Our boat came with solar vents (1984 Oday) and I think they are good for air exchange and venting overnight....reduces moisture buildup. One of them is not working this year so we may have to replace it.
I installed a solar vent and the moment I did it stopped working. This does not make a sailor happy after he has just cut a hole in the cabin top of his boat. I believe the battery in it has gone bad and will replace it when I find one that is the right size.