Despite General Motors vice chairman Robert Lutz having colorfully called global warming a "total crock of s***" earlier this year, the company has made itself a world leader in solar energy generation.GM announced this week that it is building the world's largest rooftop solar power station at its car assembly plant in Zaragoza, Spain. Turns out solar power in the automotive world isn't strictly for science projects and marketing campaigns anymore.

GM's solar installation in Zaragoza will generate about 12 megawatts of power at its highest output and cover about 2,000,000 square feet of roof with 85,000 solar panels, and could be online as soon as September.

The automaker already has two of the largest solar power installations in the United States on the roofs of its Rancho Cucamonga and Fontana, Calif., parts warehouses. Both are rated at 1 megawatt.

The Rancho Cucamonga solar panels provide about 50% of the electricity to that facility. The Fontana project generates about 1.3 million kilowatt-hours of electricity a year, which is about the amount needed to power 200 homes yearly.

The Zaragoza installation will generate about 15.1 million kwh of power annually, which is equivalent to the demand of 4,575 Spanish households.

The average household in America consumes 10,656 kilowatt-hours (kwh) per year, according to the Department of Energy. The average annual consumption in Spain is 3,300 kwh, according to a statement from GM.

You read that right -- we Americans consume about three times more power than Spaniards. But hey, we're working on it.

His statement on global warming notwithstanding, Bob Lutz is leading GM's Chevrolet Volt project. The hybrid plug-in Volt is rumored to be unveiled in September, to coincide with GM's 100th anniversary. Not a moment too soon, for the cash-strapped carmaker.