Looking for the best LED Grow Lights? Be sure to also check out our list of top rated LED grow lights for 2015-2016.
As the name suggests, grow lights are electrical lighting sources which help in growth of plants by aiding the process of photosynthesis. In nature, the lighting source is the sun, which transmits the whole spectrum of visible light onto the earth’s surface. This full spectrum or white light, as it is normally called, is absorbed by the plants and used as a source of energy for various biological processes in the plant’s body. However, as we shall see below, it is not always possible for plants to obtain the amount of natural light they require. In nature, this may occur due to the presence of winter (when the weakness of the light reaching the troposphere is sometimes too weak for plant sustenance, especially in the temperate and polar zones), or presence of canopy due to the existence of larger trees (eg. In tropical forests). Plants have a variety of mechanisms for adapting to such exigencies, but adaptation is limited and the more the plant has to expend its energy to adapt, the less efficient its flowering/fruiting processes. In fact, horticulturists and botanists argue that each plant has a specific optimal height and foliage range, within which it produces maximum yield. If the plant becomes too stunted or too tall, yield suffers drastically. While in nature this translates into the rise and fall of various plant species, in commercial cultivation of plants such exigencies occur due to different reasons, and can have serious commercial implications. The reasons for plants not receiving sufficient light are –
- Poor location (inside houses, under stairs, etc)
- Nightfall (which can be especially damaging in the polar regions, where nights and days are typically longer and the plants being grown belong to another climate)
- Extensive rainfall (a risk in tropical and monsoon regions, since overcast skies allow for less light penetration to the ground level)
One of the topical solutions for overcoming such lighting constraints is to cultivate plants – usually for horticulture or medicinal purposes – inside the house. Within the house (or on a covered terrace), the plants can be kept protected from excess heat or frost (both of which are very harmful), and if calibrated with a proper light source, can be induced to produce the exact level of fruits/flowers expected of them. Now while it is not impossible to raise plants using natural light while keeping them inside the house, this solution exposes the plants to all the lighting problems given above. The solution is therefore, artificial light that can mimic the natural light and allow plants to photosynthesize without being exposed to the vagaries of nature. When working around such lights, don’t forget about wearing safety grow room glasses.
Such lights are called grow lights, and they can be made from any type of light bulb, provided it is able to provide the specific bands of the light spectrum that plants need to photosynthesize (see below). Of course, each light bulb type has its own advantages and disadvantages, and as growers and horticulturists become more conscious of the vitality of the light source in the proper growth of their plants, the industry for grow lights has become more and more specialized. One of the most recent innovations in this field is the introduction of LED technology. LED grow lights, like older types, provide the necessary spectrum to plants, but do so through a method which is far more energy conserving than any previously known. This, along with a number of benefits which are limited to LED technology alone and the steady reduction of the cost, has made LED lights one of the most preferred types of grow lights in the world today. Indeed, according to the WinterGreen Research LED Grow Light Market Shares, Strategies, and Forecasts, Worldwide, 2014-2020, the market for LED grow lights is set to grow rapidly in the next six years, moving from $395 million in 2013 to about $3.6 billion in 2020. Indeed, the major part of this growth will be driven by increased demand from restaurant and home owners who are becoming increasingly conscious of the deleterious effects of fast foods, etc. ,and wish to replace eating out habits with home-grown foods using efficient lighting technology and advanced automated indoor farming processes. Before we look into the benefits driving this growth, however, we need to know a little more about the different types of lights and the grow light technologies available in the market today.
Types of Lights For Plant Growth
We mentioned that plants use the natural light of the sun, which is full spectrum light containing all the color bands in visible light. However, this does not mean that plants utilize all parts of the visible spectrum. Indeed, their requirements are limited to certain small bands in the spectrum, the rest of the light incident on them being simply rejected. This implies that sunlight is rather inefficient as a source of plant light energy, but due to its abundance, such wastage is rarely noticed. In the house, however, you have to provide the lighting, and wasteful lighting can be harmful to both your plants and your pocket. Therefore, it is important to see the ideal spectra for indoor grow lights. # Red Light Band: Red lighting is required by plants for achieving hormone activation, which is vital to the flowering and fruiting processes. In general, red lights are ideal for producing blooms. # Blue Light Band:Blue lighting encourages the growth of vegetative processes, which help in the plant acquiring a compact bushy appearance. Hence, horticulturists suggest the changing of lighting from one growth stage to the other, so that the exact spectrum necessary for the plant is achieved. Now let us see how the different lighting technologies available in the market today conform to the above spectral requirements, and whether they have any positive or negative points vis-à-vis other forms of lighting.
