Simon Bransfield-Garth was standing awestruck in the middle of a dark village in rural Zimbabwe one night last year. Earlier that day, his company, Azuri Technologies, had installed one of its low-cost, pay-as-you-go solar panels on a test house in the village. Now he was seeing the result. "The entire place was completely dark except for one bright house in the middle of it," he says. "That's when I realized, 'OK. This makes a difference.' "

Azuri has distributed 7,000 Indigo solar systems across sub-Saharan Africa and hopes to have 150,000 systems in place by the end of this year. The grand vision, says Bransfield-Garth, is to bring electricity to everyone in Africa.

Originally, Azuri was nothing more than a marketing project for Bransfield-Garth's other company, Eight19, which is developing lightweight, affordable solar panels. Because those panels won't enter production for a few years, the Eight19 team members decided to first navigate the complexities of working in sub-Saharan Africa using traditional solar panels. They quickly saw the scale of the opportunity and the impact it could have and spun off Azuri.

Plenty of people have tried and failed to bring sustainable solar power to Africa. The problem is, although a $50 solar panel may sound cheap to a westerner, it's a pricey proposition for someone living on $3 a day. Instead, people rely on kerosene lamps, which are pricier over time and potentially hazardous but affordable on a daily basis.

"By giving them light, Azuri is givingtime back to communities. When it does that, it allows economies to grow." --Scott Harrison

So Azuri took a new approach, establishing the pay-as-you-go model. Rather than paying for the solar system up front, customers buy scratch cards costing $1 to $1.50 a week, depending on location, from local resellers. Then, they text Azuri the codes on the cards to activate the system, which comes with a solar panel and battery pack, two overhead lights, and a mobile-phone charger. It can be paid off after 18 months of steady payments. After that, customers can pay a service fee of 50 cents a week or upgrade to a system that generates enough energy to power four lights, a phone, and a radio for $2 a week.

Azuri has earned a designation as a Nobel Sustainability Supported Clean Tech company. This year, it was named one of the World Economic Forum's Technology Pioneers. As altruistic as the company is, it's also a decidedly for-profit venture. So far, Azuri's revenue has not been substantial, but Bransfield-Garth believes a self-sustaining revenue stream is the only way to scale. And, for him, providing basic power is just the beginning. "It's the first step in a process of enabling rural communities to have access to the technology we've got," he says. "By providing people with access to knowledge, to media, to the Internet on their phones, it affects what they can accomplish."