"Very different disciplines have to be perfectly combined"

Exploring the science behind LED light technology

There are many aspects to take into consideration when it comes to growing medicinal-grade cannabis. The medical cannabis industry is a very high-tech sector of agriculture. One of the main reasons is the influence of the pharmaceutical over this: growers are not only growing a plant, but they are crafting medicines. Therefore, medical cannabis producers need to strive for perfection, which, of course, always comes at a cost. This is why it is extremely important to be efficient, and ensure that cannabis plants grow as healthy as possible. One way to be efficient is to opt for a lighting system that can maximize the plants’ genetic potential, while at the same time keeping the operational costs low. “LED technology is able to achieve all of that,” says David Schmidmayr, co-founder of SANlight and CEO of SANlight Solution and SANlight Research GmbH. “However, the low operational cost is only one of the aspects that makes this tech better than any other. Thing is, LED has always been superior to, traditional assimilation lights. But the problem is the complexity of the new technology. In horticulture lighting very different disciplines (botany, photonics, semiconductor physics etc.) have to be perfectly combined in order to fully benefit. This combination on a high knowledge level is quite rare on the market.”

David Schmidmayr 

“SANlight Solution GmbH combines experts of all relevant disciplines – from botany to physics and photonics – in order to make our customers experience the full potential of LED technology. We not only provide state of the art LED illumination systems but overall solutions.” SANlight Research GmbH investigates the interaction of plants and light. “We even go a step further by expanding the research context to all plant related growth parameters. SANlight GmbH develops and manufactures high quality LED-luminaires for horticulture applications as well as customized applications for biomass generation.”

The difference between traditional lighting and LED
David further explains the difference between traditional horticulture lamps and LEDs. “Traditional light sources in horticulture or cannabis production are all based on discharging lamps. A plasma is created within the tube through high voltage, which excites the molecules inside the lamps. Once this has happened, these molecules/atoms drop back down into a lower energy level, thus emitting light. Depending on the chemical composition within the tube, it is possible to tune the spectrum a little bit. The problem here is that this generates high temperatures, and luminaries would be affected by high degradation. Plus, the possibility to tune the spectrum would be incredibly limited.” High amounts of radiated heat are also emitted by these light sources and cause losses.

A complex manufacturing process
“LEDs work in a complete different way. The complexity of the manufacturing process of LED chips can be compared to that of computer chips. There are standards to live up to, like the need for clean rooms. LEDs work through electroluminescence. They are made of semi-conductive materials, which are built-in layers, one on top of each other. In order to obtain different colors of LED light, you need to combine different semi-conductive materials. These are crystalline materials, where atoms keep a certain distance between each other (lattice spacing). Each semiconductor material has its own distinctive lattice spacing. Combining different crystalline materials means that there would not be the same distance between each atom for adjacent semiconductor layers. Some of these combinations do not work ideally, as the lattice mismatch might be too large and cause distinct defects. These defects reduce the light output of an LED chip and generate heat instead of photons. Therefore, at the end of the production process, you have to test each chip to see how many errors there are inside the semi-conductive materials. The more errors there are in there, the less efficient the LED would be.”

“The problem here is that you cannot really see these errors with your naked eye, you cannot see if the quality is decreasing, or is just not good. This makes it very difficult for a customer to objectively determine the quality and performance of an LED luminaire or to be able to compare products. And besides the LED chip efficiency there are many other details e.g. the thermal management, light guidance, spectrum etc. which also contribute to overall performance. I have mentioned only a few aspects but one can already get an idea of the complexity of a high-quality lighting solution and what it takes to fully benefit of LED technology. 

Superior to HPS
According to David, many growers initially did not believe LEDs were suitable for cannabis cultivation, because the majority of LED lights around were not of good quality and the lack of plant knowledge – or botany in general - was obvious. “Many of the early LED suppliers came from other sectors not dealing with plants at all, such as general lighting for instance. And therefore, they promised growers that their product would have allowed them to achieve results that were just not possible.”

David believes that LEDs are superior to HPS, though there are some elements to take into consideration. “In my opinion, with a good LED solution, and a good growing system layout – that is, if everything is done right – you can obtain at least the same results as with HPS and additionally benefit from LED technology – power-savings, lifetime, sustainability, etc.,” he explains. “This means that if one does things properly, the output of the growing operation would be better with LEDs than with HPS.”

A more effective lighting
This difference in the quality of the growing is also caused by the different ways in which HPS and LED produce and direct their light. “If you look at HPS lamps, there is a tube where the light is generated, and the light is sent in all directions. This is why these lamps come with reflective panels, in order for the light to be directed in one direction. Needless to say, this is not particularly efficient, as there would be some loss when it comes to light intensity. With LED, this does not occur, because they do not emit light in all directions and furthermore function as point-light sources. Which means that the emitted light can be steered very efficiently and precisely. This way more light is absorbed by the plants – also in the lower parts.”

David further explains that SANlight has developed an LED lighting technology that works as under canopy as well. “When using any kind of lighting system, and especially HPS, the light goes over the plant, mainly on the top. Thus, the rest of the plant would not benefit from all the light that is produced, as the top would overshadow the rest. We have created an LED technology with a lens system that produces a rectangular shaped light beam which allows it to reach every part of the plant, without the need for installing supplemental lighting. This way we can optimize cannabis yield also in the lower plant regions where growers typically have bad or no yield at all.”

Furthermore, these lenses which are manufactured of optical grade PMMA cover the fragile LEDs and provide a very robust protection against environmental influences such as volatile organic compounds. These can cause severe damage to the LEDs as they have the ability to penetrate silicone and cause chemical reactions inside the LED, eventually leading to rapid degradation.

Future looking bright
But good LED solutions also contribute to drug content quality. E.g. the terpene and cannabinoid profile of the cannabis plant would be higher, also because of the lower temperature that LEDs produce. “A lot of terpenes vaporize already at relatively low temperatures, which you easily reach with discharge lamps. That is why with LED, you can have better terpene profiles.”

According to David, the industry is shifting from traditional discharge lamps to LED exactly because of all the aforementioned reasons. “Growers are seeing the advantages that LEDs bring to their growing operations. It is just a matter of time when HPS etc. will not be used anymore.”

For more information:
SANlight GmbH
Klarenbrunnstraße 46
6700 Bludenz, Austria
+435552 930800
David.schmidmayr@sanlight.com  
sanlight.com  


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