Tom and Moderator, There is no reliable repellent that will keep yellow jackets, wasps or hornets out of shutters. They like the warmth and seculsion that shutters create to start their nest. If you see them starting a nest early in the spring use a garden hose behind the shutters. This may discourage them enought to leave.. otherwise wait for the females to be on the nest (usually during evening hours) and use Victor Non Poisonous Wasp spray. It is not a freeze but it will not stain the siding like most Wasp freezes.
I personally use a garden duster with Sevin dust. If you lightly dust behind all the shutters in the early spring before activity starts you may be able to kill most female wasps who will start a nest.
Bill Kolbe, B.C.E. Techincal & Training Manager Western Pest Services 1-800-544-2847