Photovoltaics and Energy Storage Integrated Flexible Direct Current Distribution Systems of Buildings: Definition, Technology Review, and Application

For a future carbon-neutral society, it is a great challenge to coordinate between the demand and supply sides of a power grid with high penetration of renewable energy sources.In this paper, a general power distribution system of buildings, namely, PEDF (photovoltaics, energy storage, direct current, flexibility), is proposed to provide an effective solution from the demand side.A PEDF system integrates distributed photovoltaics, energy storages (including traditional and virtual energy storage), and a direct current distribution system into a building to provide flexible services for the external power grid.System topology and control strategies at the grid, building, and device levels are introduced and analyzed.We select representative work about key technologies of the PEDF system in recent years, analyze research focuses, and summarize their major challenges & future opportunities.Then, we introduce three real application cases of the PEDF system.On-site measurement results demonstrate its feasibility and advantages.With the rapid growth of renewable power production and electric vehicles, the PEDF system is a potential and promising approach for largescale integration of renewable energy in a carbon-neutral future.