NRG Energy, Inc. (NYSE: NRG) and MGM Resorts International (NYSE: MGM) today announced the completed expansion of the nation's largest rooftop solar array. On the roof of the Mandalay Bay Convention Center, the expanded solar array has more than 26,000 photovoltaic panels and produces a combined 8.3 MW dc (6.5 MW ac) of electricity, a new national record for rooftop arrays. At full production, the system supplies 25% of the power demand of the entire Mandalay Bay Resort & Casino campus.