HORRY COUNTY, S.C. (WBTW) -- Santee Cooper is asking its governing board to approve a nearly 5% rate hike that the Moncks Corner-based utility says is necessary to keep pace with demand and invest in systemwide upgrades. The company also plans to roll out a new fee structure encouraging customers to use high-demand appliances during non-peak hours. "We need to invest in our system to ensure we continue to power a reliable and sustainable futur…