Thanks guys for your replies.
Believe it or not, I've already had 3 calc. courses, diffierential equations and I took linear algebra one summer. I've also had physics up to e&m and I've also had a circuits course. (I had a lot of IB and AP credits so I dove into some more challenging courses)...
I'm currently studying computer science, but I'm convinced solar engineering is where I'm supposed to be. I have some robotics courses coming up junior and senior year, but I would like to know what are some of the engineering courses I could take during the summer to prepare me for a graduate...