If you want to play it safe for cleaning conny roofs or solar panels, just check the ph value which you will find on the msds for all cleaning products. its safest to use a cleaner thats non-caustic,non-corrosive, most high alkaline based cleaners like TFRs for example are caustic and corrosive and will cause detrimental damage to surfaces from continuous use, if the ph value is over 10.5 its these products are more likely to cause the damage as they are highly alkaline, there are many janitorial suppliers in the UK stocking safer products which are non-caustic,non-corrosive, and will not cause detrimental damage to surfaces.just do a google search as there are many in the UK.