Bi-directional DC to DC voltage convertors typically convert a lower DC voltage (i.e. 12-48V) into a higher one (i.e. 100-400V) and vice-versa, at high (+95%) efficiency. These devices could be used in a decentralized grid system to allow for efficient transfer of energy over longer distances and to provide isolation.
Several modules exist with this functionality, most of which find their typical usage in the electrical automobile industry for applications like regenerative breaking.
Vicor’s BCM chips