Ran across this article today...

"Solar-Powered

These may be the mowers of the future. Poulan/Weed Eater introduced the first solar-powered robotic mower. It wanders around the yard by itself -- you don't have to touch it. Small razor-blade-type cutters clip the grass a little at a time. A wire, placed around the perimeter of the yard or flower beds, keeps the robotic mower within the bounds of the lawn. The unit clips grass all day long. If it hits an obstruction, such as a fence post or sprinkler, it stops, backs up, then goes forward again in another direction. Still, it requires level areas that include a minimum of obstructions. At $2,000, this mower is perhaps more a political statement than a practical way to keep your lawn trimmed.

Solar Power International offers a walk-behind solar-electric mower. The manufacturer claims that eight hours of direct sunlight charges the 12-volt lead-acid battery enough to cut grass for nearly two hours with the power of a four-horsepower gasoline mower. An optional charger you can plug in is also available. Cutting width is 21 inches, and cost is about $900."