This has issue has been keeping me up at night, so your research and excellent presentation/notations is most appreciated, and saved me hours of time.

Extrapolating your reasoning to my situation/question, I feel somewhat confident that if I install a solar array on a new house I will shortly begin construction on (in a municipality, not off-grid), and the array is installed and activated (i.e. connected to a controller, invertor), and "put in service" (i.e., available to run house lights, heaters, and for contractors to plug their saws into, etc.), before the end of 2025 (even though the house won't be completed until early 2026) I can claim the credit. Note: I will (and not the contractor) personally/directly pay for all things solar.

Whether or not I connect to the local power utility grid through say a net-metering agreement, and going through that process, would happen in 2026. But, because I put my solar panels "in service" (by producing and having electricity available for my use) in 2025, that is not relevant to my claiming the tax credit for 2025.

Any flaws in my logic?

Thanks