel generator + PV: http://www.sma.de/en/industrial-systems/hybrid.html Not sure about tech specs, it may only be available for larger systems > 300kW
  • agibbstxagibbstx Registered Users Posts: 3
    Re: Need help with 3-phase solar system

    Thanks for the advice, folks. You've given me a direction to head with this. I knew this stuff was complex, but never realised there were this many options. I'm thinking I may scale back my grand ideas and just start with a simple grid-tie system to offset some of my usage. I'll leave the grand "Hey We do everything Solar around here" plans for some future expansion.
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