Natural gas and power operators in Texas were blitzed by arctic temperatures in February. THOMAS SHEA/AFP via Getty Images A watchdog for Texas' power-grid operator said it overcharged as millions went powerless. The Electric Reliability Council of Texas is not federally regulated. The report said power prices were set at $9,000 per megawatt per hour, the highest price possible. Visit the Business section of Insider for more stories. Potomac Economics, an independent market monitor for Texas' Public Utility Commission said that the state's power-grid operator massively overcharged residents as the state was rocked by a deep freeze and power grid failures in late February.The overcharges came in at a total of $16 billion, according to the filing.