Wanna know how the inventing appliances that work using solar power field is now existing? are there any specialization course 4 for this ?

Hi. Am going to do my mechanical engineering.I really wanna do some business. i think the field related to solar energy has a lot of room for development (inventing things that work on solar energy).Is there any specialization course for this ? i could study those thing side by with my mech syllabus