We performed an energy-saving retrofit on the lighting system for a manufacturing company in Dongguan. The original power supply had low conversion efficiency and high energy consumption. We replaced it with an ultra-high-efficiency series power supply—the 12V model achieves 92% efficiency, and the 24V model reaches 94% efficiency. This reduced overall lighting energy consumption by 30%. Furthermore, the power supply's compact size and ease of installation significantly improved integration. Not only did the customer achieve significant savings on electricity bills, but they also achieved local Green Factory certification.