Budgeting solar is like chopping firewood for winter. You cut as much as you think you need. Do that again. Then the whole process again.

There are so many factors that can diminish the amount of power available at a particular location that the only reasonable thing to do is overbuild. Imagine a line of teslas at an upstate New York charging station. They cannot get to work without power. But it's raining. And it's winter. And it's 6am. And that treeline has grown a foot higher, pushing dawn back an hour. You cannot have too many panels.