1. Incandescent Lighting
Perhaps the oldest and cheapest form of lighting, incandescent lights typically produce full spectrum white light, though color correction is possible to some extent to achieve a more suitable spectral allocation. Further, they are the cheapest, being priced at a mere $30 a piece. As you’d expect, incandescent lights are also the most inefficient, since they produce only a small part of the red and/or blue light required by the plants. Further, they tend to heat easily, and it is therefore necessary to place them at least 24 cm away from the plant or soil surface. If this precaution is not applied, the heat from the incandescent light will suck moisture away from the plant and the soil, thus retarding food production processes. Lastly, they come with a poor 1,000 hour lifecycle that requires frequent alteration.
2. Halogen Lighting
A type of incandescent lighting, halogen lights typically light a narrow region intensely, and produce a great amount of heat in the process. Though their spectral region is conducive to plants requiring red light, they typically suffer from all the problems of incandescent lighting, along with the specific issues of narrow region of illumination and excess heat production (which is harmful for plants and reduces efficiency). Halogens are rarely used as grow lights nowadays.
3. Fluorescent lights
Priced slightly higher than incandescent lights, fluorescent lights can provide up to 20,000 hours lifecycle, which makes them ideal candidates for home growers. Further, they produce little or no heat, thereby allowing the grower to place them in close proximity to the plants, thereby saving space. One feature, which can be a shortcoming or a benefit (depending on the type of plant and its growth stage) is that such lights typically tend towards the blue end of the spectrum, thereby encouraging bushy growth. While this may prove to be a boon for some, it may not be ideal for plants entering their flowering stages.
4. Full spectrum fluorescent lights
As technology has progressed, fluorescent lights have been modified to provide the red area of the light spectrum as well. Combining the two, the complete light spectrum can be achieved in a panel. Of late, further improvement has allowed for the introduction of T5 panel lights, which offer 3 times as much output at the same wattage as compared to an ordinary fluorescent light. The shortcoming of this type of lighting is the high upfront cost, since ordinary fluorescent fixtures cannot handle these efficient lights, and new fixtures designed specifically for such lights have to be installed.
5. High Intensity Discharge lights (HIDs)
Among the more popular options, HIDs have been used since the 1960s to provide powerful light output with comparatively small bulb sizes. Two of the major benefits of HIDs is that they are cheaper than the other lighting options mentioned above, and offer the full spectrum of lighting if two types of lights are used (mentioned below). Though commercial household lighting varies from as low as 200W to higher than 1000W, growers generally prefer lights in the 400W to 1000W range. HIDs are of two types – # High Pressure Sodium
High Pressure Sodium or HPS is useful for achieving light in the orange and red area of the spectrum, which makes it ideal for use during the flowering period. Though the lights can be used for the whole growing period, doing so would result in tall and spindly plants that are unable to make full use of the red spectrum when they reach flowering stages. # Metal Halide Metal halide bulbs take care of the blue region of the light spectrum, and are therefore ideal for the early vegetative period of plant growth. They too can be used for the entire period of plant development, but generally if your budget allows you only one HID light, HPS is a considerably better option.
6. LED grow lights
As noted above, these lights are witnessing a phenomenal growth in the indoor growing industry. LED lights use diodes to produce the necessary light, which allows engineers to control the light spectrum in much greater detail than is possible for other types of bulbs. They typically come in arrays of small LEDs, which can be fixed over plant grids as per convenience. This implies that while you can purchase readymade arrays to fix quickly, you can also order individual LEDs to arrange according to the grids you are creating in your indoor garden. Furthermore, since they produce little heat as compared to light, they can be placed quite close to the plants without risk of the latter drying up. Despite these advantages (which will be explored in greater detail below), the price of LEDs proved to be prohibitive for growers for a long time. Only recently has this changed, and though they may still be costlier than incandescents, they are now well within the budget of the ordinary grower, which goes a long way in explaining the trends forecasted by the WinterGreen Research LED Grow Light Market Shares, Strategies, and Forecasts, Worldwide, 2014-2020.
