Horizon Loss management in meteo data

[LoicA]

Hi everyone,

I am currently working on a project in the La Réunion island, we have a ground power plant there and we are doing the PVsyst again to compare with the real data.

We have one "issue" or at least one "hesitation" about the horizon impact on the power plant (there are a couple of mountains there and the horizon line is about 8°).

The meteo data available are one Meteonorm station (180km climatic distance...), PVgis; and why not the NASA SSE (not tested yet).

I am wondering about the data of Meteonorm and PVgis : do they contain the horizon loss ? I have read all the data available on the forum and the PVsyst help but it's stil not clear.

I hope it's correct but I understood that the data on Meteonorm and PVgis have a "horizon correction" according to your words. What does it mean ? Are they horizon free (higher value of irradiation) ?

I have read one process about the management of the data to do a correct simulation including the real horizon line:

-Use the monthly value with the horizon correction

-Calculate the hourly data

-Apply the horizon correction with the "original" horizon. What are the horizon correction process/calculation, and what do you call the "original" horizon ?

-Generate the monthly value

-Apply the horizon correction on these monthly values. Again, what is the horizon correction calculation ? At this step it seems that the data is horizon free

-Generate the hourly data

I would be really interested to have answers to these questions,

Thank you in advance