What output can I expect from 6.5K system?

jimgerlv
jimgerlv Registered Users Posts: 1
in Advanced Solar Electric Technical Forum #1
I just had a new basic 6.5K string inverter system installed on my West facing roof. My SMA Sunnyboy 6000TL-US shows instant watts out as one of the monitor info fields.
I am seeing 4800W-5200W during the day. Will I ever see near 6500W being produced?

Any thoughts/info would be greatly appreciated.

Thanks!

Panels: Poly-Silicon Eoplly 285W (2 strings) 23 total
Location: North Las Vegas

I have a 45 foot run from panels to inverter with 12G wire.
I do not have on-line web monitoring.
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: What output can I expect from 6.5K system?

    Welcome to the forum.

    You probably won't ever see nameplate rating of the array, or at least not for very long and certainly not often. Those ratings are based on Standard Test Conditions which just don't happen in the real world. Under typical derating conditions around 5kW would be available from a 6.5 kW array, so really your numbers are in line with expectations.

    Things that make it worse include high temps, clouds, dust, and of course changing sun angle. Things that make it better include low temps, clear atmosphere, high elevation, and of course direct-on-panel sun.
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  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    #3
    Re: What output can I expect from 6.5K system?

    Hot days in VEGAS no way, and serious dust control in vegas, not to mention desert dust, you would be lucky to yield 5.8kWh AC on a perfect day if facing perfect south, you are facing west bound.

    Las Vegas average ambient temperature from july until august is 98*F, there are peaks of 105*, 98* is the average condition.

    So for every 1* celcius rise from STC you could be losing 2~5 volts depending, on the panels power tolerance %.

    Also I noticed 12AWG is your home run? Even if it is a 45' run there is still considerable voltage drop if the conduit has any sunlight exposure. (I.E) if its 100*F ambient, the conduit could be as hot as 125*.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #4
    Re: What output can I expect from 6.5K system?

    the best 2 months of the year in Phoenix are April and May.
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  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    #5
    Re: What output can I expect from 6.5K system?

    Also I hope for sure that when 12AWG was mentioned its 2 sets of 12AWG to the inverter for each string, I looked at your IMP/ISC specs makes no sense if you combine and have (1) 45' run 12AWG to the inverter. If its one set you are in some trouble with redundant voltage drop and temperature, you would want 25amp over current protection which means USE-2/THHN 12AWG, so it would have to be a really high temperature rated 12AWG, even so theres some voltage loss from resistance regardless of that footage.

    If its a single combined home run it should be a minimum of 10AWG THHN/USE-2 regardless of the length run.

    Also you are missing a panel. SMA has single MPPT not dual MPPT so the strings need to match, how would you have 11.5 panels per string? Your system is operating as if a 6.27kWh system because the inverter MPPT is selecting the lower voltage. This makes more sense. Facing southwest bound plugged into PV watts in your region your system is operating at 77% with use of 12AWG.

    You stated you are making between 4.8~5.2kWh so here's the math how your system is operating, it is not operating to a true 6.55kWh system because the strings are not balanced.

    6270Wh X .77= 4827.90Wh....... YUP, you are better off disconnecting a panel until you can afford another to match, and upgrade that home run to 10AWG THHN. Hope that helps.
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  • PVAndy
    PVAndy Registered Users Posts: 2
    #6
    Re: What output can I expect from 6.5K system?
    SolarPowered wrote: »
    Also I hope for sure that when 12AWG was mentioned its 2 sets of 12AWG to the inverter for each string, I looked at your IMP/ISC specs makes no sense if you combine and have (1) 45' run 12AWG to the inverter. If its one set you are in some trouble with redundant voltage drop and temperature, you would want 25amp over current protection which means USE-2/THHN 12AWG, so it would have to be a really high temperature rated 12AWG, even so theres some voltage loss from resistance regardless of that footage.

    If its a single combined home run it should be a minimum of 10AWG THHN/USE-2 regardless of the length run.

    Also you are missing a panel. SMA has single MPPT not dual MPPT so the strings need to match, how would you have 11.5 panels per string? Your system is operating as if a 6.27kWh system because the inverter MPPT is selecting the lower voltage. This makes more sense. Facing southwest bound plugged into PV watts in your region your system is operating at 77% with use of 12AWG.

    You stated you are making between 4.8~5.2kWh so here's the math how your system is operating, it is not operating to a true 6.55kWh system because the strings are not balanced.

    6270Wh X .77= 4827.90Wh....... YUP, you are better off disconnecting a panel until you can afford another to match, and upgrade that home run to 10AWG THHN. Hope that helps.

    It depends on which SMA Inverter it is. The SunnyBoy 6000TL-US-22 is a dual MPPT inverter, The SunnyBoy 6000TL-US-12 is a single MPPT inverter with very fussy stringing requirements

    Andy
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