Grow Light Comparison Chart
|Type of Light||Price||Efficiency||Color Spectrum||Dimming Potential||Usual Lifespan||Heat Production/Distance From Plant Surface||Other Points|
|Incandescent||Very low ($30 apiece)||Poor||White Light Only, special filters needed for colored light||Poor||Poor (1,000 hours)||High heat production / 24cm||Not suitable for arrays|
|Fluorescent/ Compact Fluorescent (CFL lights)||Slightly Higher than incandescent ($50-80)||Average||Blue Light only||Poor||Average (20,000 hours)||Low heat production / close proximity|
|Full Spectrum CFL||High, especially with special fixtures||Good (3 times that of ordinary CFL)||Entire spectrum of visible light||Poor||Average||Low heat production / close proximity||Require special arrays for T5 lights|
|Halogen High Intensity Discharge (MH/HPS)||Low (lower than Full spectrum CFL)||Good||MH – Blue Spectrum HPS – Red Spectrum||Decent with special ballast||Good||High heat production /1m distance from plant surface|
|LED||Low||Excellent||Targeted Spectrum lighting possible||High dimming ability||50,000 – 100,000 hours||Negligible heat/ Very close to plant or soil surface||Highly flexible designs for easy modification|
HID vs. LED Grow Light
Why LED Grow Light Is The Best Choice?
Now that we know of the various types of lighting solutions available today, we can analyze the characteristic benefits of LED lights in greater detail. # Specific wavelengths can be targeted As we noted above, the use of LED technology allows for creation of lights which target certain specific wavelengths rather than provide a broad and often inefficient distribution of light over a large spectrum. Though full spectrum LEDs do exist (and indeed are the most common), wisdom lies in using LEDs which provide the maximum light in the 400 to 500nm (nanometer) and 600 to 700nm regions, which are most preferred by plants for photosynthesis. Such grow lights will allow the plants to absorb the right amount of light energy at the right time, provided the right LEDs are used during the corresponding part of the growth process. This, apart from benefitting the plants, ensures that there is little wastage of electricity in producing lights which the plants have no use of. # Excellent lifetime
LED lights produce very little heat and this, coupled with their internal dynamics, ensures a long lifetime of between 50,000 to 100, 000 hours. What this means is that these lights can be used for up to 11 hours continuously, and more practically, for 22 years at half time. Not only is this time frame enough to recover the initial input costs many times over, it also ensures that frequent maintenance (due to dead bulbs or other problems) is not an issue. Given that plants need continuous lighting for long periods of time, frequent maintenance disruptions can have an adverse effect on the overall growth cycle, and this can impact the quality of the output regardless of the availability of other factors. # Gradual dimming LED grow lights gradually fade out, losing luminosity as they near the end of their long lifespan. Of course such fading out reduces the overall efficacy of the light produced, but this also gives the user a forewarning of the approaching demise of the LED bulb. A panel with a number of such gradually dimming bulbs can be replaced ahead of its actual expiry, so as to ensure that the plants don’t have to suffer from “dark days”. This is in marked contrast to the incandescent and HID bulbs, which tend to die out quickly when they reach the end of their lifespan, thus giving the user no time to stock a spare bulb or panel in advance. # Flexibility of Design Unlike the other types of grow lights, which are bulky and hence can be arranged in a finite number of arrangements, LED grow lights can be arranged in a wide range of arrays depending on the growing needs of the horticulturist. Indeed, LED strips and even individual LEDs can be taken and combined into structures capable of working together to illuminate unconventional plant grids. Indeed, some of the most efficient new-age arrangements such as inter-lighting designs between plants and multilayer vertical systems can only be achieved using LED lights. # Greater energy conversion efficiency One of the primary concerns of growers regarding HIDs or incandescents is the high amount of heat produced. Heat, as we noted above, can prove detrimental to the lifespan of the plant, and even kill it off. The traditional solution to this has been to keep the lights at a great distance from the plants, but this proves to be a problem due to the operation of the inverse square law (explained below). LED lights, however, produce little to no heat (less than 10% of the heat produced by HPS bulbs of similar wattage) as they convert a large portion of their electricity supply to light energy. This means that the LED lights can be placed in close proximity to the plants, thereby ensuring optimal absorption of light. Coupled with the flexibility of design mentioned above, this proximity has made possible close multi-layered arrays which would have earlier been unthinkable.
