Abstract: The general concept of smart load (SL) was originally introduced to provide practical implementation in grid power—frequency support applications, which belongs to demand respond (DR) technology. In this paper, a specific feature of SL which is composed of a SL controller and a linear load is introduced, after that, a comprehensive discussion on the application of SL for voltage stabilization and energy storage capacity reduction in an isolated microgrid is presented. The key component of this novel SL is the controller which is operated as a series reactive power compensator (RPC), unlike the traditional reactive power compensation technologies, it offers not only reactive power compensation but also active power variation in the linear load. To achieve this, an input voltage control and an input current control are introduced to respectively regulate the SL voltage and current. Detailed mathematical derivations of the proposed control paradigm are provided. Results validate the effectiveness of adopting this SL for a isolated microgrid with renewable energy source and energy storage system.