The comment you complained privately about was mine. And since you're still snarking about it, let's run the numbers:

US energy consumption, 2013: 25,451TWh. Let's crack that down into hours, rather than spreading it across the year and we're at 2.9 terawatts constant capacity.

Average solar energy per square foot, 2015: 13.8W

What we wanna use for daylight? They've got about 10 hours right now, and it's a couple months past solstice. Six months from now they've got 14 hours. Let's put the duty cycle at half a day. That puts a solar panel at 7 watts per square foot.

Cracking it down to square miles to get rid of some of the decimality (2.8e7 feet per square mile; 1,000,000 watts per megawatt) and we're at 27.88 megawatts per square mile.

2.9 terawatts/27.88 megawatts = 10,401 square miles.

There's some dickering in there - solar panels weren't quite as efficient in 1995 but power usage wasn't quite as high. By the way: the Nevada Test & Training Range is 4500 square miles. This is land that we use to drop explosives on, primarily, and it's not quite halfway to your disingenuous square.

I read Mackay's book, by the way. Or part of it, anyway. He's condescending. And my flippant comment was exactly that - flippant. No one is advocating dropping ten thousand square miles of solar panels in the middle of Nevada ("How do you rinse dust off the panels, in the desert? "). The whole point of the argument is that yes, typo, 200 square miles of solar panels feeds a state.

And yes. 200 square miles of solar panels is a bajillion dollars. And yes. there are probably better ways to do sustainable energy. And yes. There are formidable challenges. But snarking about it instructs no one.

And snarking about it behind my back is cowardly.