How to depreciate a solar power system on the roof of a home that is partially used for business?

I'm self-employed and run an engineering services company from my home office. I file a Schedule C and Form 8829. My business usage is 21%.

In 2025 I installed a grid-tied rooftop solar power system without battery storage and placed it in service in November. I'm unclear as to how to depreciate the business portion of this improvement.

Following the instructions for Form 8829 would depreciate it as 39-year property. That makes sense for Form 8829, but on the other hand, although the panels are bolted to my roof, my house works as a shelter just as well with or without them. They're a power plant that happens to reside on my roof, but my house doesn't need them to function as a house, so maybe treating the solar system as Section 1250 property isn't quite right.

To add more confusion, I know until 2025, there was a special carve out that solar was 5-year property. There are notes in the "what's new" section of the instructions for Form 4562 and Pub 946 that solar is no longer 5-year, but they do not say how many years it now is.