July 3, 2009 11:00 AM PDT
The huge wing boasts more than 12,000 solar panels. In creating the panels, the designers had to balance weight with efficiency. The energy soaked up by the panels serves to propel the plane. But those panels also charge the plane's lithium polymer batteries, allowing it to take flight at night. The pilots can count on at best only eight hours of sunlight per day, and the lower the sun sinks on the horizon, the less light there is to be captured by the panels.
When the Solar Impulse HB-SIA begins its first lengthy test flight throughout the day and night, the pilots must hope the batteries have enough energy to keep it in the air until the sun comes up the next morning to recharge the panels.
Caption by Lance Whitney
Photo by Solar Impulse/Le Truc
