Black start / bootstrap bus operation especially with power-line networking

[jlgula]

The issue is how to start a bus that uses power-line networking when there is no power for the devices to begin operation and communications.

ISO 21780 requires that the control and communications circuits operate down to 24V. I suggest that a 48V bus needs a bootstrap mode in which sources can apply a limited current at less than 30V without receiving a communications signal from some master control. This would allow a source like a PV system to supply enough power to initiate communications and normal operations. The designated bootstrap current should be low enough that almost any source can provide enough power for the entire bus without requiring any kind of droop control in the event that multiple sources come on-line before normal operation is established.