How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?

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Jerry
Jerry Registered Users Posts: 19 ✭
in General Solar Power Topics #1
Hi All,

Regarding my finding in the past week, i found something interesting.

Fronius is using Mono-phase design on its 10kw and 11.4kw. But as what i know it is better to use for 3-phase design for a inverter had > 10kW output, otherwise output current mightbe higher (less efficiency).

I am not sure what my founding is corrrect?

On the otherhand, i am not sure does UL1741 required balance output of each phase of a 3-phase system when system is >= 10kW as VDE required?


However, I think mono-phase is a proposed configuration of a residental and light comerical installation, is it ?

I am looking for advice on my question here, many thanks!

Jr. PM
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?

    I am a little confused...

    What is your question about? In the US, homes have 120/240 VAC split phase utility service. It would be very unusual for a home to have 3 phase power (in other countries, such as a couple in europe I have read about here, 3 phase power is available for home service).

    Also, in the US, 10 kW for Grid Tied Solar is the typical dividing point between a "don't care" generic installation and an installation that has much more in the way of requirements/utility engineering/billing/etc. (above 10kW is not a "small generator", at least in California).

    Three phase power is fairly common even in small commercial buildings.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Jerry
    Jerry Registered Users Posts: 19 ✭
    #3
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?

    Sorry, I means how popular for a 11 or 12 kW system in a farmer house?

    if you have 10 kWS panel, would you go stick with one inverter (11kW or so ) or use two 5kW inverters?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?

    It depends... The larger home single phase panels are 250 Amp at 240 volts or 60 kW peak. And the maximum solar GT inverter system would be around 12 kW maximum single phase system.

    So, for the larger majority of homes, there is probably not much need for a 10kW vs two 5 kW (or whatever) inverters. Whatever works out best for pricing ($$$/watt) is probably the best choice.

    Since above 10kW is probably a "commercial sized" system--The whole three phase vs single phase is going to really depend on the local power needs and the utility's requirements.

    A "farm home" is going to, most likely be, a single phase power system.

    A farm with signification electrical needs (processing equipment, refrigeration, shop for repairs/welding/etc.) or one that is looking to install a solar field for commercial sail (much larger than 10,000 watts), then they will probably have 3 phase power and then it will have to be engineered to support 3 phase power...

    I am not the person to ask--Perhaps others here with direct experience in the >10 kW systems can give you more help.

    Are you looking at design/manufacturing 5-10 kW inverters? Or are you looking to design 100-500 kW GT inverters?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #5
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?

    My GT is a 12.5 kW system with 2 6000 watt inverters. I think this is about as large as any residential system needs to be to allow for all the standard amenities in Phoenix, AZ like dual ground mount AC units, a deep freeze and fridge, a couple computers, ceiling fans, flat screen TVs ... while making the overall electric bill near zero dollars for generation. In fact I expect a utility check back next January for the excess generation in Oct.-Dec. time frame.

    I suspect other areas of the country can get by with much less.
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #6
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?

    Fronius would be my second to last choice, last choice would be PVPowered

    SMA and Xantrex both have best in class inverters that a pair of would work well for you. There is no advantage of having a single 10kw+ inverter vs a pair of 5kw units and for tracking, having two is better as its unlikely you will have 10kw of panels that have the same angle, , orientation or thermals.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #7
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?
    Solar Guppy wrote: »
    Fronius would be my second to last choice, last choice would be PVPowered

    Hmmm and what is your rational? So far my PVPowered inverters are doing exactly as expected.
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  • nvyseal
    nvyseal Solar Expert Posts: 108 ✭✭✭✭
    #8
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?

    and my Fronius 5100 is churning out 42kwh on a sunny day right now with a 4.7 system. I don't think that's bad :blush:
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #9
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?
    Solar Guppy wrote: »
    Fronius would be my second to last choice, last choice would be PVPowered
    So far I am happy with my fronius inverters and they didn,t abondon thier customers like xantres did with the SW 4024. I will mever forgive them for that and will never buy anything Xantrex Makes S:Dlarvic
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #10
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?
    solarvic wrote: »
    So far I am happy with my fronius inverters and they didn,t abondon thier customers like xantres did with the SW 4024. I will mever forgive them for that and will never buy anything Xantrex Makes S:Dlarvic

    Fronius has discontinued older models, no different than Xantrex
    nvyseal wrote: »
    and my Fronius 5100 is churning out 42kwh on a sunny day right now with a 4.7 system. I don't think that's bad :blush:

    Other users haven't been so lucky, there are two thread on this forum with all the ugly details
    solar_dave wrote: »
    Hmmm and what is your rational? So far my PVPowered inverters are doing exactly as expected.

