Solar Panels were officially operational on January 2019, but we signed the contract in 2018.

[BBYPENNY]

Our Solar Panels were up and running in January 2019, but we signed the contract for installation in 2018.  Do we claim the Home Energy Credit for 2019 (which we prefer to do), since that was when everything was technically up and running; approved by the electric company as well?

[Critter]

the credit is taken in the year the solar system is operational no matter when the contract was signed.