PVsyst's forum

A copy of the SIT file contents appears to be stored in the PRJ file and in each VC# file.

Is the information in the PRJ file and/or the VC# files updated when the SIT file changes?

Yes, the Site file (*.SIT) and the meteo file (*.MET) are associated to the project when opening the project.

Now if you have performed a simulation with a given site, the variant file (*.VCi) will store the values of this site as Input parameters of the already performed simulation.

I'm not sure I fully understand what you mean by "associated". Does PVsyst detect when the information in the SIT and/or MET file is different from the PRJ file? Or do the SIT and MET file contents always get copied to the PRJ whenever the PRJ is opened? Is the PRJ information copy perhaps more of a back-up in case the SIT or MET file get lost?
And if the variant is simulated again, will it use the data from the VCi file or from the changed SIT and MET?

This question has been unanswered for almost two years, but actually it would still be useful to have an answer...

The PRJ does not backup MET. If a project is transmitted without the MET file, you will not be able to run the project with the same meteo source. Also, it stated that the variant stores SIT data (not MET data), and not the PRJ file. But when viewing a PRJ and SIT file, both contain SIT information. If a SIT or MET are updated, and the PRJ/SIT are saved, the next simulation will run with the updated values.

This is easy to check. Pick a location for your site next to a steep hill or mountain and run with a site file on the low ground and high ground. Your elevation will update in the report, and also if the coordinates change more than two decimal places, they will update also. Another check is to use the PVGIS horizon feature with two different SIT files. This function pulls coordinates from those listed in the SIT file.

Thanks for responding!

Let's talk about the SIT file first, since that is what I was originally asking about. The other day I deleted one, and my simulation still ran. Is it right to conclude that it is no longer required?

This seems to contradict your observations though...

I dont believe it is contradictory. Simply deleting the file does not change the already existing SIT data in the PRJ/VCi.

The SIT data is stored in the variant and project file (you can see this in text editor) . If the project is updated with new site data and the simulation variant is saved, the variant/project will update with the new values. You can delete the SIT file and still run because there is still the site data in the PRJ/VCi file. I just tested changing the site file, and checking in text editor the PRJ and VCi files. The update to contain the new data.

edit: I see the error I wrote; in a way it is backing up the SIT file, so yes that was incorrect. Edited for correction. However MET files need to transfer with projects.

Ok, so PVsyst keeps the three copies of the SIT contents in sync with each other.

I guess ultimately I wanted to understand the reason for storing these SIT details three times. If they are simply always kept in sync, then it doesn't seem be done to address a user need. Perhaps it just made life easier for the program/programmer to do it this way?