That's because ocean PV is... unrealistic; the wear and tear on these things is immense. I am guessing windmills are affected less, with the blades being made out of fiberglass and most of the construction being above the waves.
Source: I made it up, I'm a software engineer not a maritime power expert.
I work in Oceanography.. The solar panels on individual buoys also get cleaned by rain, and can work ok vertically because of reflections. We have special diode bypass panels made so if 10% is covered in poop (SeaLion poop in our case) only 10% of the power is reduced.
Our biggest problem with small wind turbines on buoys is fishingpeople throwing line into them.
Source: I made it up, I'm a software engineer not a maritime power expert.