Apparently they landed with more battery charge than when they took off. Perpetual motion, if you can stay awake!
Edit: I just read this on the NY Times
With all of those solar cells and batteries, you would have thought he could have charged is iPod.“His only complaints involve little things like a slightly sore back as well as a 10-hour period during which it was minus 20 degrees Celsius in the cockpit.†“That made his drinking water system freeze up and worse of all his iPod batteries die.â€