Moss absorbs and retains water.
Moss on roof tiles is it a problem.
The presence or absence of sunlight dictates the amount of moss or algae growth.
If you remove moss from the roof then you will reduce the possibility of tiles suffering from winter cracks.
The reason being in most instances moss on roof tiles is rarely a problem and only needs to be removed if it is blocking gutters outlets and other drainage points on the roof.
Moss on roof tiles can cause multiple problems such as wood rotting and the obstruction of drainage points.
Keep your trees well trimmed to lessen the debris that falls onto your rooftop.
Roof moss prevention if the above sounds like too much of a hassle which honestly it likely does then know that the most effective method is to prevent the problem of moss on your roof in the first place.
We had a problem where in very heavy rain the moss build up in the valley was causing water to back up and go under the tile above.
Fortunately for us the very nice roofing man we called to investigate the problem very quickly discovered what the problem was and fixed it without even charging us.
Shaded areas exposed to frequent damp cool weather will quickly encourage moss to grow on your roof.