What can be the cause of some strange ray shadows artefacts on a perfectly flat surface? First of all I have to say that I am really new in the world of Computer Graphics. I apologise if some of my questions may appear trivial.
I am currently using a non-commercial ray tracing and physically based rendering software. I didn't have any problems with this until now : I have a scene where an .obj file representing a satellite is placed surrounded by a environment map light.
Here is an exemple of my problem appearing on the solar pannels :

I have no idea where these strange forms could come from. I have to say that for this picture, the .obj file representating the solar pannel is a very simple parallelepiped. I also tried to suppress the other face of the object but nothing changed.
I saw this exchange (Cause of shadow acne) that could maybe be related to my problem, but if someone has an idea of what could be the cause, I would be happy to hear it!
Thank you to all and have a nice day.
It appeared that it was exactly the problem explained in the link of my original post (Cause of shadow acne).
The shadow function offset has been increased and the problem is solved!