Subject: If the whole USA was covered in solar panels....

I read some where that if the USA was covered in solar panels, the overall 
energy collected in one day could power the nation for hundreds of days.
Approximatly how long would one day's worth of sun light supply the USA?

I know that the USA has 9,158,960 sq km of land, and I know that area would 
collect 9,158,960,000 watts (9.15896 Giga-watts) of energy. I also know that 
solar cells, now-a-days, are 15-to-27 percent efficient (on average). With that 
energy loss, that are would collect about 2,289,740,000 watts.
How much energy does the USA use each day?

To produce enough energy for the nation, how much space would needed to collect 
solar energy?

Re: If the whole USA was covered in solar panels....