I'm downslope of a 50 acre solar farm.  It definitely increased the amount of water that runs onto me.  First, the construction compacts the soil so it doesn't absorb into the soil.  ie. loose ground verses a road.  This has improved over time as the traffic has now stopped and the interseeded grass between the panels becomes more established.  Second, when the rain runs off of the panel, it hits the same spot on the ground.  From there, the water begins to channel and run.  That's my experience.