Donatas:
Your system of placing 4 detectors, one on the center of each edge of the solar panel, seems like it would work quite well in a theoretical sense. But I would like to pose two questions.

Does your proposed system work best when the panel size is very small or infinitely large, relative to a given light source?

For a given panel size, does your proposed system work best if the light source is very close to the panel or infinitely far away?

Michael Karas