How They Are Made
Solar bottle bulbs are simple to construct. A 2-L bottle is filled with water and roughly two capfuls of bleach. A hole is cut in a square piece of corrugated metal and is placed around the bottle to prevent leakage through the roof and to help secure the bottle in place. A hole the same diameter as the bottle is then cut in the roof of the structure, and the bottle is inserted into the hole. The bottle cap is either covered in a protective substance or a plastic covering to protect it from sun damage.
How They Work
The lights work by refracting sunlight in a 360-degree arc around the room, which provides superior light to a window or skylight, only allowing light into a room in a direct beam. The bleach keeps the water clean and clear by preventing algae growth. The bottle lights should last around five years if left undisturbed.
Brazil
In 2002, Alfredo Moser, an engineer in Brazil, got the idea to use solar bottle bulbs in his workshop so that he could continue to work during the energy shortage. His neighbors, intrigued by the idea, soon started following suit, adding the bulbs to their homes in kitchens, bathrooms and living areas where electric light was prohibitively expensive and inefficient.
A Liter of Light
The MyShelter Foundation runs a program in the Philippines called Isang Litrong Liwanag: a Liter of Light. Based on a project developed by students at MIT under the Appropriate Technologies discipline, the project aims to bring sustainable, affordable lighting to the
underprivileged rural communities in the country.