Steve Katsaros, inventor of the Nokero solar-powered lightbulb, recently told CNN that he decided to sell his bulbs rather than give them away, even though it runs counter to the traditional model of aid to the developing world.

"Many NGOs say it's making money on the back of the poor, but I love to make money on the back of the poor," says Paul Polak, author of Out of Poverty, the 2008 book that inspired Katsaros.

He was probably at least half-joking, but he's got a real point: giving stuff away doesn't actually help local economies, whereas selling things cheaply can allow local entrepreneurs to create their own businesses distributing and servicing items that can be maintained by villagers themselves.

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So it is with the Nokero solar-powered lightbulb, which consists of a straightforward solar panel, rechargeable batteries and energy-efficient LED bulbs. Nokero already sells "business in a box" kits in Kenya and Tanzania, including 144 bulbs and flyers for small entrepreneurs to distribute.