What if you could simply pay a weekly fee for your power usage based on consumption? Pretty much like how most people get their electricity.
It would be rather unfitting for the setting. We pay for our power, because we have all that infrastructure in place to transport power.
Rimworlds are defined by a lack of that infrastructure. They are in a wierd spot where we have modern generation technology, but not modern transportation infrastructure.
But there might be a simple way to mod it:
1 Generator that has a incredibly high max output - and uses Silver as fuel.
You are "paying" Silver to have the power generation you want in your colony.