What is “liter of light”? It’s a clear plastic soda bottle filled with filtered water and bleach and installed in the roof as a skylight. The water refracts the sunlight as it streams through the bottle, dispersing the rays 360 degrees, thereby illuminating the entire room. The recipients of the solar bottle bulbs, who pay about $1 for the bulb installation, save money on electricity and cut back on the use of kerosene, candles, and other fuels that are responsible for indoor air pollution and fire hazards. – Illiac Diaz, activist and Filipino entrepreneur.