Solar-DC micro-grids for multi-storied building complexes in emerging nations

Abstract

Growing economies like India are likely to construct many homes and buildings over the next 15 years. Since availability of power in these countries is limited and power is expensive, large-scale decentralised solar PVs, with falling solar PV costs and minimal installation costs, are attractive. While DC power line provides considerable advantage for new homes and building complexes, a lot of work on standardisation of voltages, guidelines for wiring practices and making DC-powered appliances available still needs to be done. However, India took the lead, first focusing on off-grid homes. A 48V DC microgrid with a 125W solar PV and effective battery storage of 0.5kWh is now powering about 5,000 off-grid homes in India, resulting in huge energy and cost savings. Similar advantages apply to offices and multi-storied building complexes. This paper is a study of such pilot implementations and ecosystem development that made these building-owners adopt DC power lines. This paper discusses the architecture used for DC power in these buildings, use of combined 230V AC and 48V DC as well as combined 380V DC and 48V DC. It describes an ecosystem for DC appliances, test implementations in three types of buildings and some early results from such deployments.