I love this as a rapid prototype. As others have brought up, I’m curious how you’re dealing with sensor tampering.

One idea is to have a block generated every period with some arbitrary number of “cryptojoules” as the reward that is greater than the theoretical max of how many joules can be absorbed by the panels in your system during that period. You have an account that represents the sun itself and only that account is allowed to generate new blocks. Each solar panel account can request cryptojoules from the sun, but the sun will only accept the request depending on certain tweakable conditions using sensor data that are communicated to the sun account out of band. The sensors can still be tampered with, sure, but this would at least be a mechanism that could detect abuse (not unlike a spam filter). If the conditions are met and the sun account is satisfied that the sensors are working properly, the transfer goes through. Then the solar panel can transfer its cryptojoules on a daily basis to NASDAQ.

This proposal doesn’t address the possibility of an adversary forcefully adding nodes to mount a 51% attack, which is something all private blockchains are particularly susceptible to. Also, having a sun account that acts as a mint is maybe philosophically opposed to the whole point of blockchains, but then again, a private regulated network of solar panels isn’t exactly the kind of open market that Bitcoin was devised to foster.