VIVA LAS VEGAS: Ford unveils the Focus Electric. (Photo: Jim Motavalli) It's a cliché to start a story about auto-based solar with "here comes the sun," but, well, here comes the sun. Ford is teaming up with SunPower on a pretty cool idea - since electric cars aren't all that green if they charge off a dirty coal grid, the company is offering its Focus EV customers a chance to install a 2.5-kilowatt rooftop solar array that can produce 3,000 kilowatt hours of electricity annually, about what you'd need to drive 1,000 miles a month.

It’s called “Drive Green for Life,” which is probably better than calling it “Here Comes the Sun.” The idea is great, but the catch is the price: it’s “less than $10,000,” and that’s after the 30 percent federal tax credit and before local sales taxes.

Of course, you can also shop around and find a better solar deal — the availability of lower-cost systems is exploding, and costs are coming down all the time. Ford says an advantage of the SunPower system is that it offers less of a footprint on your roof, and includes a residential monitoring system that lets you track photovoltaic performance through an iPhone or on the Web.

Solar EV charging is starting to catch on. General Electric unveiled a huge 100-kilowatt array at one of its Connecticut offices, with enough power to charge 13 Chevy Volts a day. A company called EnvisionSolar is installing “solar trees” that provide shade as well as EV charging. Fast-growing SolarCity, which recently went national by setting up solar leasing operations on the East Coast as well as California, is now offering EV charging for $1,500 as part of the deal. According to CEO Lyndon Rive, “Electric cars are already among the cleanest-running vehicles on the road — charging them on solar makes them that much better.”

Did I mention that there’s an annual event called the World Solar Challenge in the Australian Outback, and a three-wheeled ultra-lightweight solar-powered EV made by a Dutch college is now in training for the October event — and claiming to be the world’s fastest solar-powered car? The sun can’t power regular cars — the panels on cars like the Fisker Karma and the Toyota Prius are there to provide some ventilation when the car is parked.

The Focus has been a long time coming, and will be a welcome addition to the stable of major manufacturer electric vehicles. But in 2011, only customers in New York and California will be able to buy a Focus Electric. That announcement created some confusion among those of us who thought it was rolling out to 19 markets, but Ford insisted the car isn’t being delayed — just strategically allocated. California is EV ground zero.

The other markets will have the car in the spring. Here’s the full launch list — is your city on it? Atlanta; Austin, Texas; Boston; Chicago; Denver; Detroit; Houston; Los Angeles; New York; Orlando, Fla.; Phoenix; Portland, Ore.; Raleigh/Durham, N.C.; Richmond, Va.; San Diego; San Francisco; Seattle; Tucson, Ariz.; and Washington, D.C.

Ford CEO Alan Mulally was on David Letterman's show last week with the Focus Electric, so let’s go to the videotape: