Spotlighting Fiber Optics
As electricity costs continue to rise, indoor growers are on the hunt for energy-efficient lighting solutions. Eric Hopper examines how growers can go about harnessing the power of the sun for their indoor gardens.
Of all the vital parts that make up a successful indoor garden, the lighting system uses the most electricity—by a long shot.
All plant growth is possible because of solar radiation, and when solar radiation is taken out of the equation, there must be a replacement energy source to the all-mighty sun. That replacement is high-wattage lighting equipment.
Many lighting companies spend a lot of money researching and developing efficient ways to convert electricity into plant-usable energy.
The HID lighting systems most commonly used by indoor gardeners create a large amount of heat as a by-product when converting electricity into usable light.
The heat emitted from the ballast and the bulb are examples of electricity that was not converted into light but instead became excess heat.
Lighting companies have addressed this by producing other technologies, such as LEDs, induction fluorescents and sulfur plasmas.
But what about using natural sunlight? Is it possible to harness the immense power of the sun while maintaining the control and automation of an indoor garden? And how can you get sunlight into a growroom without compromising control?
There are a couple of options that may soon be cropping up in indoor gardens.
Solar tubes, also known as sun tunnels, light tubes or tubular skylights, are tubes that extend from the roof of a building into a room. The interior of the tube is made from a polished reflective material that acts like a continuous mirror.
This helps channel the light along the entire length of the tube. A solar tube essentially captures the light from the roof of the building and delivers it into the interior of the building.
On the roof, the solar tube is capped with a weather-proof plastic globe. At the base of the tube (inside the building) there is usually a light diffuser to help spread the light.
Although solar tubes have been around in residential and commercial buildings for some time, indoor growers have not really jumped on the solar tube bandwagon due to some limitations.
First of all, these tubes cannot capture and harness a large amount of sunlight—they only capture the sunlight that directly reaches the surface area of the globe on the top of the tube.
Only the amount of sunlight that directly reaches the top of the tube will be available to plants, so you would need multiple solar tubes to effectively distribute enough light energy to grow plants indoors. The entire ceiling of the growing space would need to be solar tubes.
Setting up a garden like this would be so expensive that you would probably opt to build a separate greenhouse instead. Another downfall is the light loss from reflection.
As the light travels down the tube, it loses some of its intensity. Therefore, solar tubes may be a good supplement to artificial lighting within an indoor garden, but would not be a great choice as the primary light source.
Fiber Optics for a Garden?
An optical fiber is a thin, flexible fiber made from glass or plastic. These fibers are commonly used for communications because they permit transmission over longer distances and higher bandwidths than wire cables.
For indoor gardening purposes, optical fibers are also used to transmit light from one end of the fiber to the other.
With fiber optics, a grower could potentially channel the power of the sun into a growroom, so if you want to use the sun as the primary light source for an indoor garden, fiber optics technology has the most potential.
There are a few companies currently offering fiber optic lighting systems to consumers, although this technology is still years away from entering the indoor gardening industry.
The ability to harness the sun and redirect it as needed is every indoor grower’s dream. Here’s a breakdown of the three main components of a fiber optic lighting system—the collector, the cables, and the cable terminal—to give you a better understanding of how it works.
What is the Collector of a Fiber Optic Lighting System?
The collector is the part of a fiber optic lighting system that is placed directly in sunlight to collect solar radiation and direct it into the fiber optic cables for transport.
A lens on the collector will concentrate solar radiation into the input of the fiber optic cables. On some models, the highly efficient lens will condense the sunlight up to 10,000 times.
Collectors can be equipped with an internal clock mechanism, a photosensor and a microprocessor, which all work together to calculate the position of the sun and adjust the angle of the collector.
A solar panel can power the motors that move the collector, enabling it to follow the sun. On clear days, the exact location of the sun is determined mainly by the photosensor.
On cloudy days, the collector relies more on the internal clock mechanism to direct the collector to the most intense solar radiation.
Fiber optic systems must maintain consistent light levels, so precise tracking of the sun is important. Just like solar tubes, the surface area of the collector is directly related to the amount of light energy available to the garden.
However, the lens in the collector magnifies the sun’s intensity, maximizing the amount of light energy harnessed.
The Cables of a Fiber Optic System
Fiber optic cables are the pathways by which the light travels into the building. The length of the cable, the wavelength of the light and the quality of the cable itself all play significant roles in light energy loss.
Fiber optic cables are extremely efficient and do not cause a large loss of light energy. However, to minimize light energy loss, the shortest length of the highest-quality fibers should be used.
Cables can be run through interior wall cavities, ceiling plenums or wiring chases. For most fiber optic cables, the bending radius can be as tight as 2 in. The flexibility of fiber optic cables makes it easy to transport sunlight virtually anywhere.
The Cable Terminal of a Fiber Optic System
The cable terminal, or light fitting, is the point where the light from within the fiber optic cable is distributed to the growroom. This can consist of a series of different light diffusers or lenses that can appear similar to conventional lighting fixtures.
For indoor growing purposes, a fitting that most efficiently diffuses the concentrated sunlight is best. Depending on the size of the collector, multiple light fittings can be operated off of a single collector.
The Future of Fiber Optics and Grow Rooms
It would take the average hobby grower years to recoup the cost of a fiber optic lighting system.
However, there is a lot of potential for fiber optic lighting in indoor gardening applications. Since you would have to purchase a collector relative to the size of the intended growing space, the initial cost of a fiber optic lighting system could be astronomical.
However, several companies have demonstrated that plant growth is possible with the exclusive use of a fiber optic natural lighting system.
As fiber optic costs continue to decline and the cost of electricity continues to increase, this technology will almost certainly become a practical solution for growing plants indoors one day.
Written by Eric Hopper | Writer, Consultant, Product Tester
Eric Hopper’s past experiences within the indoor gardening industry include being a hydroponic retail store manager and owner. Currently, he works as a writer, consultant and product tester for various indoor horticulture companies. His inquisitive nature keeps him busy seeking new technologies and methods that could help maximize a garden’s performance.