The problem Sunday solves

Sunday unlocks a novel type of crowdfunding for photovoltaic owners, where they finance their installations by offsetting future profits as interest to investors.

This approach provides an alternative for PV owners who are uncertain about the long-term performance of their systems and wish to mitigate operational risks. In turn, the funding model is well-suited to investors with a higher risk profile, particularly those bullish on energy prices, who seek potentially higher variable returns over time, tied directly to the installation’s real-world performance.

Challenges I ran into

I've struggled a bit with the exact composition of contracts. The goal from the start was not having to deploy much contracts with the additional projects that would need to be financed. ERC-1155 is quite a good fit in that regard as it allows to have multiple versions of the same token with their own metadata. I've also managed to use one Chainlink adapter contract that would support multiple vaults.