PV Modules Have Moved
A PV array should solidly attached to its racking and the roof. Modules should be straight and square. Gaps between modules should be consistent and even. Clamps should bear evenly on module frames and should be square to the frames.
If your array doesn’t match this description it was either improperly installed in the fist place and/or has moved since the original installation. Movement could be caused by poor installer practices, mis-matched racking parts, weather effects, thermal expansion, or other reasons.
Loose modules are an immediate safety concern and should be inspected as soon as possible. You want your solar modules to stay where they belong and not end up on the ground or worse.