Combine soy sauce, brown sugar, oil, ginger, and garlic powder in a 9x13-inch casserole. Mix until brown sugar completely dissolves into the mixture.
Place chicken wings in the dish and turn them over until they are all well coated. Cover the dish and refrigerate for at least 4 hours, turning the chicken again halfway through.
Preheat the oven to 350 degrees F (175 degrees C).
Bake chicken in the preheated oven, covered, for 45 minutes. Turn chicken wings and spoon sauce from the bottom of the pan over the tops of the wings. Cook, uncovered, for an additional 50 minutes.