Your choice should depend on the program and language learning curve. While China and germany increasingly start teaching in English, it is not the norm.
Hi. There is no precise answer to this question since many factors go into deciding what might be "best" for someone. A good resource is AASHE's degree program database at https://hub.aashe.org/browse/types/academicprogram/.
The question should be reformulated as 'renewable energy' is a very broad field, and the list of Unis will be different for wind, solar, wave, etc. Moreover, what part of technology you are interested in? Taking wind as an example, some Unis are amazing in aerodynamics, others have strong track records with electrical generators, etc.