Late Afternoon Spikes in Hourly Output

[BCON0500]

Hello, potentially a newbie question as my experience with the program is still in the early stages, but I was hoping someone has run into this issue before and might have some suggestions.

The following graph is of a day's hourly output and has 4 trends. I'm looking to understand what potential parameters I'm using that might be causing the inverters to increase in power output in the afternoon despite a declining GHI. I was hoping that the results were a result of poor shading parameter inputs. However, after including shading representative of the installation, the increase of output despite declining GHI remains (although the spike has become less drastic). Has anyone run into similar issues in the past?

Green = GHI

Light Blue = Meter Data

Dark Blue = PVsyst (No Near Shading)

Orange = PVsyst (Near Shading w/ Backtracking)

 

[Linda Thoren]

Hi,

The output will depend on your type of system. A fixed tilted system with an optimum tilt and azimuth will peak when the GHI peak, a east west system will rather peak in the morning and evening. This is also what you see a bit with trackers with trackers with a north-south axis during months where the sun's position is relatively low. 

Indeed such a drastic peak in the end of the afternoon looks strange, is the irradiance data and the hourly output aligned? Do you have an have an azimuth? Is there a horizon line? 

To be able to analyze this in more detailed, please send your project to support@pvsyst.com

Kind regards  

[linkeshd]

Hi @BCON0500, I would love to know more about your simulation.  Is the meter curve based on actual measurements or is that also PVSyst output after transformer losses?  Does the PVSyst output comport well with actual generation?  Thank you!