Do not ask me how long I've been "building" my first battery.
Of course, it might make you feel better. And me worse!
I've had my cells for 2 years....
That's the case most times, but I've run into a couple exceptions.
1) Crucial used to require the original packaging for their 2.5" SSDs because they put some information on the package and not on the SSD itself. If you didn't have the box, no warranty for you, because you don't have that...
My primary grid tied install was all permitted but no inspector showed up to look at it. I just don't think my AHJ cares all that much. Sure hope IRS only cares about the receipt and not the AHJ sign-off!