Those that have their hearts set on shinning sunlight directly onto their Wii Sensor Bar are worried. Worried that they won't be able to play their Wii in the middle of Death Valley at high noon. And damn well they should be! But, Nintendo isn't worried and doesn't think there is anything to worry about. A company rep tells 1Up:

Our testing thus far shows no great risk of light interference when playing a game that relies on the pointer and sensor bar.

And there you have it. The Wii Sensor Bar ain't no vampire. Brian Ashcraft

Sensor Issue [1Up]