I think "green" is not the right moniker here; "renewable" covers it better I think. With (with my limited knowledge, naive opinion) solar panels and wind farms having less of an impact than hydro dams.
Judging only on 'renewable' the ecological impact of a hydro-electric dam doesn't matter. The energy extracted here is renewable. Because rain will keep falling and thus the reservoir will keep being filled.
The fact that it damages an ecosystem does not count there. Moreover, the fact that dams damage an ecosystem have very little bearing on the global-warming effects of dams.
Whilst I do not want to say that ecological damage is not important, I think it is an issue that 'green' and 'ecological' have dual meanings. The current main usage being "Does not cause greenhouse gasses" with a less used original meaning of "Is good for the environment". This causes a lot of friction between people who use the same words but care differently about environmental impact beyond global warming.
It used to be that caring about the environment was a fringe movement in so far as getting political change. Global warming has gotten 'being green' on the political agenda. But it sometimes feels like some of the more extremist green ideas have snuck into the greater public discourse under the guise of being 'green'.