    Based on actual testing, their units I tested, had mppt tracking issues, startup issues, reported power about 5-7% above actual, exaggerated performance claims, they ( PVP ) was the reason CEC requires UL verification of performance. The models I test are no longer produced, so if your happy it would be good to see they improved
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  • Jerry
    Jerry Registered Users Posts: 19 ✭
    #11
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?
    BB. wrote: »
    It depends... The larger home single phase panels are 250 Amp at 240 volts or 60 kW peak. And the maximum solar GT inverter system would be around 12 kW maximum single phase system.

    So, for the larger majority of homes, there is probably not much need for a 10kW vs two 5 kW (or whatever) inverters. Whatever works out best for pricing ($$$/watt) is probably the best choice.

    Since above 10kW is probably a "commercial sized" system--The whole three phase vs single phase is going to really depend on the local power needs and the utility's requirements.

    A "farm home" is going to, most likely be, a single phase power system.

    A farm with signification electrical needs (processing equipment, refrigeration, shop for repairs/welding/etc.) or one that is looking to install a solar field for commercial sail (much larger than 10,000 watts), then they will probably have 3 phase power and then it will have to be engineered to support 3 phase power...

    I am not the person to ask--Perhaps others here with direct experience in the >10 kW systems can give you more help.

    Are you looking at design/manufacturing 5-10 kW inverters? Or are you looking to design 100-500 kW GT inverters?

    -Bill

    I am looking forward to design a new product, range is bettwen 10 ~ 15kW with 3 phase (1-phase is optional under discussed for 11.5 as Fronius).

    But I am not sure how is US market will shift, regarding the information that I had from SEIA, installations of Residental <=10 had increased but TL Inverters are looking acceptable on the market, but less people install them.

    how pupolar is Transformerless nor transformer design?
    10 to 12 KW for single pahse or 3-phase?
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  • Jerry
    Jerry Registered Users Posts: 19 ✭
    #12
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?
    Solar Guppy wrote: »
    Fronius has discontinued older models, no different than Xantrex



    Other users haven't been so lucky, there are two thread on this forum with all the ugly details



    Based on actual testing, their units I tested, had mppt tracking issues, startup issues, reported power about 5-7% above actual, exaggerated performance claims, they ( PVP ) was the reason CEC requires UL verification of performance. The models I test are no longer produced, so if your happy it would be good to see they improved


    How is experience on the PV Powered Products (last choice)?
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #13
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    Re: How good is Mono-phase design for 10kW or 11.4kW inverter (Fronius)?
    Solar Guppy wrote: »
    Based on actual testing, their units I tested, had mppt tracking issues, startup issues, reported power about 5-7% above actual, exaggerated performance claims, they ( PVP ) was the reason CEC requires UL verification of performance. The models I test are no longer produced, so if your happy it would be good to see they improved


    I have seen no startup issues, only once did the system reset and restart the 5 minute count down to setup tracking midday and I didn't get to it before it restarted to see the fault. We have over a years operation under our belt. Occasionally the TED reports a masive momentary dip but I can only track this to the TED data and suspect it is that devices problems. Power output here is tracked by the TED setup and it looks about exactly correct for 80% ish efficiency for the rated panel output. (Sometimes better, sometimes worse mostly attributed to weather conditions & temps.) The TED data seems to line up with the display reported watts within a 100 watts or so per inverter.

    PVP5200 approvals:
    UL 98 13th Edition Yes
    Enclosed and Dead-Front Switches Yes
    UL 1741 Nov 2005 Revision Yes
    IEEE 1547 Compliant Yes
    FCC Class A & B Yes
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