[brk]

Because they sell more power back into the grid than they use up.

That doesn't make sense. The breakeven point for a solar panel is around 10 years (assuming you're using it solely for your own power generation purposes, that is how long it takes for the panel to "pay for itself" in offset electricity costs).

The charging stations are there to charge vehicles. To keep them breakeven on power (forget about land/rent/taxes/maintenance) they would need a field of solar panels.

Hardly seems like a logical approach.

My guess is more that they will sell "upgrades" to the vehicles, they mentioned the large touchscreen and upgradability in the article. Perhaps certain future software enhancements will be paid, in order to generate some residual revenues.

[w1ntermute]

Musk has a startup (SolarCity) that specifically deals with solar panels and is providing the panels for the Tesla supercharging stations, so he has deep knowledge of the field. He's clearly managed to make the numbers work out, or he wouldn't have made it free to charge.

[gknoy]

There are more ways to generate solar power than with solar panels. Presumably, they could invest in solar power plants. Heck, the highly illuminated towers of a solar power plant can be seen for miles, and could even be used for publicity: "Free power beacons on the road for Tesla cars..."

[sbierwagen]

Solar concentrating thermal plants only work in direct sunlight, and their mirrors don't like to be dirty. They're not terribly commercially attractive outside the Mojave.