You should be able to clean the majority of conny roofs with wfp. Sometimes when access is tight you will benefit from splitting a 3m double so you can climb up above the gutter line, this is a personal preference as I find the angle better to clean and it's faster - WFP will remove all that green and black, but we always g101 as it speeds up the whole process. Lichen can be hard work, there are various ways to tackle this,
Check with customer with glass roofs, if self cleaning no chemicals!
Darran