Every person operating in the State an electric light or power business as a public utility, whose franchise does not provide for the payment to the county in which the public utility operates of a tax, or a tax of less than two and one-half per cent, based upon the gross receipts of such person from all electric light or power furnished to consumers during each calendar year, shall file with the director of finance of the county in which the public utility operates, within one month after the expiration of each calendar year, a detailed statement showing all gross receipts from all electric light or power furnished to consumers during the preceding calendar year. Such person shall, at the same time pay to the director of finance, for and on behalf of such county, in addition to any and all other payments required to be made by law, two and one-half per cent of the gross receipts; or, if such person’s franchise provides for a tax of less than two and one-half per cent of the gross proceeds, the difference between the tax required under such franchise and two and one-half per cent of the gross receipts, of such person from all electric light or power furnished to consumers during the preceding calendar year.