Two good things solar panels over water reservoirs are:
1.) It prevents land-use conflicts.
2.) Due to the temperature-regulating effect of water and little shadowing, it also improves PV efficiency
Here's this assuming you need it in a form of a sentence:
In general, putting solar panels on water bodies prevents land-use conflicts. It also improves PV efficiency due to the temperature-regulating effect of water and little shadowing, while the water body benefits from reduced algae development and evaporation.
hope this helps!:))