  The future smart grid is envisioned as a network of interconnected microgrids
(MGs) - small-scale local power networks comprising generators, storage
capacities and loads. MGs bring unprecedented modularity, efficiency,
sustainability, and resilience to the power grid as a whole. Due to the high
share of renewable generation, MGs require innovative concepts for control and
optimization, giving rise to a novel class of smart energy applications, in
which communications represent an integral part. In this paper, we review power
talk, a communication technique specifically developed for direct current MGs,
which exploits the communication potential residing within the MG power
equipment. Depending on the smart energy application, power talk can be used
either as a primary communication enabler, or an auxiliary communication system
that provides resilient and secure operation. The key advantage of power talk
is that it derives its availability, reliability, and security from the very MG
elements, outmatching standard, off-the shelf communication solutions.
