This queston would perhaps be an ocean engineering question, but since we don't have a forum for that, I thought mechanical engineers would have some idea about this. My background is electrical engineering, and I have little knowledge about the mechanical issues when operating at the surface in the ocean. I am wondering how practical it is to use solar power in automomous, ocean-based systems like buoys. In particular, how much effective power can be extracted from a given surface area? Also, I'm wondering what practical issues there are. My questions are not related to the electrical side of things since I have a good idea of the operation and efficiency of solar cells; and, what I don't know, I can readily look up. The things that seem harder for me to figure out are the limitations due to difficulty of facing the cells toward the sun, and the likelyhood of salt-accumulation or bird "stuff" blocking the light. Also, I wonder about stresses in storm conditions, and how a system would survive for extended periods. Can anyone address some of these issues, or any others issues I may not have thought of? Basically, I'm trying to figure out what net efficiency loss there is when using solar cells on the ocean surface compared to on land; and, for what period of time, the resulting efficiency could be maintained.