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Thread: 480V vs 208V inverters

  1. #21
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    Quote Originally Posted by beanland View Post
    Issues to consider:
    (4) It is normal for a 600Vdc system to be used for a 208 or 240V AC connection. At 480V, a 1000Vdc system is used. For a 1500Vdc system, they often operate at 600Vac. Check the voltage rating of the array, the modules are 600Vdc rated, stick with a 208/240V inverter and skip the transformer.
    (5) An autotransformer is YGyg and has a smaller core so core loss goes down. A good choice if you must use 480V inverters on a 208V service.
    FWIW, fronius 208 inverters, and even their 240 single phase ones, do 1kv strings.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  2. #22
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    Quote Originally Posted by electrofelon View Post
    FWIW, fronius 208 inverters, and even their 240 single phase ones, do 1kv strings.
    I believe beanland's point was that the inverter our friend Zee has chosen might not be suitable for an old array where everything - including panels - might be wired and rated for 600V max. Seems like a valid concern. MPPT range on the Symo 480s is 500-800? Which leaves you with a voltage constraint, perhaps, of 500-600V, which strikes me as narrow.

  3. #23
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    Quote Originally Posted by jaggedben View Post
    I believe beanland's point was that the inverter our friend Zee has chosen might not be suitable for an old array where everything - including panels - might be wired and rated for 600V max. Seems like a valid concern. MPPT range on the Symo 480s is 500-800? Which leaves you with a voltage constraint, perhaps, of 500-600V, which strikes me as narrow.
    Oh ok , good point. I hadn't considered that a 480 inverter might have a higher low voltage spec. I just checked it looks like the symo's isn't that much higher than their 240 inverters, 50-100 volts higher. Sunny tripower is quite a bit higher.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  4. #24
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    SYMO 24.0-3 480:

    Operating voltage range: 200-1000V
    DC startup voltage: 200V
    MPP-voltage range: 500-800V

    Array rated Vmp: 418.2 V (17 @ Mitsubishi 170W (24.6 Vmp rated each) per string)

    Symo has a huge V range input window!

  5. #25
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    Based on random measurements in field I figure in real world (heat) Vmp goes down about 25% from rated Vmp.
    Rate Vmp is 418.2 Vmp.
    So my array might run around 300 VDC.

  6. #26
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    Quote Originally Posted by Zee View Post
    Based on random measurements in field I figure in real world (heat) Vmp goes down about 25% from rated Vmp.
    Rate Vmp is 418.2 Vmp.
    So my array might run around 300 VDC.
    So isn't that below the inverters mppt window?
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  7. #27
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    So is the deal with these inverters that they will operate below 500V but just not utilize their MPPT algorithm, or not guarantee that it will settle on the actual MPP?

  8. #28
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    Quote Originally Posted by electrofelon View Post
    ... I do recall Mr Gunn stating that he has ran across inverters that speced a wye-wye, but I assumed that was one of those frequent cases of a manufacturer meddling in things they shouldn't care about.
    That was years ago. I suspect you are correct about the spec error; I always use wye on the inverter side and delta on the utility side now.

  9. #29
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    Quote Originally Posted by jaggedben View Post
    So is the deal with these inverters that they will operate below 500V but just not utilize their MPPT algorithm, or not guarantee that it will settle on the actual MPP?
    The MPPT range published on the datasheet, is the range where performance can achieve the published CEC weighted efficiency. It may operate lower than the MPPT range and still seek the array's sweetspot, but the inverter will have to activate boost converters, which hinders its efficiency. So the low input voltage limit of the MPPT range is a soft limit, not a hard one.

  10. #30
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    Quote Originally Posted by Carultch View Post
    The MPPT range published on the datasheet, is the range where performance can achieve the published CEC weighted efficiency. It may operate lower than the MPPT range and still seek the array's sweetspot, but the inverter will have to activate boost converters, which hinders its efficiency. So the low input voltage limit of the MPPT range is a soft limit, not a hard one.
    That rings a bell, that there are different ranges based in published efficiency - I have seen that before. But take a look at this and tell me what the difference between "rated" and " operating" mopt range is

    https://www.powerfromsunlight.com/ea...-1-input-data/
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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