Solar can only get cost competitive with coal when it exists as a supplemental power source. It cannot take over baseline supply due to intermittency so it can only serve to shave off daytime peaks.
Storage? Sure, but that costs money and shaves off efficiency. And if you want to go full solar you need to expand the farms so they can:
1. Cover all daytime demands.
2. Produce enough surplus to charge all the battery banks to cover the sunless hours.
3. Produce even more surplus because some days are cloudy.
The topaz solar farm, peak production 550MW, is 25km^2 in area. Average production estimate is 125 MW = 1,096 GWh/year.
A baseload power plant, classic numbers, are 1000MW, 90% uptime. So 900MW average.
To replace one of those, assuming perfecft efficiency battery storage, you need 180km^2 of solar panels that produce 4GW electric at peak. This also means that battery storage needs to be colocated unless you want to build a new grid too.
US total power consumption 2008: 4,401,698GWh. That's 4016 topaz solar farms, again ignoring efficiency losses.
This is 100400km^2.
That's 1/3 of the surface area of germany.
That's a circle with the radius 180km( or diameter360km )
That's you standing on top of the world tallest building and only seeing solar panel all the way to the horizon.
In fact YOU COULD STAND ON TOP OF A BUILDING IN THE CENTER THAT'S 2400 METERS TALL (3x Burj Khalifa) AND WOULD STILL ONLY SEE SOLAR PANELS ALL THE WAY TO THE HORIZON!!!!!!
In short: The solar future doesn't look as bright once you start to scale it.