Designer Phil Pauley wants to coat our oceans with floating solar cell-covered balls. Their buoyancy could also make them viable as a wave-power system. It's purely conceptual at this stage, and with good reason: Until recently, wave power hasn't fared well as an alternative energy.
Anything that goes in the ocean is subject to immense forces (water being so much denser than air) plus "fouling," which is the inevitable accretion of biological material, from the microscopic on up to barnacles, that eventually encrusts most ocean-going debris so thoroughly that it eventually sinks.
So while these marine solar cells would probably be too high-maintenance to actually work, they're not completely outrageous. After all, even the Navy has figured out what appears to be a viable way to keep its ship hulls free of debris — using a little robot.
Floating Marine Solar Cells Harvest Energy from the Sun and Waves, Inhabitat.