In the developed world, mobile payments can be viewed as largely an extension of services that are already readily available in other forms. In the developing world, the technology can help transform daily life.

Take the case of sub-Saharan Africa, where a number of startup companies are selling pay-as-you-go solar energy kits. According to Scientific American magazine, customers can pay an up-front fee of about $10 for a solar charger kit that includes a two- to five-watt solar panel and a control unit that powers LED lights and charges devices such as mobile phones. They then pay for energy when they need it, and are typically able to pay off the kits in about a year-and-a-half, after which electricity is free.

How do they pay?

Customers of Azuri, one of several start-ups selling solar energy to off-grid customers in installments, can buy scratch-off cards with a code that they send to the company via an SMS message, the magazine said. Customers then receive an unlock code that they enter into their solar kit. Angaza Design of San Francisco has integrated an analog modem into its solar charger that "talks" with the customer's mobile phone to authenticate a transaction. And M-KOPA, a spinoff of the popular M-PESA mobile payment network, accepts payments through its mobile network.

The PAYG program seems to be catching on; Azuri reports 21,000 customers, M-KOPA has 30,000 customers and Angaza is on track to reach 10,000 customers over the next nine to 12 months.

Bryan Silverthorn, that firm's chief technology officer, tells the magazine that feedback has been "aspirational" and that solar kits are giving off-grid Africans the power to dramatically improve their quality of life.

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