I would expect the maintenance on these floating systems to be more expensive than the ones on land, but I don't really know the numbers. As far as I understand, the company that made these are not currently selling them to private people, so they have not really told the public about the costs.

I actually learned about the tidal wave electricity a while back. As far as I remember, it can be a great source of energy, but cost were way to high. I also think there was a lot of trouble with maintenance. Those tidal systems are in saltwater, so they get destroyed a lot more quickly than these solar parks (which are in fresh water).