(introduction...)

GTZ has acquired most of its practical experience with three PV technology options for rural electricity supply:

- Central-station village power-supply systems
- Battery-charging stations
- Solar home systems (SHS).

Of the three, the central-station approach is most similar to the conventional option of seeing up isolated grids fed by diesel-powered generators to serve large villages. Thus, it also competes economically with diesel-based systems.

Battery-charging stations, by contrast, are decentralized facilities, many of whose customers must haul their automotive batteries considerable distances to be recharged. Transporting the batteries is inconvenient, time-consuming and expensive, and each time they are recharged they provide only a limited amount of electric power for lighting and to run home entertainment equipment.

The advantage that solar-powered battery-charging stations have over grid-fed or diesel-based facilities Is that they can be installed closer to users. In many cases, the batteries need only be transported a few hundred yards. Moreover, with battery-charging stations the users do not have to buy an expensive solar panel, as they do with SHS. Indeed, the only investment that is required is the outlay to purchase a 12-volt battery, which even the poorest rural dwellers can nearly always afford.

The most decentralized approach is that involving solar home systems. SHS provide only a basic electricity supply for lighting and the operation of cassette players, etc. Thus, the small PV systems hardly ever provide all of the services supplied by a conventional power supply system. Accordingly, they do not compete economically with the classic electrification options, but rather with lighting oil, kerosene, candles, dry-cell batteries and car batteries used in non-automotive applications.

In its projects, GTZ has acquired experience with all three of the options discussed above, and we are therefore in a position to assess their relative advantages and drawbacks.