Light is one of the most essential human needs. When it comes to illumination, people logically demand light for the night time. Day time lighting is usually covered sufficiently by the sun light but in the slums the situation is different.
In densely populated areas like slums and even some rural areas, household often lack windows or light passages. As a result, these households remain dark or very poorly lit even during sunny days, resulting in an unnecessary energy demand. This demand can be efficiently met by the solar PV system- plastic bottles or solar bottle light which is way cheaper and simpler.