# Huge Energy Savings Energy efficiency converts directly into reduction of electricity costs, and through it, to the lessening of the overhead cost involved in growing plants indoors. Studies have shown that the higher efficiency of the LED lights translates directly into 40% lower electricity costs as compared to HIDs of similar power in a general setting. A more specific study using tomato plants showed a much higher – 75% – saving of electricity as compared to a similar setup using HPS bulbs. As these indicate quite clearly, LED lights are the more pocket friendly solution for small home growers (who do not have economies of scale on their side to cover the huge overhead costs), while offering a more economical option for commercial growers. Last but not least, such energy efficiency reduces the burden on our limited conventional sources of energy and through it, gives impetus to the vision of a sustainable future for human energy needs. # Now Available In Required Wattage The earliest iterations of LED grow lights were weak products of just 10 to 20W. However, these days products of 100W or more have appeared, which can successfully challenge the efficacy of older incandescent and HID lights of much higher wattage in terms of luminosity, while saving the user valuable money. This means that grow lights of the LED variety are now applicable in a wide range of indoor horticultural setups, instead of being limited to just the smaller ones. Furthermore, though LEDs with higher wattage produce more heat, the rise is insignificant compared to the rise in heat output noted in case of HIDs.
The “How” and “What” of LED Grow Lights
We mentioned earlier that the LED grow lights are a recent innovation, with the fall in prices of these lights being an even more recent development. Such statements raise the question – “How did these lights emerge?”. Before we can answer this question, we need to see the history of LEDs briefly, and figure out just how they work.
How do LEDs work ?
In order to understand LED, or to call them by their proper name, Light Emitting Diodes, we need to understand semiconductors and electroluminescence. Semiconductors are elements (or compounds) which have conductivity between that of conductors (like metals) and insulators (like glass). A process called doping is used to add impurities to the semiconductor so as to create two different types of semiconductor layers in the same chip. This happens because the impurity modifies the electron configuration of some of the atoms of the material, thereby rendering some atoms electron deficient (possessing “electron holes”) and some electron surplus. One layer becomes electron deficient, while the other becomes electron surplus. The junction of these two layers is called a p-n junction, and this p-n junction forms the foundation of all LEDs.
Electricity being essentially the movement of electrons through the element, it can only flow from the negatively charged electron-excess region to the positively charged electron-deficit region, or in other words, electricity can flow only in one direction across the p-n junction. Now electrons move from the negatively charged atoms to positively charged atoms, they fill the deficit areas (called “electron holes”) in the positively charged atoms. While filling them, they emit photons by the process of electroluminescence. These photons are “particles” of light, and when they are emitted in sufficient quantity, we can say that the p-n junction is emitting light. The process by which this is turned into a fully functional LED is too complex to cover here, though if you want a more in-depth analysis, you can refer to this paper.
Brief background of the evolution of LEDs
Now though the concepts of semiconductors and electroluminescence were known in the early 20th Century, research into semiconductors proper began only during the World War II. By the early 1960s, the technology had advanced sufficiently for a number of American and Japanese companies to be in the race to produce commercially viable semiconductor solutions using gallium arsenide, germanium and later silicon. The major breakthrough was achieved in 1961 when the team of Bob Biard and Gary Pittman succeeded in discovering the infrared LED while trying to produce a semiconductor laser. A year later, Nick Holonyack Jr. came up with the first LED in the visible part of the light spectrum – the light LED. A decade later, the yellow and violet LEDs appeared, while in 1979, Shuji Nakamura produced the first blue LED.
Commercial marketing of LEDs had begun much before of course, with Texas Instruments getting the first patent for the commercial LED in 1962. The product them came up with, however, cost $130 apiece, which made it extremely costly for the time. Over the years, however, prices of LEDs have dropped, and today we have LEDs being used in the great majority of electrical implements.
