They are calculated individually, but unfortunately the Solar Credit is applied first, and the electric vehicle credit does not carry over.
That means that if the total of your credits are more than your total income tax on your tax return (Line 47 of your Form 1040), the excess would be lost (unless you still have unused Solar Credit, then that unused amount would carry over but the electric vehicle credit would be lost).
In the event you think your total credits will be more than your total income tax, if you can 'create' more income by converting any Traditional IRAs to Roth IRAs, that would be beneficial.
