How many solar panels would that be?

If I wanted to generate all of that electricity using solar PV panels instead of by saving it through conservation, what would that look like?

If you assume 2.5 kW is the average installation size and you can get 8 hours/day of power at that peak level. To generate 231 TWh of energy would take ~31.6 million buildings.

According to the US Census and Dept of Energy, there are about 124 million residential + commercial buildings in the US. That means you'd need an average installation of solar panels on ~26% of all buildings in the US.
That's 1 in 4.
That's a lot.

If you estimate the average install cost at ~$21.4k (assuming Jan 2010 prices and 50% of total installed cost is the module), then that is ~$676 billion.
That's a lot too.