Remove husks and silks from corn. Holding ears in a large bowl, slice off kernels (to yield about 10 cups). When slicing corn from cobs, work in a deep bowl to catch the kernels and any juices. In two batches, puree kernels and accumulated juices with a total of 2 cups water until chunky.
In a large saucepan over medium-high heat, cook pureed corn, butter, 4 cups water, and salt until butter is melted and soup is heated through, 5 minutes.
Serve hot, garnished with tortilla chips, lime wedges, and sliced scallions, as desired.
Let cool, then freeze in individual servings; reheat over medium-low (or in microwave).