TR8: The future of DC systems for the off-grid environment

Rural areas that are not connected to an electricity grid are nevertheless seeking to increase their use of electricity to support services such as healthcare, education, and entertainment, and for productive uses to increase incomes. Such increases in electricity use in rural communities—“ climbing the energy ladder”—require a step-change in electricity provision to currently off-grid households.

The supply of electricity through centralised generation and a long-distance grid generally uses
alternating current, or AC, for distribution to households and buildings. However, this report
demonstrates that many of the electrical technologies upon which appliances are based are
powered by direct current (DC) electricity.1 The technologies that supply electricity for off-grid settlements (in particular solar photovoltaic panels and batteries) often generate DC electricity as well. Micro-grids that integrate DC-native electricity supplies with DC distribution and DC-native electrical appliances may possess energy efficiency and cost advantages over the AC distribution systems used on the main grid today because of the lack of a need for energy conversion from AC to DC.

However, there are three barriers to the widespread adoption of integrated DC generation,
distribution, and appliance systems:
1. The local context will determine the design of the micro-grid, which will in turn determine
whether it is advantageous to have a DC or AC architecture.
2. The availability of DC appliances and electrical equipment lags far behind their AC
counterparts, and the capital costs are consequently larger.
3. The standards, regulation, and expertise for the design and installation of DC micro-
grids lags far behind that of comparable AC systems.

The proliferation of solar home systems and single appliances that contain their own PV power
supply, most commonly pico-solar lights, has the potential to drive an implementation of DC
devices at a mass scale. However, under the wrong conditions, they also have the potential to reduce impetus for the installation of larger DC micro-grids, as many are not currently standardised and are therefore less capable of easy integration in local DC grids.

1 Technologies that generate or run on DC electricity without
the need for converting the current to or from alternating current
are called ‘native DC’ technologies.

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