History of LED grow lights
Such diversification of LED applications influenced the grow lights industry rather late. It was only in the early 21st Century that attempts were made to create arrays of 120 5mm diodes to produce commercial grow lights. Such arrays made use of up to 5 different types of LEDs, two in the red light region, one in the orange/yellow region and two in the blue region. Such an arrangement attempted to create the natural absorption spectrum of chlorophyll and carotenoids, which are the primary energy conversion materials in the plant leaves. The original attempt offered very poor wattage, leading to less than promising results when applied in indoor gardening. Coupled with the fact that one array cost about $100, this method offered too low a rate of returns on investment to be sustainable in the long run. Another attempt made by GES Electric in 2003 used only one type of red LED and one type of blue LED, assuming that by targeting the exact peak absorption wavelengths, the ideal grow light could be created. Rather ironically, it was found that this ultra-specific approach did not yield the correct dividends. Instead, lights which tended towards the middle of the photosynthentically active region could achieve four times the growth as compared to the former array. Initially, the costs of this product were quite high, and the average grower required about 3.5 years to recoup the initial price difference (between LED lights and HID lights) in terms of power savings. Further, the benefits of low heat production and presence of UV rays could only be used by violet and orchid growers. Constant fine tuning over the past decade, however, has allowed prices to fall significantly, even as technology has improved. Today LED grow lights offer a wide range of spectrums and users can choose to buy light arrays catering to various “bands” of spectrum depending on what the needs of their plants are (see “Types of LED lights”). More importantly, the prices offered today allow the average grower to recoup the price difference in just 18 months (assuming the replacement of 1000W of HID lighting with 350W LED lighting, which provide the same light output due to greater efficacy of the latter). Indeed, the time period is even lower in cases of large commercial entities. It is not surprising, therefore, that LED lights are rapidly displacing MH and HPS grow lights as the favorite type of lighting for indoor horticultural practices.
Uses of LED Grow Lights Today
Given the benefits and growing affordability of LED grow lights, it should perhaps not surprise us to know that their applications are growing by the day. Indeed, even NASA is planning on using them to grow food in space! Before we come to NASA, however, let us see the more mundane applications of LED grow lights in the world today.
In commercial horticulture and orchards
Remember our reference at the beginning of our essay to the possible reasons why commercial growers may be faced with the issue of insufficient natural lighting, and how grow lights were the only possible solution to the problem? As the above sections would have made clear to you, LED grow lights are the best type of grow lights available today, so it is perhaps not surprising that with the rapid reduction of upfront costs of installing LED lights, their usage has risen dramatically. Interestingly, the early adoption of LED grow lights was not due to the one factor vital to commercial farming – returns on investment. As we noted, the earliest lights were many times costlier compared to HID grow lights, and were rather inefficient as well. However, they offered a number of unique advantages, such as the absence of heating. Given the closed indoor greenhouse complexes and the thousands of lights being used, heating can prove to be a major danger for the commercial concern. Matters are made worse by the fact that commercial lights have to stay on for 14-16 hours at a stretch in order to emulate the natural daylight. With LEDs however, the amount of heat produced over time is negligible enough for them to be touched by hand. This does not mean that LEDs do not produce heat at all, but rather that the heat does not escape in all directions. Instead, special cooling mechanisms are used to funnel out the heat without affecting the plants. This lack of heating, coupled with other benefits like possible emission of UV rays (if needed), dimming capabilities and later, cost reductions, is triggering a massive shift away from HIDs to LEDs among commercial growers.
Medical and Recreational Marijuana
Even as debate rages on about the desirability of allowing ordinary citizens to grow marijuana, a number of states in the US has legalized the production of marijuana for medical purposes (and a handful, for recreational purposes as well). However, society is yet to accept the growing, sale and consumption of the herb, and therefore, growing the leafy plant outdoors is often considered something borderline illegal. Furthermore, marijuana is not a native plant of the colder regions, and especially in areas witness to snow and sleet, outdoor cultivation is simply unfeasible. The solution is to grow marijuana – medical or recreational – indoors, in specially designed rooms. Rather fortuitously the fall in pricing of LED grow lights has coincided with the gradual relaxation of marijuana growing norms in a number of US states. This implies that unlike traditional horticultural industries, marijuana growers have no legacy of using HIDs, and this has helped them take up LEDs directly. Luck apart, LEDs have proved themselves to be superior to other lighting options. Part of the reason lies in their cost effectiveness, since many of the growers of recreational marijuana do not wish to expend huge sums at the start. Part of the reason also lies in the fact that marijuana is best grown using specialized techniques such as Sea of Green (SoG) and Screen of Green (SCroG). Finally, the success of LEDs is due to the fact that they can be purchased in customized arrays and fitted according to need, since informal indoor growing is often a space-constrained exercise involving attics and basements.
