There are many ways to transitionally contribute to green energy but why should you build it with a smart contract? Like what are the actual benefits or the urgency of tokenizing green energy/solar stations? Personally, nowadays it seems like smart contracts are just some another buzzword like the word blockchain whose idealized to solve many real words problems magically.

Currently, I think there is nothing you can do to legitimize check the obligation solely based on a smart contract. You still need a real physical entity as an intermediary to do the job.