Direct sunlight is enough to soften the glues in your acoustic guitar, which will weaken or destroy the joints and destroy it. Do not display your guitar anywhere that will be exposed to the sun even as the light moves across your room during the day. One of the most unsettling experiences I ever had when shopping for a guitar, a Taylor no less, was after playing a few, the owner of the music store came up with a guitar and said, "Here, try this one". When I grabbed the guitar, it was hot. This was a beautiful air-conditioned store! I asked him why it was hot and he said he just took it out of the window. He said he took turns with all the guitars putting them in the window. Needless to say I didn't buy a guitar there.
Also be careful if you perform outside on nice sunny days. Try to be in subdued light if
Also see Tip 114.