Barely half as important as commercial horticulture, aquarium lighting is nevertheless a growing industry which is benefitting from the introduction of LED lights. Like terrestrial plants, marine and freshwater plants also use chlorophyll for photosynthesis (though the type of chlorophyll may vary). Hence, LED grow lights serve pretty much the same purpose in aquariums as in the indoor garden. The difference, of course, is that huge arrays of high power lighting are not possible for two reasons. Firstly, aquariums tend to be small in general, and even within them, lighting has to be limited to certain corners, lest the fauna be disturbed. Secondly, it is crucial that the light used not produce huge amounts of heat, for water absorbs heat quickly and the resultant rise in temperature can reduce the longevity of the fishes. LED lights, by offering low heat high luminosity configurations, ensure that the plants in the aquarium receive sufficient light but the fauna is not disturbed due to excess heat. Further, they generally tend to be smaller than HIDs, and this allows them to be placed strategically, so that they neither hurt the plants or fishes, nor become an eyesore for the viewers. Due to these reasons, LED grow lights have been gaining popularity in the aquarium industry, and many sellers and fish breeders promote the use of LED lights for aquariums. Indeed, companies selling aquariums have even begun stocking LED lights or even better, producing them for customers. As the variety of designs and power ratings of the aquarium LED lights steadily increase, it is expected that they will easily surpass the existing aquarium lighting solutions.
And finally, NASA!
While farms in space may yet be the stuff of science fiction novels, it is a fact that astronauts need fresh foods to survive for long periods in space. NASA, therefore, has been running tests using artificial growth chambers to see which plants can grow well under which lights. Interestingly, red LEDs were the original choice of the NASA scientists, long before they had been popularized in everyday electronic gadgets. The reason, as Gioaia Massa, a postdoctoral fellow at NASA explains, is that “LED lights are efficient and versatile. Because of their durability and long life, they are ideal for space missions where resupply of things from Earth is limited.” Unfortunately, the red LEDs did not produce encouraging results, and blue CFL lights had to be used instead. However, when blue LEDs became cheaper in the 1990s, CFLs were replaced by these LED lights, resulting in significant improvement. In recent years, NASA has shifted focus to the growth of certain antioxidants which fortify the body against cosmic radiation. A recent experiment conducted using red lettuce and radishes sought to measure the production of antioxidants under red and blue LEDs and also under broad spectrum fluorescent lamps that had green light as part of their spectrum. According to Dr. Matthew Mickens, one of the researchers who worked on the project, the plants grown under LEDs evinced a deeper red colour, which indicated better presence of anthocyanin, one of the most important antioxidants used by the body against radiation. Currently, replication tests are being run, and it is anticipated that other sources of anthocyanin, such as tomatoes, would be tested with these LED grow lights soon. Don’t believe us? Then check out this link.
Choosing the Best LED grow light
Having read of all the good features that LED grow lights offer, it is now time to see how to actually go about the business of setting up your own indoor garden using LED lights. To be fair, you may already have a garden, and if so, can skip some of the steps that you may already have completed. Irrespective of whether you are a gardening pro (with other types of grow lights), or a beginner, you must first the features that make a good LED grow light. Otherwise, you may end up suffering losses of time, money, enthusiasm and of course, precious seed/plants. # Light Intensity, Wattage and Lamp Size From the above discussion, it is clear that LEDs consume much lower power than other bulbs. This means that LEDs should ideally have a much lower wattage than conventional HIDs (as indicated in a table below. However, it is equally true that the minimum wattage of the individual LED should not be less than 1W if it is to have sufficient penetrative power. Mind you, by individual LED we mean each LED lamp and not the whole array. Hence, an effective LED array of 300 lamps will not be lower than 300W, even when LED lights used for purposes other than growing prove useful at lower power ratings. More troublesome can be the lamp size. Experts believe that lamps smaller than 10mm are not capable of producing sufficient luminosity. In other words, all lamps of the array need to be of this size irrespective of the light color they are producing. The sad part is that it is extremely difficult to measure this out without precision apparatus, so if you’ve purchased a LED grow light array and there is no mention of the individual lamp size, there is not much that can be done about it. To be safe than sorry, it is better to inquire with store owners and experienced growers regarding the companies which do adhere to this rule, and the ones which share this information on the package. Conversely, if you find this information on the package and see that the details are verified by a reliable authority (see below), you can consider the manufacturer to be truthful and dependable. # A Spectrum That Can Be Adjusted As Per Need While analyzing the benefits of LED lights, we mentioned that LED lights can be tailored to meet the exact spectrum needs of the plants. This holds true for the same plant during the different phases of its growth as well. However, adjustment of the spectrum to suit the plant’s growth needs is not as simple as switching off one type of light (say blue during the flowering period), because the change must be gradual, like the seasons themselves.
