Solar power may not yet be up to the task of powering mass transit vehicles, but it can do a fine job of powering mass transit stations. The Stillwell Avenue subway stop in Brooklyn has become New York City's first solar-powered train station, with over 76,000 square feet of thin-film PV generating 250,000 kWh a year.

The picture at Renewable Energy Access demonstrates what a large-scale building-integrated photovoltaic (BIPV) system looks like. Interestingly, they don't completely block light transmission -- about 20-25% of the light gets through, reducing the need for artificial daytime lighting.