Probably warm soapy water,use a long handled flat based mop and window blade (rubber)
If you go in the garden centres they do a long handled tool, you can clip rakes, hoes etc on, but they also have loads of other attachments, one might suit you.
There are firms that specialise in cleaning consevatories, google your area.

If the roof is polycarbonate, use warm soapy water with a soft, foam type mop. Rinse off with a hosepipe.
If it's glass, you can use a pressure washer, but watch out for the ridge, which may be vented.

warm soapy water and a mop then rinse with a hose pipe hope this help

you would clean ypur roof just the same as you would your windows,hot soapy water