The solution is to dim out one color of LED lights gradually even as the other is gradually strengthened. For instance, if a plant goes through the vegetative phase in summer and the flowering phase in autumn, it is imperative that the blue lights be dimmed gradually and the red light be increased in step with the changes occurring in the plant’s physiology. As may be obvious, this means that the LED light in question must have independent dimmers for each of the different colors of LED lights, such that the simultaneous increase or decrease in intensity can mimic a growth cycle of many months’ duration. While this is important for both home growers and commercial growers, it is more vital for the latter because their viability often depends on their ability to provide the plants which are naturally not available during that particular season. Furthermore, they are often called upon to grow plants at short durations, thereby eliminating any possibility of seeking the sun’s help. In such cases, if the dimming is not one correctly, the plant hormones will not activate at the right time, leading to wastage and monetary losses. # Component Nomenclature Top manufacturers spend fortunes sourcing quality parts from dependable providers, and are justly proud of their focus on quality. Hence, in a large number of cases, the individual components’ manufacturers will be listed in the specifications, and while not all of them may be familiar to you (even Google doesn’t help sometimes), most should have at least some presence on the internet. Searching out the individual parts developers’ names can be a time-taking and tiring job, but if done thoroughly once, can save you a good amount of money in the long run. Conversely, fly by night manufacturers typically don’t mention the parts’ manufacturers, possibly because they’ve been sourced from used units or made by equally suspicious companies. # The brightness fallacy Our eyes are attuned to perceive light around the 550nm mark as optimal, and so we regard any light that is higher or lower in intensity as poor and lacking “brightness”. However, plants have a different spectrum necessity and it is not surprising therefore that the high quality red and green lights that are sold in the market appear dim to us. Such lights, as have been shown in numerous cases, are indeed more optimal for plants than the “bright” HIDs, which appear brighter to us because they produce light in the yellow/green area of the spectrum as well. What such HIDs are actually doing, however, is wasting the electricity to impress our eyes. Unfortunately, many growers are confused by this and continue to argue that even best quality LEDs are not good enough. No matter how good the grower may be at using HIDs, if he doesn’t have experience with LED grow lights, it is better to believe the product reviews regarding the LED light’s capabilities rather than believe such misguided growers. # Constant Current vs Constant Voltage driver circuits Though the physics of voltage-current relationship can be rather confusing, it is important to know that the LEDs are fed by driver circuits that convert fluctuating AC current into the DC current needed by the LEDs. This DC current is independent of the AC current, but may or may not be constant. If the driver circuit is “constant voltage”, it will supply current in accordance with the voltage. According to the rules of physics, passing of electricity through anybody leads to a certain part being converted into heat, and LEDs are no exception to this rule. As they gradually heat up the voltage begins to fall. The fall in voltage causes the current to rise, thereby causing even faster heating and further fall of voltage. The feedback loop thus created continues till the amount of heat produced is too much for the internal circuits of the LED to bear, and the lighting system fries out.
Since it is assumed by default that indoor gardening will require lighting of LED lights for long periods at a stretch, this threat is a real one that can even cause a fire. The solution is to use a “constant current” driver circuit that maintains the same level of DC current to the LED light regardless of the level of voltage. This ensures that the current does not rise with temperature, and the device can continue working flawlessly for long periods of time. # MCPCB Based Cooling System LED lights are famous for not emitting heat, but they do become hot inside. The need therefore is to draw out the heat in an efficient manner. This is usually done by means of a metal slug, circuit board and a heat sink. As the heat moves from the metal slug to the circuit board, the circuit board has to bear the entire brunt of the heating. Ordinary fiberglass circuit boards are not designed to handle such heat, and therefore, chances are that they may fry, leading to heat accumulation in the LED die and eventual collapse of the entire system with possibility of a fire breaking out.
