Solar developers and investors may have to brace for solar panel costs to start rising after a 30-percent plunge last year. The period of ultra-cheap solar panels is over, according to the president of one of China’s largest solar panel manufacturers. The party is definitely over, Eric Luo, president of China’s GCL System Integration Technology, told Reuters this week, commenting on the super-cheap solar components on the global market. According to the Chinese manager, solar panel prices have already stabilized and are expected to…