Solar energy technology took an important step this week as Swiss researchers prepared for the longest test flight ever undertaken by a solar-powered airplane.

The test flight began on Wednesday in Switzerland and was set to conclude Thursday at sunrise. The flight is important because it will focus on the batteries that will be needed to keep the solar plane aloft during its planned test flight around the world in 2012.

According to the team's website, the Solar Impulse plane is covered with more than 11,000 photovoltaic panels on a craft with a wingspan of about 200 feet. The craft is about 65 feet long and weighs less than two tons.

An Associated Press report added that before the flight around the world is attempted, researchers are also planning to attempt a crossing of the Atlantic Ocean.

If the project is successful, it could open up new opportunities for solar energy to be used in the transportation sector, while also contributing to the ongoing improvement in battery technologies that will be increasingly relied upon to keep solar energy plants producing power for a longer portion of the day.