I read this link. But, although it is an interesting idea, I was rather surprised that it offers significant advantages putting them on water. I would have naturally have assumed that there would be less advantage putting solar panels on open water when, for less cost I would assume, you could have the same total area of solar panels split up so that you have lots of separate panels on the sunniest south-slopping sides of the roofs of many houses. I would think that would be more cost effective than floating them on flat water because
1, you haven't got the cost of floats that stop them from sinking -all you have to do is bolt them firmly to the roof. Surely that cost less?
2, putting them on a south-sloping part of the roof would mean, in the Northern hemisphere, they would get more sun on average than if they are positioned horizontally. Therefore, with all else being equal, you get more average power out of them for the same costs.
For these reasons, I would have naturally thought it would be better to first fill up all the current wasted flat area on south-slopping roofs before considering floating some on water.
however, it says:
""Thanks to the cooling effect of water on PV panels, our systems produce more energy than land-based systems of a similar size,""
but why would lowering the temperature help make it produce more energy?
Perhaps when they get very hot, they become less energy efficient? But I assumed that they are built to be very heat resistant so it would surprise me if it really made that much of a difference.
but it does make an interesting point with:
"By lowering the water temperature and reducing the size of the water area exposed to air, floating solar panels can reduce water evaporation by up to 33 percent on natural lakes and ponds, and by up to 50 percent on man-made facilities..."
-not sure if that makes it generally better putting them there than putting them on south-sloping roofs. I cannot help but wonder, is water wasted by evaporation from these lakes really economically significant? I suppose that just depends. It may not be generally so for wet climates such as in the UK while I assume it is nearly always be significant for drier climates so it could be really great for dry climates!
Here in the UK, in resent years I have noticed we seem to more often get too much rain and flooding than we get too little rain and drought. So I wonder, couldn't reducing evaporation from lakes sometimes increase the flood risk? Could this be counterproductive for the UK?
But I have noticed that, taking account basic physics, the link appears to logically contradict itself!
Because it first says
"Thanks to the cooling effect of water on PV panels..."
but then it says:
""By lowering the water temperature..."
But if the water cools the panels, that means heat is being transferred from the panels to the water and therefore, surely, it would be heating the water, not cooling it!?
In addition, wouldn't the reduced evaporation mean less heat can escape via evaporation?
Am I missing something here?