Project goal: The "Solartainer" brings clean power to off-grid villages to stimulate economic activity and encourage people to stay in their communities, while ensuring that development has a low climate impact.

Budget: The solar power unit costs about 150,000 euros ($160,000). Consumers pay for the power they use, meaning the initial cost is recouped in around 15 years.

Partner organizations: The International Climate Initiative of the German Environment Ministry financed a prototype of the Africa GreenTec Solartainer in Niger. Since then, Africa GreenTec has worked with private donors to bring the technology to communities in Mali.

It's a big day in Sirakoro as trucks arrive, finally bringing the Malian village its own source of power. Aida and Torsten Schreiber founded Africa GreenTec to bring sustainable economic development to remote communities like Sirakoro. Their Solartainer comprises a photovoltaic unit and rechargeable battery pack, and can supply more than 400 connections. For small businesses in particular, this brings new opportunities to power machinery — or perhaps a fridge — all with renewable energy from the sun.

A film by Jürgen Schneider