The Solar Impulse, an airplane traveling across the United States using only solar power, is in Phoenix today, after reaching Arizona from California Saturday. It took the plane about 20 hours to travel from Mountain View, Calif., near San Francisco.
The aircraft is capable of flying at night as well as in daytime; the plane had about 75 percent of its battery power remaining when it landed in Arizona.
Now solar power has had its problems in recent decades. For years, solar panels were too expensive to compete. More recently, as we heard earlier in the business news, solar panels got so cheap that manufacturers ran into trouble. But solar energy had a signal achievement in March, and that is our last word in business today.