This isn't a billboard. It's a power plant.

Earlier this week, Pacific Gas & Electric began testing a solar-powered billboard in San Francisco that also functions as power plant plant. On a sunny day, the billboard generates as much as 3.4 kilowatts of energy, almost enough for the average American household of four. On cloudy days, the billboard generates about 2.5 kilowatts of energy.

PG&E's solar billboard is a first for the U.S., but not a first in the world, as both Canada and Africa already have them. Unlike Canada, however, PG&E's billboard actually pushes power into the electrical grid. The billboard does borrow electricity at night, but LED (light emitting diode) lights use less than a third of the energy that billboards with halophane lights.

The billboard is part of PG&E's new advertising campaign "We can do this", reflecting their commitment to the environment. The campaign was designed by advertising agency Venables Bell in San Francisco.