Power-over-fiber technology provides several advantages for harsh industrial application and can potentially be widely used in electric power system. In this paper, a reliable power-over-fiber system is presented, which is able to adjust the optical power automatically corresponding to the variance of the output load. An optic-electric feedback energy management scheme is designed and experimentally verified. The static and dynamic responses of the system towards load variances are further tested. The results show that the working status of the laser can be dynamically changed according to the output load, rather than maintaining the laser at the status of high-power output, which will potentially prolong the life and enhance the reliability of the system.