Will sun exposure damage my speakers?

YES!

Direct sunlight will "cook" foam and the plastic resins in the
fiberglass cones causing them to become embrittled which
ultimately leads to failure.

I'd keep the speakers out of direct sunlight.

Dr. Gregory Greenman
Physicist

yes... plan on using a heavy duty window tint.

If the position allows too much light and you don't have options or glass tint is not of your liking, you might consider adding a fabric cover to your speakers to preserve them. In other words if you leave to work early in the morning and get back early in the evening, your speakers will stay all day long getting the light exposure without you enjoying their look. The covers can be made of decor color matching fabric, perhaps your S. O. stays all day long in the house she can put the covers to lessen the visual obstrusive boxes in your den or living, so maybe you can have a win/win scenario and improve WAF. My 2 cents.
Regards
Luis

That is what I thought. I usually put the grills back on on sunny days. I guess I will continue to do so! Thanks again

Arthur

Yes,
Sun rays ultimately change all that is in their path.
With speakers it will bleach the cabinets, dry the wood, and also, affect the drivers, (surrounds) if exposed too much.
Sort of like the white rat tests. "If a rat consumes 12.5 Million gallons of X it causes cancer". Hell if he consumes anything in THAT quantity it will kill him.
Moderation, combined with some UV filtering will help.