LED vs HID: the Basics
LED Grow Light Technology, is the newest and most efficient way to grow plants indoors! This revolutionary new form of light, is very different from other horticultural lights, such as High Pressure Sodium (HPS) or Metal Halide (MH). LED Grow Lights are comprised of multiple low-watt light sources, working together on a single board, whereas the other two light sources use single, high power bulbs to spread light over a large area. The most common LED's you will find in current LED Grow Lights, are 1W, 3W, and 5W, while the more common HPS and MH bulbs are 400W, 600W, and 1000W. Unlike High Intensity Discharge (HID) lights (such as HPS or MH), higher wattage LED's do not produce higher lumen per watt values, nor do they have more penetrative ability. If you look at a HID Manufacturer's site, you will notice that a 1000W HPS has the highest lumen per watt value of any HPS bulb, however, if you look at a LED Manufacturer's site, you notice the opposite, as a 1W LED has the highest lumen per watt value. According to the Manufacturers, 1W LED's also have the same penetrative ability as 3W and 5W LED's, although most grow light companies are unaware of these facts. If you look at the charts below, you can see for yourself the difference in light output between 1W and 3W LED's:
1 Watt LED's
3 Watt LED's
(charts from http://www.edison-opto.com.tw/)
Using the 620~630nm LED as an example, the 1W emits 45 lumens, while the 3W emits 80. If we use 3 x 1W LED's instead of a single 3W, we would have 135 lumens, which is 41% more light! It is easy to see that using anything other than multiple 1W LED light sources, reduces the overall efficiency of your LED Grow Light. Beware of companies who try and tell you otherwise! Most will lie to you, saying their 3W's produce more light at a higher intensity, but this is false.
One of the other differences when it comes to understanding how LED grow lights are able to work so well in comparison to HID, is spectral output. A HID light emits nearly the entire spectrum of light, most of which is unused by plants for photosynthesis, while LED's can be tailored to emit only the wavelengths of light used most efficiently for photosynthesis. According to SunMaster (a HID bulb Manufacturer), a 400W HID emits anywhere from 120-140W of light in the PAR (Photosynthetically Active) range, meaning at least 65% of your energy is wasted! When using a properly developed LED Grow Light, up to 100% of the light emitted is within the PAR range. This means that watt for watt, LED is much more efficient at growing plants, as it is tailored specifically for the wavelengths of light they use most efficiently.
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LED's: Photosynthesis and Chlorophyll Absorption
Plants convert light energy into plant energy via a process called photosynthesis. There are two primary compounds that drive photosynthesis: Chlorophyll A, and B. These compounds absorb primarily blue and red light, while nearly all other spectra are reflected. The point at which Chlorophyll converts light energy into plant energy most efficiently, is known as an absorption peak. These peaks can be measured in units called nanometers (nm). Peak absorption points for Chlorophyll A occur at 439nm and 667nm, while they occur at 469nm and 642nm for Chlorophyll B.
LED’s are light sources that emit narrow wavelengths of light, and can be tailored to nearly any nm that you desire. By using LED’s at the same nm as each of the absorption points for Chlorophyll, our lights are able to convert light energy into plant energy more efficiently than ever before! Unlike HID lights, which emit the full spectrum of light (most of which is unused by plants), our Penetrator LED Grow Lights emit only the spectra that plants require, resulting in much higher efficiency in terms of growth per watt. By using the proper ratio of LED’s, 85% - 100% of the light our units create is used for photosynthesis. This means your plants need way fewer watts with our LED’s, to produce the same yields you’re accustomed to under HID, or our competitors' LED Grow Lights! Our Penetrator Grow Lights include 440nm, 470nm, 640nm, 660nm, white and infra-red LED’s. We have dialed-in the perfect ratio of each color, to achieve unbelievable growth during all stages of plant development. We solved the penetration issues associated with most other LED lights, by using 60 degree lenses to create much more intense beams of light, that pierce downward through your canopy. Be prepared for higher yields of greater quality, with no heat stress and lower power bills, when using our Penetrator LED Grow Lights!
