SociaLite Lighting Systems

Engineering for the Middle of Nowhere

Technology


Overview


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We set out to design a solar powered lighting system for assembly, installation, operation, maintenance and repair by the inhabitants of impoverished communities; a solution to accommodate their culture, environment, and materials available at the point of use. We dreamed of a truly technological, financial and operational self-sustaining system—accessible from income and location perspectives, maintainable from locale, cost and complexity, durable from considerations of culture, climate and usage—a light source for those inhabiting regions devoid of the infrastructure—expensive items, such as photovoltaic panels, shared to reduce system cost.

Working with our advisors and community groups in which the end-user assumes responsibility for system implementation comes the promise of self-sustainability—an approach fundamentally different to many organizations. Characteristics common to many of these ventures include light sources developed and manufactured far from the place of use; local infrastructures for the maintenance and repair of these systems that do not exist and cannot be created; equipment often sold at less than cost price with subsidies from unsustainable sources; systems that are otherwise unaffordable to those for whom they are intended—the extreme poor.

Our prototype system has evolved into a more versatile community micro-grid supplied as a self-contained kit—a lighting system in a suitcase that includes the necessary tools, instructions in local languages, lantern and micro-grid components, audio amplifier and pico projector. Add locally sourced lantern housing materials and batteries to provide a complete system ready for delivery—on a pick up truck, a bicycle or someone’s head—a functional manufacturing and supply chain.
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The Lantern

Initial designs for the circuitry were simple, comprehendible by those with a high school diploma, but inefficient with separate circuitry for the LED and battery charging functions. A microprocessor gave us a single, firmware field upgradable, board with required functionality yielding a lantern that works indefinitely in the deep bush. Through hole circuitry provides a board that can be assembled by those unfamiliar with a transistor or a LED enabling the end-user to be more directly connected to the technology, through self-assembly and repair. Powered by 4.5 Ah, 6V lead acid batteries, the lanterns run at full power for about 40 hrs (reduced power for about 120 hrs) so requiring a weekly recharge and enabling each outlet to support up to 7 lanterns.

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A variety of designs using bamboo, cans and gourds for the housing body ended with undergraduate students in Ghana and Rwanda independently employing a robust, plastic hair relaxer container to host the battery and circuit. Two bicycle spokes connected this base to a translucent bottle for light diffusion with a third spoke used for the handle—this design proving to be very effective. Molded plastic housings are expensive and fragile, and, once broken, irreparable. Always room for improvement, the overall lantern design continues to prove very robust from electrical and mechanical perspectives in some of the harshest operating environments imaginable. We are in the process of migrating to a surface mount technology for the LED drive and battery charging circuits as through hole components start to become obsolete.

Operation

Value Chain

Our current model is the provision of a lighting service in which users pay for use of the lanterns—not precluding an entrepreneur purchasing a complete system outright. Choosing to work with the most marginalized communities on the planet—those who now fall out of the remit of the large philanthropic and UN agencies, the forgotten communities of 2020, poses a challenge. Someone, somewhere has to purchase the equipment and the end-user has to pay the real price—with a subsidized or zero rate of interest. Upon introduction of SociaLite to a community, users pay a deposit (≈ 5USD) on acquisition of a lantern to join a "lighting club", followed by a monthly charging fee (≈ 2USD)—both adjusted to match community assets. Extra income is derived from the per use payment for cell phone charging and use of the audiovisual entertainment facilities—both streams paying off the capital cost of system installation, operation (including lantern battery replacement and recycling) and maintenance—the excess being used to purchase the equipment for succeeding communities.

With bulk purchase, the cost of a lantern approaches 10USD—allowing compensation for those who assemble, install and operate the system. The cost of PV panels has dropped to <1USD/watt peak for rigid panels and to approximately 1.40USD/watt peak (incl. shipping) for lightweight, flexible CIGS panels from Switzerland; robust lead acid batteries (75Ah) run to about 150USD in country. With audiovisual facilities, the cost of a typical installed micro-grid is approximately 1500USD.
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Micro Grid

Isolated communities comprising more than about 50 households have their own micro-grid with or without the optional audiovisual entertainment system. New in 2020 is the implementation of a mobile charging and entertainment system, a micro-grid on wheels to serve the needs of smaller communities for whom it is currently uneconomic to install a dedicated system. The community members chosen to run the charging station are responsible for collecting the weekly charging fee for the lanterns, the per use fee for charging phones and renting the entertainment system from which they receive a proportion of the income.