Innovative Direct-Current Microgrids to Solve India’s Power Woes – IEEE Spectrum article tells that a group at the Indian Institute of Technology (IIT) Madras in conjunction with industrial partners, relies on solar-powered direct-current (DC) microgrids. For homes not connected to the grid, a 125-watt microgrid can serve as the sole source of electricity. For connected households, the microgrid acts as a backup power supply to let lighting, fans, TV sets, and cellphone chargers continue operating even during brownouts (about 10 percent of the typical household load).
This microgrid relies on DC because PV panels and batteries as well as consumer electronics, LED lighting, and a growing range of appliances all work with direct current. In that way it is possible to avoid the losses that come with converting back and forth between AC and DC. This micrgrid system is entirely DC system that uses a 48-volt DC line.
The selection of 48V DC is somewhat on sweet spot of being high enough not to cause very high lossses on short distances, is still relatively safe and this voltage level is already quite widely used in many applications (telecom infrastructure, data centers, power over Ethernet, vehicles, industrial applications, phantom power in audio systems).
This 48V DC system is not the only DC microgrid system that is being researched. Schneider Electric has higher power DC micro grid uses array of solar panel connected in series to generate power at 230 V DC. This 230 V DC can be transmitted over distance of 1-2km similar to 230V, AC distribution line using a 2 core cable and supporting poles.The micro grid charge controller installed in each house steps down 230V, DC to 14V, DC which is used to charge the storage battery and power the energy efficient DC loads in house.
For some other DC distribution ideas being considered on other countries, read DC distribution and power electronics applications in Smart Grids document.