Hybrid Solar Lighting

Sun has always been the main source of lighting however with the advent of electricity areas without direct access to sunlight have become easier to illuminate. However different methods were used for lighting the places like underground vaults, basements, storage chambers and rooms with fewer openings and direct access to sunlight. Most of these methods were based on principles of reflection and refractions, with mirrors and prisms being used to route light. But with the advent of electricity we  started relying on it for light. But given the electricity costs for lighting and heat and with the increase in environment awareness different techniques have come to the fore for reducing the impact on the environment.  One of these techniques which piqued my interest is HYBRID SOLAR LIGHTING {HSL}

Hybrid Solar Lighting (HSL) system uses artificial light in conjunction with sunlight for illumination. Sunlight is channeled into rooms without direct access to sunlight, i.e. underground rooms or rooms without windows or skylights, using Optical Fibers and supplemented by artificial or electrical lights where required, thereby reducing the running costs for lighting areas with electricity alone.

HSL consists of a collection unit, usually placed in an area with direct sunlight such as rooftops, which focuses the sunlight onto Optical Fibers. The flexible optical fibers then convey the lights to hybrid light fixtures, called luminaries, which are built to diffuse the sunlight and provide lighting in all directions. The setup is called hybrid because it also uses artificial light to supplement sunlight where required. The amount of artificial light can be monitored using a photoelectric light sensor.                                                            


An HSL made up of 4ft wide collector and 127 optical fibers can adequately light up an area of around 1000 sq ft.


It is a good way to save energy and cost. The cost is not just saved from the reduced artificial lighting but also from the reduced cooling requirement in hot climate because Infra-red and ultraviolet part of sunlight is not transmitted to the interior. Moreover it also means reduced Carbon dioxide emissions. The light that penetrates and comes from the optical fiber is full spectrum unlike most bulbs which only provide narrow band of light. Unlike solar panels , HSL systems have high efficiency because most of the light energy is transmitted through the fiber optics unlike solar panels where a lot of energy is lost .


One of the setback of this technology is the initial cost. It almost costs $40, 000 to light up to 10,000 sq ft. But I believe with the advancement of technology it will come down. In 2012 students of university of Maryland used this technology and figured out the payback time is almost three years if they light up a hall.

So we can think of it as a step towards lighting buildings while being environment conscious.

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