Very nice Job Mark, But can I give you a little tip??
Next time you do a roof clean like that, (Plastic) use the custy's water to wash it, I have done loads like that with the custy's water, if its a glass roof then just give a final rinse with pure, it saves buckets of your own water.
I also find it pays to do the odd little Job for some custy's, well done Dude, nice Job.