What are the most useful graduate degrees for success in the energy field (specifically renewables)?

I just learned that my company has a tuition reimbursement for any graduate degree related to the job. I’m young and have free time, so I’m interested in taking advantage of this program but I’m a bit directionless.

I have a B.S. in chemical engineering, and I have worked as a controls engineer on renewable projects for 2 years. The most obvious degree to continue my career is a Masters’ of Electrical Engineering. Is there anything else I should consider?

Obviously, I have a lot more research to do before making any decisions.