Daily generation profile Irregularities

[JamesLenton]

Hello, 

Please can you help explain why irregularities like the one shown in the image attached occur in PVsyst? In this instance power drops from 15 MW to 0 MW in 30 minutes, mid-day in the summer.

To me this seems impossible, even with partial cloud cover. Could be a result of poor weather data, however I experience similar things with Meteonorm and PVGIS.

[Linda Thoren]

Hello,

To better understand the results, you can consider adding additional parameters—such as irradiance—to assess whether a drop in production is due to variations in weather data or other factors.

 

In the Advanced Simulations, you also have the option to export hourly data as a .csv file, allowing for deeper analysis of any relevant simulation parameters.

[JamesLenton]

Hello,

The cause of the drop appears to be the irradiation. Do you know why this could occur, it seems unrealistic.

[Linda Thoren]

Indeed it seems a bit surprising that the global irradiance would be 0 for a few hours in the middle of the day, but indeed possible. Using another weather data provider, do you see similar drops in irradiance?

If you import a weather file with missing data, these hours will be considered as 0 in PVsyst. 

[JamesLenton]

Hi Linda, 

We tried PVGIS and Meteonorm and saw similar anomalies on different days also. Weather data imported from those 2 sources shouldn't have missing data however?

James. 

[Auriane Canesse]

Hello James,

If the dip in irradiance is not due to missing data, I would need your files to look into this issue in more detail.
Could you send your project at support@pvsyst.com ?

Auriane

[JamesLenton]

Hi Auriane,

I have since made change to that variant, and when re-running it I am not seeing anything as extreme as the situation I posted above. However, there are still some very fast drops from almost max power to very low power (but not zero).

I have sent across the project files to PVsyst support email anyway for you to investigate.

Kind regards,

James.