Up on the dam, almost everything that looks like a problem becomes an advantage.
The plant sits above the fog line, in thin, clear air that lets far more sunlight through.
The higher you go, the stronger and cleaner the sunlight becomes.
Cold actually helps, because solar panels work more efficiently when they are not baking in heat.
And then there is the snow, which acts like a giant mirror, bouncing extra light up onto the panels from below.
Scientists call it the albedo effect, and it can lift a mountain plant’s output well beyond anything possible in the valley.
A test site at a similar height recorded yearly output far above a typical Swiss plant.
Honestly, I think it wouldn’t be a problem in any dam. I’m sure they made all the required studies but dams are so thick and made to withstand such great forces that a couple of solar panels bolted on would be negligible. I bet 10cm of water rise would be a way bigger load
Especially considering anything attracted to the dam is going to add a vertical force that could do more to help with the lateral force from the water than it would do to bring the dam closer to collapse, though probably does closer to nothing to the overall physics of the dam.
All those bolts are entry points for water if not thought through.