The Siemens Power Transmission and Distribution Group (PTD, Erlangen, Germany) is electrifying a hundred villages in Gabon, Africa, in a 20 million euro project ordered by the state energy ministry and scheduled for completion by the end of 2003.
Under this program, Siemens is installing maintenance-free decentralized power supply systems that each consist of a switchgear cubicle with inverter, battery charge regulator and lead-acid batteries supplied from solar collectors on the roof of the cubicle. These systems have been developed to provide power for medical stations, village schools, homes and street lighting. Typical uses in the country's remote villages, which are scattered hundreds of kilometers apart, include the refrigeration of lifesaving vaccines and the operation of interior and exterior lights, fans and even shortwave receivers and satellite phones.
The solar energy systems for village schools are designed for a peak power of 660 W and those for medical stations for 550 W while the systems provided for domestic and street lighting applications operate at 110 W. Medical stations and schools are supplied with alternating current at 220 V. The electricity is distributed via conventional surface-mounted wiring. The solar power systems for domestic use operate at 12 V dc using sockets safeguarded against polarity reversal. In this case, the steel cubicle containing the batteries — minus the inverter — is installed inside the hut, and the solar cells are mounted on a steel pole outside. The steel cubicles are of a hermetically sealed, vermin-proof design. An electronic circuit-breaker in the cubicle automatically reconnects the system following any brief short-circuit or overload. Keys are lodged with the village elder in case any of the cubicles need to be opened at some future date, for example to change the batteries after a six- to ten-year service life.
Siemens PTD is working with several small local companies in its role as system integrator. The decentralized power-supply systems are supplied from Germany as turnkey installations. Once on site, they simply have to be mounted on concrete strip foundations, connected to the electrical systems and commissioned for operation. The aim of bringing solar electricity to villages in Gabon is not just to raise living standards and improve communications in the country's 270,000 sq km (104,248 sq miles). Siemens PTD also hopes this scheme will make it possible to store and refrigerate vaccines and medicines in medical stations, helping to improve healthcare and reduce Gabon's high infant mortality rate (8.7%).
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