The up to 400VDC power solutions feeding the power interface to ICT/telecom equipment as defined by ITU-T [ITU-T L.1200 series], are well adapted to straight forward use of renewable energy or distributed power sources through new simple DC nano or micro grids, This Recommendation defines the coupling of local or remote renewable energy into an up to 400VDC power system without reducing DC performances defined in [ITU-T L.1202] mainly for efficiency and reliability. The main advantages are saving of fossil fuel (as a source of primary energy consumption), reduction of GHG emission and increase of resilience. Additional site interconnection by DC grid can even bring more optimization. One other big benefit is that compared to AC, on 400VDC there is no synchronization required between the various inputs, which keeps the architecture simple.