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  • Poor Performance of System?

    Almost 2 months ago I installed a 4.48kW system consisting of (16) solarworld 280 W panels with Enphase M250 inverters. The system is in NY. The array has a low tilt (12 degrees) and the azimuth is about 215.

    I have been monitoring the system via Enphase's online monitoring system, and I don't believe that it is putting out what it should be doing. It seems like October was a cloudy month (based on nothing more scientific than my observations) but I had hoped the system would be performing better than it is. So far it has only put out 389 kW. This averages out to about 7.7 kW/day.

    For the most par the array is shade free, and according to my pathfinder reports for October/November the system should have produced almost twice as much.

    Any thoughts?

  • #2
    Originally posted by AE3 View Post
    Almost 2 months ago I installed a 4.48kW system consisting of (16) solarworld 280 W panels with Enphase M250 inverters. The system is in NY. The array has a low tilt (12 degrees) and the azimuth is about 215.

    I have been monitoring the system via Enphase's online monitoring system, and I don't believe that it is putting out what it should be doing. It seems like October was a cloudy month (based on nothing more scientific than my observations) but I had hoped the system would be performing better than it is. So far it has only put out 389 kW. This averages out to about 7.7 kW/day.

    For the most par the array is shade free, and according to my pathfinder reports for October/November the system should have produced almost twice as much.

    Any thoughts?
    From what you've posted, it doesn't sound like anything is wrong. Approximately where in NY are you? A SAM simulation for long island with your system would estimate something around 670 kWh for Oct / Nov combined, with "typical" weather and relatively low loss factors. Weather that is cloudier than "typical" would result in less, or there could be other installation factors not captured in the way I'm modelling it.

    You might want to read this thread for a better explanation of the low production this time of year.

    If you would like to share your pathfinder reports, perhaps there is something in them that would explain why the estimates are so much higher.
    CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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    • #3
      Follow the link and find an Enphase system around your area. It should give you an idea how your system should perform:


      https://enlighten.enphaseenergy.com/public_systems

      Comment


      • #4
        Originally posted by AE3 View Post
        Almost 2 months ago I installed a 4.48kW system consisting of (16) solarworld 280 W panels with Enphase M250 inverters. The system is in NY. The array has a low tilt (12 degrees) and the azimuth is about 215.

        I have been monitoring the system via Enphase's online monitoring system, and I don't believe that it is putting out what it should be doing. It seems like October was a cloudy month (based on nothing more scientific than my observations) but I had hoped the system would be performing better than it is. So far it has only put out 389 kW. This averages out to about 7.7 kW/day.

        For the most par the array is shade free, and according to my pathfinder reports for October/November the system should have produced almost twice as much.

        Any thoughts?
        That doesn't sound too off the mark. See recent prior threads about how winter output is lower than summer output.

        Comment


        • #5
          Originally posted by AE3 View Post
          Almost 2 months ago I installed a 4.48kW system

          I have been monitoring the system via Enphase's online monitoring system, and I don't believe that it is putting out what it should be doing. It seems like October was a cloudy month (based on nothing more scientific than my observations) but I had hoped the system would be performing better than it is. So far it has only put out 389 kW. This averages out to about 7.7 kW/day.

          For the most par the array is shade free, and according to my pathfinder reports for October/November the system should have produced almost twice as much. Any thoughts?
          I think you mean it produced 389 KWHour, or 7.7 kWHour/day. If so, I would say that is entirely
          consistent with cloudy weather, and my own results. Expect twice as much when the sun
          shines unobstructed during mid day. Bruce Roe

          Comment


          • #6
            Originally posted by AE3 View Post
            Almost 2 months ago I installed a 4.48kW system consisting of (16) solarworld 280 W panels with Enphase M250 inverters. The system is in NY. The array has a low tilt (12 degrees) and the azimuth is about 215.

            I have been monitoring the system via Enphase's online monitoring system, and I don't believe that it is putting out what it should be doing. It seems like October was a cloudy month (based on nothing more scientific than my observations) but I had hoped the system would be performing better than it is. So far it has only put out 389 kW. This averages out to about 7.7 kW/day.

            For the most par the array is shade free, and according to my pathfinder reports for October/November the system should have produced almost twice as much.

            Any thoughts?
            Where are you in NY? I am in Staten Island NYC.
            I have a 8.2kW system. It made 524 kWH in October (average 17.47kWH/day).
            If my system was 4.48kW, then the numbers would 286 and 9.54
            7.7 is not far from 9.54.

            Get your number in October only and calculate the average per day and compare with 9.54.
            We are going to get less in November!
            8.2KW 32x(PVmodule+inverter)+online monitoring

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            • #7
              Pretty Complicated!

              I checked out the Enphase site of the panels in my area (very cool), but it is pretty hard to really compare panel performance just by a few hand calculations. You have to account for the orientation (tilt and azimuth) of the panels as well. If my panels are at 150 Deg and my neighbor's panels are at 240 Deg, we will get different performance for the exact same panels. You can't look at a percentage of performance month by month between two systems because the angle of the sun is different by season depending or orientation. Short of running the CSI EPBB model for the two systems, you could look at month's production percent difference by year. Is there an easier way to do this that I'm missing?

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              • #8
                What are you trying to do.. grade the real-time performance of your system? PVWatts will give you some idea of the seasonal variation to expect, but it would not be surprising to see +/- 30% in any given month due to the difference between modeled weather and actual weather, among other things.

                If you really, really want to get into it, you could drop a grand on a personal weather station that could be calibrated every so often for accuracy. Many people who have installed them upload their data and can be accessed... by clicking around in the map here you might be able to find a weather station in your area that reports solar irradiance, and see how well its results scale to your production. As you've said, there is an angle of incidence correction for your specific array, but that can be estimated in a spreadsheet. You will want to filter the map by city / metro area, and I've found the APRSWXNET/CWOP network to filter the results down somewhat. For example, I found this one in the Camarillo area. I haven't found an easy way to just filter the stations for those with solar irradiance.
                CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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