Tractor kit.

Not seen one of these on a tractor before.  For some reason I have always enviasged cleaning solar PV cells to be done by people with cloths, ladders and distilled water.  Apparently not: the brush swings to one side and the rotating brush is fed with filtered and ion exchanged soft water from the tank on the trailer (the brushes felt very stiff and something must happen to adjust the angle of the brush to exactly match the angle of the panels).  Tractor, trailer and accompanying pickup do a 150 mile round trip to do this job - I wonder whether the diesel was included in the carbon footprint of the solar farm.  The driver assured me the brush is taken off the front of the tractor before he sets off on the public highway.