Electric vehicle proponents cite the cars' zero tailpipe emissions and extremely efficient use of energy, while critics often point out how coal-fired power plants generate electricity used to charge electric cars. Today, San Francisco unveiled a solar-powered electric vehicle charging station to counter the critics' argument and highlight the fact that electricity can come from a variety of sources.
An organization called Charge Across Town secured a grant from the 11th Hour Project to set up three of the solar-powered charging stations in locations around San Francisco: The Stonestown Galleria Mall parking lot, the public parking lot at Embarcadero and Green Street and a City CarShare lot at 17th and Shotwell Streets. Electric car owners will be able to plug in for free Level 2 charging, which adds about 10 miles per hour.
The charging stations come from San Diego-based Envision Solar. Each self-contained station needs no connection to local utilities, drawing its entire power needs from its own array of solar panels.
Envision Solar CEO Desmond Wheatley told CNET that the solar panels are the most efficient available, with solar energy conversion in the "high teens." Each station generates 3.3 kilowatts of electricity and includes a lithium ion battery pack module that stores 22.5 kilowatt-hours of electricity. Wheatley said the amount of electricity generated by the stations per day was good for 100 electric vehicle miles.
The solar arrays on the stations follow the sun to maximize energy collection. Each station is self-contained, and sits on what Wheatley called a Ballast Traction Pad, a heavy plate that serves as the station's base and the parking spot for electric vehicles. Installation merely involves setting one of the stations down in a suitable area, with the Ballast Traction Pad providing enough weight to hold the entire station down in up to 120 mph winds.
Envision Solar sells the charging stations for $45,000 each, although Wheatley pointed out that government incentives can knock 30 percent off the price.
The San Francisco stations will be in place through 2015.