[Note: This is the first in an occasional series on gleaner technology.]

In the Philippines, the cost of electricity often means poor citizens are left in the dark—even when the sun is shining.

Social entrepreneur Illac Diaz has come up with an indigenous and ingenious solution for lighting problems in the country’s low-income areas: He use plastic bottles, water, and chlorine to lighten up the dark homes of poor. The solution provides both a cheap source of lighting and environmentally friendly jobs for hard-working entrepreneurs.