As previously mentioned 4 years ago.
About this time last year I brushed our motorhome roof with a mild detergent then sprayed a weak mixture of our Yates Surrender Mosskiller concentrate containing the same active ingredient as all those other products on the market (benzalkonium chloride) that do not contain a 30 second bleach (usually Sodium Hypochlorite).
We still have 990ml remaining in our 1000ml container.
In the past the first area to blacken with mould was the well shaded gap between the solar panels. I inspected the roof recently and can report that more than a year after spraying there is still no visible mould in those gaps.