Shred fresh zucchini in a food processor and pour out any excess liquid before adding to the batter, or defrost frozen shredded zucchini and bring to room temperature, pouring out any excess liquid from the freezer bag before adding to the mix.
Preheat oven to 350 degrees and grease a 9 x 13-inch baking pan. In a large bowl, combine sugar, flour, cocoa, salt and baking soda. Slowly alternate stirring in oil and shredded zucchini, mixing well. Stir in vanilla and chocolate chips, ensuring wet and dry ingredients are fully incorporated before pouring batter into prepared pan. Bake for 30-35 minutes, until a toothpick comes out clean and the brownies are set. Cool before cutting with a serrated knife and serving.