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PAR: Photosynthetically Available Radiation
PAR is the spectral range of light between 400nm-700nm, that plants are able to use for photosynthesis. This spectrum corresponds closely with the visible range of the human eye, which peaks at 555nm. PAR is usually expressed in units of micromoles, which is a measurement of the photosynthetic photon flux density of light, within a square meter. Of the 3 methods most commonly used to measure light (Lumens, Lux, PAR), PAR is the most scientific way of determining a light source's ability to drive photosynthesis. It is the only measurement of light which corresponds specifically to plants. On a cloudless day during the peak of summer, the maximum amount of photosynthetic sunlight that hits earths surface, measures approximately 2,000 micromoles per square meter. Environmental factors such as the atmosphere, seasons, clouds, and your position on the earth, affect the amount of available sunlight on any given day.
The amount of light a plant receives, has a direct impact on its growth rate. Most plants tend to grow faster when available light increases, however their maximum growth rate is achieved at a substantially lower amount of sunlight than 2,000 micromoles. The point at which a plant receives more light than they can utilize, is known as the Light Saturation Point. For most plants, the optimum level of PAR lighting is approximately 500 micromoles per square meter (~55 micromoles per square foot), and if these plants receive much over that, they can reach the point of light saturation. In some instances, plants have been observed growing slower when exposed to excess amounts of light, vs growing in their optimal range. For this reason, it is not advisable to supply your plants with more micromoles per meter squared, than what is optimal for their species. Below you will find the light saturation point for several common garden plants, compared to the light output from our LED Grow Lights, and the sun. You can use this graph as a reference for how high to use each of our lights above your crops, depending on what type of plant you are growing.
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Coverage Area, Light Intensity, and Penetration:
Light intensity and coverage area are closely connected when considering a LED Grow Light system, as each affects the other. Both of these measurements are decided by the emitting (or viewing) angle, of the individual LED, which is measured in degrees. The viewing angle is controlled via custom lenses, which either spread or focus the light over any given area. The most commonly used lenses in LED Grow Lights, emit light at 120 degrees. This is considered a wide-angle lens, as it disperses the light from each individual LED over a broad area, as shown in the image above on the left. The use of 120 degree lenses by most companies, is the reason they list large (and often exaggerated) coverage areas for their LED Grow Lights, however there is a definite trade-off between coverage area and light intensity.
For a simple understanding of how the size of a light's coverage area can affect light intensity (and vice-versa), picture yourself with a flashlight at night, about 10 feet away from a building or a wall. If your beam is set to the wide angle, you can see a large area, but the light within that area is dim. If your beam is set to the narrow angle, you can see a smaller area, and the light within that area is much brighter. This same concept applies to the intensity of the light in our LED grow lights, and how it relates to the area it covers. This can be seen by comparing the two lights shown in the image above.
The amount of light intensity from each individual LED determines how far that light is able to penetrate the canopy of your plants. During our testing, we found that 120 degree LED's lack sufficient light intensity to carry energy downwards and penetrate your canopy, since they spread the light too thin over too large an area. We also found that these wide-angle LED's send light to areas where there is no vegetation (like walls), causing a fair amount of it to be wasted. It did not take long during our testing to realize that 120 degree lenses were one of the major down falls of our competitors' products, and would not be an efficient "delivery system" for our lights. Our testing with 120 degree LED's gave us poor results, especially during flowering, so we quickly abandoned them and moved onward with development. By decreasing the viewing angle of our LED's to 60 degrees, we created a beam of light that is 4x more intense than their 120 degree LED's, allowing for much better penetration of your canopy.
Penetration is the key to success with any LED Grow Light, as it directly affects the rate of light absorption. For a plant to be able to absorb light properly, light must pass through or "penetrate" the leaf. This is one of the key reasons why our Penetrator series lights are so efficient, and why we have Patents Pending on the use of 60 degree lenses for LED Grow Lights. After all, we were the first company in the world to implement a 60 degree LED into a LED Grow Light. Without penetration, or with reduced levels of it due to insufficient light intensity (120 degree lens), a plant will use only a small portion of the light they are given, as it's not being "delivered" to them, it simply "rests" on their leaves. So even if you have the perfect spectral outputs, if you don't have sufficient light intensity to allow it to pass through the leaves of your plants, the rate of absorption will be dramatically reduced. Because of our 60 degree lens, our lights provide levels of penetration comparable to HID, and are capable of fully flowering a plant up to 42" tall. Experience for yourself what penetration can do for your plants.
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