How much power do solar photovoltaic systems produce per unit of land area? And does it matter: is it a constraint in the real world?

At Elon Musk’s glitzy launch of the Tesla PowerWall and PowerPack batteries, the Tesla CEO showed a map of the US, with a small square in the North-West corner of Texas marked in blue, and said that solar panels over that surface area would be enough to enable US electricity to go carbon-free.

Here’s a quick fact-check on that claim. (more…)