He wanted my suggestion on light output, footprint coverage and color. This ended up being a very big light and it required very deep pockets. The unit failed on both performance and cost.
LED Lighting: A Primer to Lighting the Future - AbeBooks - Sal Cangeloso:
The lumen-per-watt was quite low in comparison to today. As with items like computers, calculators and solar panels, prices have dropped incredibly with vastly increased production. This was to discuss the future needs and applications for manufacturers. At the time, there were about 2, LED manufacturers in the city of Shenzhen alone. I brought in several physicists from large multi-national companies to present. The LED is extremely efficient and produces up to 98 per cent useable light. The color and spectrum can be anything you want, but they have to be defined.
LED is a one-sided light source or plane source. This means much more usable light for plants, and if correctly designed, will produce more performance in plant production. Because LED technology has higher efficiency, with heat evenly distributed via the plane source, an LED light can be placed much closer to plants. This lowers the required wattage. Since LED lights can be used closer to plants, the power to run LED lights can be greatly reduced compared to other lighting technologies and their higher wattage systems. Inverse-square law is a physics rule that helps to understand this. It is also affected in some cases, such as fluorescent, by the milliamp output.
In other words, the light drops drastically the further the fixture is placed from the plants. The LED also drastically reduces heat at the plant level because of even distribution. This is where the physicists, electronic engineers and horticultural testers come in—defining, refining and testing. Another key factor in LED development for horticulture is lumens per watt the amount of light output per watt.
The majority of current LED lights operate at lumens per watt, but some manufacturers are producing considerably more lumen per watt. One Korean design is producing lumens per watt. The sodium light also operates at about lumens per watt. The point source must be converted to plane source usable light via geometry and a reflector.
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Plant elevation is set by reflector design, point source and heat output. In other words, the light has to be both expanded from the arc tube and kept far enough to divert heat and get the light spread out enough from the reflector. The light also has to bounce off the reflector and down and out. Usable light drops off per cent.
How do LEDs work?
For wider coverage, it also has to be raised enough over the plants to get even distribution, and this is set by the reflector. Every foot raised in elevation over the plants is a drastic lumen reduction.
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Lumens fall off hard the farther you are from the light source. For example, reducing the distance between light and plant from two feet to one foot means the plant will have four times the light. Much of the heat is also focused to the arc tube rather than evenly distributed on a sodium fixture. The heat can be reduced with fans, but the point source and reflector determine elevation via lumen distribution. HO 54W T5 lights are defined by the type of phosphorous used and the milliamps mA.
They also utilize point source but distribute the heat better and end up with a much larger point source distribution. The lumen output per watt starts at roughly 90 lumens per watt.
Usable light is improved via the reduced elevation over the plants. The T5 point source is distributed over the entire lamp. The light output of a fluorescent lamp is proportioned to the power of the lamp.
When the lamp current is dropped from mA to mA, the lamp power is dropped, too. Therefore, the light output is dropped as well. These LEDs were tested and met some new criteria. Their minimum was lumens per watt. They are 6. They promise a reasonable return on investment within two years and are convertible for existing hydroponic gear because they are similar to and a direct replacement for T5 fixtures.
These new LEDs are actually strip lights, and this is what I tested. All fixtures were 6. The T5 was tested only with Japanese tri-phosphorous lamps because Chinese phosphorous T5 lamps drop off in lumens too quickly.
Some growers have to replace them every three months, whereas tri-phosphorous lamps can go up to18 months. Energy and heat were both reduced by 33 per cent over the T5. The unit cost on the LED was higher than the T5 but also pays for itself within two years through energy savings.
LED Lighting – A Primer to Lighting the Future
LEDs connected in series as part of an array require higher voltage. Thus, a driver is considered the power supply of LEDs. To control LEDs and achieve affects like dimming or color changing, different controllers are used. So what does it stand for, and how do LEDs work? While not an exhaustive investigation, this blog post will give you a primer on LED lighting technology and how LEDs work.
An LED is hooked up to an energy source. During the drop, energy is released in the form of photons, or small packets of light. The light bounces around in the plastic shell of the LED, and then escapes as visible light.