Perhaps not in this case but the usual cause of leaks on Solar systems is the ball valve in the small header tank.
I have to replace mine every year as the valves are poor quality and I havn't found any in the UK that would fit in the tank.
When it leaks it sometimes runs down the panels, sometimes down the tiles and sometimes down the ironwork.
Regarding the leak I would get it sorted before any possible frost/freezing weather conditions.