Please see http://www.openideo.com/challenge/womens-safety/research/light-up-the-darkness-illuminate-urban-slums-with-low-cost-solar-technology-that-is-marketted-installed-maintained-by-women as well - he has built quite well on the idea
One thing I've noticed in Australia is solar powered real estate sign lighting. (http://www.lightasign.com/). If this could be provided cheaply to the third worls it would go a long way to making areas safer. It would also not rely on existing electrical infrastructure.