All utilities shall pay interest on any and all deposits held by the utility on behalf of a small business. The rate of interest to be paid on such deposits will be determined by the Commission.
     At the end of every year of service, if the deposit plus interest is not refunded to the small business the utility shall automatically refund the accrued interest on the deposit to the customer by crediting the small business’ account and so stating this credit clearly on the small business’ next regular bill.