Power electronic interfaces are vital to advanced, smarter, distributed grids and micro-grids and the capabilities and limitations of power devices are integral to this. This paper discusses existing and emerging applications of grid connected electronic interfaces that are enabled by Power Semiconductor Devices. The application focus will be on: (1) inverters, which are a key element of modern distributed and renewable energy systems; (2) solid-state transformers which hold great promise to reduce size and weight, while enhancing performance, compared to existing Grid transformers; (3) MV static transfer switches, which facilitate redundant power at the medium voltage level. Capabilities and tradeoffs between Power circuit topologies, available devices, and circuit techniques are presented. Existing and projected market opportunities are also presented, and motivation for future device development is outlined. Emerging transformative research using wide band gap devices in silicon-dominated power device applications, along with hybrid power switch configurations, will also be highlighted. The compelling requirement of advanced grids for both fast fault current limiting, fast voltage control, and possibly increased overload capability to enable the much heralded advances, are also shown to be completely dependent on devices, along with their cost effective application.