Thanks for sharing your experiences!
I wonder, could the sensor not be manipulated to show more generated electricity than actually produced? That’s why usually you have a centralized database: one entity to confirm the transaction or, in this cas, the the size of the installation. For a decentralized system you would need to have some proof of work, or a proof of solar production here.
I just came across SolarCoin, but they also need a 3rd party (institution) to verify proof of work. And of course that party will maintain it’s own centralized database.