Targeted toward people in poor countries, this power supply, sold with a photovoltaic panel, provides electricity only after the user sends a code from a prepaid card over a mobile phone. The code unlocks the system until a set number of kilowatt-hours is consumed. Users buy cards until the cost of the entire system has been paid off, after which it unlocks permanently.
Product: Simpa solar energy system
Cost: Starting at $150
Availability: January 2012
Companies: Simpa Networks