Looks like a really nice habitat for seabirds to roost, make nests, poop on, etc. But of course they've thought of that!

This would make sense after every rooftop was covered with Solar PV and solar thermal and every parking lot had a shade structure topped with solar PV. Distance between power plant and power consumption matters, so putting a power plant from the load doesn't make a whole lot of sense unless you are out of better options.

There should be wave power generators at the hinges of this float, and a windmill on top of it - so that the power cable, maintainance crew etc. are efficiently utilized.

This sounds like a wonderful idea, but I fear the problems have been far underestimated and would be insurmountable.
Even if the 'wildlife' issue Schreibtribe mentioned isn't too troublesome (it would be!), there would be significant losses caused by spray and dried salt residue, let alone the corrosive effects.
Far more important, though, is this flippant belief that such pontoons could withstand rough conditions. Just how rough are we talking about? Sorry, but despite the best efforts I suspect such a construction would be smashed to bits by the first winter storm.

Maybe in warm climates in a secluded bay, out in the ocean in cold weather with nature's wrath and ice, ship traffic, cable anchors, & getting the power into land...

This is the ideal place for photovoltaics. They have 2% reflectivity, like water and so don't change the Earth's albedo. The required cooling water is right there. The Sargasso Sea is right on the equator and is where ships were becalmed. Plenty of biomass is available. Direct sea shipping is available. As in earlier times, population would migrate to an area of cheap energy. This is very telling, as reguards alternative energy, in that it doesn't support population migration.

The flotation system is an interesting wave harnessing power generation system all by itself if the continual change in pressures were scavenged. 24/7 as well.

Test off Catalina Island So CA, HI, San Juan Islands, WA, Hamptons LI NY, PR, Fiji, India, Vietnam, Taiwan. Problem: seabird poop on solar cells, water damage, salt spray, etc.

As clever as some things are on this proposal, I can't help but wonder about landlocked Austrian engineers designing ocean going structures. I agree with Peter Kelly below. The inefficiencies of salt masks, corrosion, transmission issues and assumed wildlife refuge, there needs to be more detailed thought. I speak as a retired oceanographic engineer with 45 years going to sea. I would love to see this succeed after mundane but very influential problems are solved.

Nutty. 10x more energy flows under this 24/7 (currents), and like everyone says, sticking these where they'll surely get trashed (birds, brine, barnicles, boats, burglars, ...) and a long way from where they're needed makes no sense.