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Cellular & Satellite Phones

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Mobile cellular phones and mobile satellite phones provide voice telephony services in rural and remote areas. In some cases they also support short message service (SMS) and low-speed data transfer. Mobile phone services are increasingly becoming available and affordable options for communications in remote areas. Coverage from cell sites along intercity roads and highways often spills over to include rural towns and villages. Satellites’ large coverage areas make them one of the few feasible options for providing connectivity services in very remote, sparsely populated areas where terrestrial communications infrastructure is unaffordable. Fixed applications of cellular and mobile satellite services can be implemented when mobility is not a requirement.

Handheld cellular and satellite phones typically consume less than 5 W on average, requiring less than 120 Wh of energy per day, which is typically provided by internal batteries and/or external battery packs. Fixed cellular and fixed satellite phones may run on AC or DC. There is already a thriving trade in battery recharging services for cellular handsets in many off-grid areas. However, providing a separate renewable energy system to power a single wireless telephone may be an expensive route given the low energy requirements, as explained in the box below.

Powering Small Loads: Energy for Public Telephones

Power systems incorporating RE technologies can be very appropriate for powering small loads, such as telephones for public use. Soluz, Inc., a developer of rural energy delivery companies, has implemented several commercial approaches to powering cellular telephones with renewable energy, balancing technical and financial needs.
PV-powered Payphone in Guzman, Dominican Rep.
Click to enlarge

As part of its work to support microenterprise and expand productive applications of PV, Soluz installed a pilot PV-powered cellular payphone in a rural store in 2001. The store, already renting a PV system for lighting, radio, and television from Soluz's local subsidiary, received a separate, dedicated system for the telephone, with a 50 W PV module, battery, and controller.

The system operated smoothly for the three years it was piloted, but was not financially self-sustaining. Though at times well used, the payphone did not generate enough revenue to cover the cost of the dedicated power system. The system was oversized, able to produce much more energy than the phone needed, and as such was more expensive than necessary.

Low-power loads such as the cellular payphone can benefit from an alternate approach to energy supply. As additions to larger power systems like the store's, such loads can use existing batteries and controllers, requiring at most a small upgrade in power-system capacity. The incremental cost of adding a 10 W PV module, for example, is minor compared to the cost of a standalone 10 W PV system.

In small loads, as with larger ICT systems, efficiency can be important. The payphone piloted by Soluz consumed 50-100 Watt-hours per day, but could be designed to consume half that by turning it on for outgoing calls only. Many Soluz customers power standard portable cell phones for their own use with negligible energy from their household or business PV systems. Such phones can also be operated as businesses in underserved areas. For example, a Village Payphone program in Uganda, based on the Grameen Village Phone in Bangladesh, sells a micro-financed payphone business equipment package consisting of a mobile phone, antenna, solar panel and battery, cables, airtime cards, signage, and manuals for a total cost of US$256 (Ref).


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