What about we make possibly even multiple types of reactors. Fission, Fusion, Antimatter, and etc..: I mean Anti-matter reactors could be the most expensive, but they're fuel efficient and generate lots of electricity, but if destroyed, they risk blowing up the entire vessel. Fission Reactors are the cheapest but you must despose of nuclear waste via through ejecting them into space, and aren't as bad when they explode. Fusion reactors could be the current ones that run on fusion cells full of hydrogen.
Also Solar Panels as Lafiel said, would be utterly ineffective, you'd need a lot because with how these ships are, they use a lot of energy.
(Of course remember, my opinions do not matter)
