By Tanzanian standards, Nosim Noah is not poor. A tall, handsome woman with the angular features of her fellow Masai tribe members, Ms. Noah makes a good living selling women's and children's clothes. But despite their relative prosperity, up until late 2013, the family had no electricity. Now, however, [they have power because] a new solar energy movement is bringing kilowatts to previously unlit areas of Africa - and changing the lives of hundreds of thousands of people. The idea behind the latest effort isn't to tap the power of the sun to electrify every appliance in a household. Instead, it is to install a small solar panel not much bigger than an iPad to power a few lights, a cellphone charger, and other basic necessities that can still significantly alter people's lives. People use the money they normally would spend on kerosene to finance their solar systems, allowing them to pay in small, affordable installments and not rely on government help. The concept is called pay-as-you-go solar. When [Noah] and her late husband moved into their house in 2004, they paid about a $200 connection fee to TANESCO, the Tanzanian national utility, to extend a power line to their home. After a six-month wait, workers finally erected a utility pole outside their home. But the power never came. I have no idea why it didn't work," Noah says. "All I know is that the lights never came on." They have power now, though, with the help of the sun.