Energy Generated not Always Correct


I have a Goodwe inverter and I’m using script to upload my data. The chart for power across the day seems to be correct everyday, but on days where there are clouds and the power output goes up and down a lot the total energy generated in not correct.

Check out my system “Sun Sucker 5000” on 24 May 2019 and 30 May 2019. Inverter reports 21.8 and 17.5 kwh respectively. While PVOutput has 2.18 and 23.8 kwh. Anyone have any ideas?


On the 24 May 2019 your average power was reported in only double digits all day. Your Power was in the expected range. The Output is calculated on the average power figure that is why the value is low for that date. Apparently you have just started sending your data to PVOutput and may have made some changes to the settings during the process. If you go through the daily data you will see the average power curve (yellow) starting low and each day approaching the power curve (green) then exceeding it.
Not sure why this is happening unless your inverter setting are being changed by your installer or manufacturer of the inverter. I have noticed that different inverters have very different characteristics. Mine is Solaredge and the Power and Average Power curves are almost identical within a few watts at any time of day for the past two and a half years.


Yes. I might have changed something in the beginning, but I haven’t recently, and I have the opposite problem on 30 May where the average power is greater than the power curve and I got a higher output rather than a lower one. So far these are the only 2 days I’ve had with clouds where the power has cycled up and down. Not sure where the weather data comes from as it is completely wrong saying most days have been cloudy when in fact most have been sunny since I’ve had the system. Today was cloudy with up and down power as well so I will keep uploading and see how it goes. Thanks for looking lwsmiser.


I did some more analysis for two of the days. It looks like it might be the scaling factor changes from day to day. 31/5/19 almost perfectly correlates the green power curve to the yellow average power curve. The yellow values are about 88% of the Green values. I’m not sure why it changes from day to day. The fact that you aren’t making any changes in the settings you control someone else may be…either the installer or the inverter company. My system never shows such large deviations between the two curves even on partly cloudy days. They are usually within 5 or 10 watts of each other.