An electronic engineer is related to renewable energy mainly in the fields of electricity. I would say wind energy and Photovoltaics.
Regarding the other questions:
1. The qualifications depends on the country and university. but i would say it would be great if you are interested in electronic systems and eletronic applications. You should be in love with the field you want to live 3/4 your lifetime in (My personal Motto).
2. Duties mainly involve design, research, studies, installation and comissioning of wind turbines, Photovoltaic cells...
3. Renewable energy is a very interesting topic. it is the topic of the near future. I work in renewable energy and i do know how wonderful work here is. As for electronics, I am not actually in this field, but i assume it is as interesting as mechanics.