Thank you so much sam, i am interested in solar energy and coming to grades i am having a grade between 2.5 to 3 is it real difficult for me to get a Ph.D in germany?

Hi everyone, I completed my Bachelors of Engineering and Masters with Electronics and communication background, I am very much interested in renewable energy, and i want to do my research accordingly. Please help me to know
1) whether i can do my Ph.D on renewable energy?
2) If at all I can, please let me know on which discipline i have to concentrate on.