I' reading up on solar panels and contemplating few design ideas. I will most likely build a covered pergola, that will be 12x40 in dimensions to support the panels. It will be slightly slanted at about 30 degrees.
Originally I thought about placing 2'x20' or 4'x20' panels horizontally, but it seems that vertical orientation is preferred and sagging might be an issue even at small angles of incline. Another possibility is to place 12' or 8' long panels vertically to avoid that issue all together.
I read that the panel expand and contract with the temperature. Do they do that along 2 axis, the same directions as tubes go or perpendicular? I would have to put a good number of vertical panels in an array and I'm wondering how to accommodate if expansion takes place perpendicular to tube direction.