

I don’t want to go into a big long thesis so I’ll try to summize.
America, now firmly cemented in its boarders, fully federalised and with a wealth of natural resources and ballooning population was becoming a big power by the start of the 20th century and American politicians were putting in considerable effort into undermining the big European powers, but especially Britain.
The British empire being so spread out made it hard to defend and control. So with Britain and it’s colonies fighting on every front for the whole length of the war Britain lost many colonial holdings in Asia.
Those colonies also paid a heavy price in the fighting and independent movements flourished after the war and Britain didn’t have the money or political will the fight them, so the empire dissolved.
America was able to use its war economy to massively ramp up its domestic manufacturing.
They were also able to use their position as financers and occupiers in Europe and Asia to extend considerable American influence to those regions. And also Latin America and the Caribbean. Giving American companies influence over much of the world without the obligations the British Empire had.
Educated guess:
To allow the supply chain to adjust so we don’t cause a sudden shortage skyrocketing the price of solar, making homes more expensive to build or delaying construction
A lot of new build are basically copy pastes of the same design, so companies have time to properly adjust designs for them and not just haphazardly slap them on to existing ones which could cause problems
Red tape and Bureaucracy. Updating laws and regulation takes time, then there’s risk assessments environmental planning, maybe adjustments to the grid layout on new estates.