An Italian professor worked out a floating solar system on water, see more from the link.
http://news.yahoo.com/italian-engineer-invents-floating-solar-panels-155245586.html;_ylt=Amotpedm0y2RQTWJqSwJKsbzUc0F;_ylu=X3oDMTE2MjFyZjd0BG1pdAMEcG9zAzEEc2VjA01lZGlhU2VhcmNoUmVzdWx0c0liWEhS;_ylv=3

The flat panels are winged by reflectors and sit on raft-like structures which are anchored to the lake bed with a pylon, with water cooling at the back of the module. So the efficiency is expected to be higher than conventional system. But it may cause other problems, like the growth of aquatic life, the impaction to the biology under the water surface. What do you think?

Hi Rikio, I think you are headed in the right direction. This sounds like you are not far off to something great. I will be following you. Good Luck!

@Andreas, I am interesting in the cost analysis of such a system, could you send me a copy of your study?

Thank you all for encouragement. Maybe I bring some confusion to you that this new product is not my baby, I got the news from internet, and want to have a discussion with you guys on this new system. Like Andreas, I have many boubts on the resisting capability to wind, ice and etc. I have heared of such a system, but did not know how it overcome the engineering issues. So raise a post here to get your ideas. Maybe some of my concerns are not necessary. It is just a process of learning.

Really sorry for the confusion and thanks to all of you again.

I do not think putting panels on water is worth the trouble:
- cooling gained will be leveraged by tilt lost
- servicing will be problematic
- aquatic growth will cover panels in no time - just look at boats left in water
- constant water contact will degrade panels through corrosion

Environmental impact is difficult to fully assess, but it will be significant and negative:
- change of water temperature
- change of evaporation
- change to water-air gas exchange
- change to feeding patterns for fish and fowl

Folks, how about if we run cool water in metallic pipes at the reverse ( bottom ) side of our PV panels, the water to be circulating in a mid -size container, ( say about 100 liters ), and a small DC water pump circulating the water.
Will this have any impact in cooling the PV panels during summer season ?
At my pace during summers temperatures go as high as 50 C.

Please comment / advise.

@Omar, I saw several attempts to build such panels. Typical result is that if you can't utilize low grade heat energy (warm water) then the whole exercise become cost prohibitive. To produce more energy by cooling the panel you have to spend energy pumping water and, possibly, cooling water.

@Federico, whatever these projects gain in short term efficiency, they will lose in long term maintenance: just imagine manual washing all this glass and mirrors from various organics.

@Anatoli : pls comment, if we install an outdoor DC based fan say with diameter of 18 to 24 inches, and install a small low pressure Water Mist system. This fan be blowing cool air on the panels. In this system, we will not be needing any cooling system, and the temperature of panels is lowered through evaporative cooling. What do u say about such a setup ?

@Omar: I'd say that such fan may be not a cost effective solution.
Let's do the math.
Very generous assumptions:
- panels with STC capacity of 250Wp, 14% efficiency, 0.5% per degree temp degradation
- 1 fan will cover with mist 5 panel with 1250Wp total and decrease their temperature by 25C
At 50C on panel production loss will be 1250*14%*(50-20)*0.5%=26.25W
Fan will bring this loss down 1250*14%*(50-20-25)*0.5%=4.4W and create a production gain of 26.25-4.4=21.9W
Forgetting uneven cooling of panels, loss of irradiation due to mist, power consumption by mist generator, costs of fan, need for water supply and its cost you will only have 22W to run your fan and enjoy the panel efficiency gain. I do not see a 20W fan cooling 5 panels.