i usually give a quick jet over with customers hose first to soak it ,then place a small ladder against the gutter and climb up , scrub the panels using a pole with a 10"swivel mop,with a pulex microtiger sleeve . down below i have a full bucket of water/washing up liquid mix ,i then swing the pole down into the bucket and then back up onto the roof (all while standing on the ladder )
then using the customers hosepipe wash off and move along to the next place