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< prev - next > Energy energy for rural communities (Printable PDF)
Energy for rural communities
Practical Action
voltage, which is acceptable for high voltage (HV) distribution systems but not
suitable for low-voltage systems. The main advantage is in the cost benefits
associated with the reduction of the number of wire required.
Three-phase low voltage lines
Three-phase wiring is relatively expensive for low voltage distribution that can use
single-phase options.
Single-phase low voltage lines with wire return
There is a cost benefit in reducing the number of wire associated with single-phase
systems compared to three-phase. The disadvantage of single-phase systems is that
the power delivery is not as smooth as a three-phase system, which can affect the
performance of electrical devices.
Single wire earth return (SWER)
A single-phase supply using the earth as the return reduces the costs even further by
eliminating the return wire. The system was developed in New Zealand in the 1920s
for rural energy supply.
In practice, a combination of transmission lines may be used depending on the size of the
distribution grid in question. From the power house there could be a three-phase high-tension
power line to minimise power losses, which can then be stepped to a lower voltage single-
phase lines for local distribution. In most mini-grid systems the distance of the supply lines
will only be a few kilometres. By comparison, national grid extensions to rural areas requires
much longer lines resulting in the need to upgrade the system to avoid excessive transmission
Distribution lines need to be supported off the ground at a height that means they will not
interfere with people’s activities or transport, and will not be dangerous. The poles have
certain requirements in terms of their size and strength, to counter wind conditions. In mini-
grid systems the distribution poles can be a significant cost of the overall project.
In the home
Special approaches are required for low-cost
electrification in the home if connections are to be
economic. In subsistence farming communities, the
average household expenditure on electricity can be less
than $1 per month.
The electricity consumption of low-income households
is often just a few tens of kilowatt hours (kWh) per
month. The main problems faced by low-income
households in obtaining an electricity supply are high
initial connection charges and high costs of house-
With appropriate techniques, houses can be connected
safely and with fewer dangers than those associated
with the use of kerosene and candles. The dangers from
electricity supply can be kept to a minimum by using
earth-leakage circuit-breakers, flexible wiring systems,
education, and regular safety checks. The high costs
faced by new consumers can be reduced through the
careful application of appropriate technologies such as
prefabricated house-wiring systems, e.g. wiring
harnesses and ready boards.
Figure 3: Mr. Vimalasene installing a
low energy bulb in his house in Sri
Lanka. Photo credit Practical Action / Zul
Load limited supply
Load limiters have been successful in reducing the connection cost and the operating cost of
electricity supply. The basic principle is to limit the current to a pre-prescribed maximum. If