LED grow lights, therefore, have to be cooled using Metal Core PCBs (MCPCB), which are space grade technology and can handle huge amounts of heat. Further, once the heat is passed by the MCPCB into the heat sink, the latter should be able to handle it without problems. Generally, it has been found that the heat sinks with greater number of fins handle higher amounts of heat better. Finally, there should be multiple fans in the heat sink, so that even if one or two collapse, the others can continue working. In general, features such as the type of driver circuit used, the nature of PCB and other specifications are given on the packaging and are available in the company’s website. However, there are chances that small companies may not state actual facts. This necessitates verification by experts – Unfortunately, apart from government regulators, there are not many bodies which are universally recognized as impartial and rigorous testers. Usually then, companies go to universities and request their faculty to test the lights using their resources. Results of such tests, if genuine, should be available on the website of the university or of the company, and can be cross checked. Small private universities which partner with upstart companies should not be trusted, because chances are that these tests were forged to produce better results, or not conducted at all. Now that you are aware of the traits that a good LED grow light should have, it is time to see how you should tailor your LED purchases according to your needs. # Size of the garden If you’ve already carried out indoor gardening, you would already know the concept of space. If not, simply measure out the length and breadth of your indoor growing area (for choosing the growing area, see next section) and figure out how many plants you will be using. Based on this estimate, decide the wattage and the number of bulbs that you would require. In case, you are upgrading from HID lights (as a vast majority of growers and horticulturists are doing), the following quick reference table may be helpful.
|HID Wattage||LED Wattage|
Each plant has its own vegetative and flowering phases, and needs specific conditions for growth. As a grower, it is your task to figure out how the plants will grow efficiently (though for the average case, we have provided some growing tips in a later section). Once you have figured out your optimal plant growth conditions, you can purchase the LED lights accordingly, keeping in mind the thumb rule that it is always better to go for specific wavelengths rather than a full spectrum white LED light.
Getting Ready To Install LED Grow Lights
Now that you know how to choose the best LED grow lights, it is time to find out how to install them. Before you head to Amazon to purchase them however, you need to get your “grow room” in order (assuming of course that you’re going in for small-scale indoor growing, commercial greenhouse growing parameters are different). On the other hand, if you’re already a seasoned grower who is planning on simply switching to LED grow lights, you may skip this section.
Grow rooms are areas where plants are grown indoors. While some expert growers use special tents and greenhouses, they are neither necessary nor indeed the most efficient. Rather, some of the most efficient indoor growing areas are basements, closets and attics. Most houses have such areas, and if used skillfully, they can become permanent spaces for indoor growing. However, there are a few factors that need to be kept in mind when choosing a certain area (or transforming an existing space into a grow tents).
- Temperature – It is a no-brainer that extreme heat or light will kill your plants. However, even subtle changes in temperature can make a great difference between a good tasting plant and a not-so excellent end product. Generally, plants are capable of handling a decent range of temperature, so you don’t have to worry about keeping them “warm”. However, during the “day” ie when artificial lighting is being used, you should measure the temperature to find out if temperature is exceeding the prescribed temperature. Though this is not generally an issue with LED lights, trying out a few normal home LED lights in the space for a few hours can give you a good idea before you go in for extensive purchases.
- Humidity – A minimum level of humidity is required to ensure that plants take up nutrients at a rate sufficient for them to grow adequately. However, humidity should not be too high, or parasitic organisms (like mold and fungi) which thrive in high humidity can erupt, proving detrimental to the health of the plants. Indeed, humidity is especially important if you’re going in for hydroponics, or the growing of plants in water.
- Air Circulation – Ideally, the grow room should not be exposed to direct wind, since these can cause frost or dryness to develop in the plants. However, a decent air circulation should be maintained, preferably through vents, so that there is never an excess of oxygen (during photosynthesis) or carbon dioxide (during respiration).
- Electrical Connectivity – LED lights do not demand an excess amount of electricity, and can run fine on existing circuitry. However, as we noted above, they do require heat sinks, and provision has to be made for them either inside the grow room, or more ideally, outside. Furthermore, while installing the LED lights, you should make sure that the anticipated load is not too high, or you may find trouble arising with the overall electrical phase of your house. Generally, growers use these lights during the nighttime, when the overall usage of electricity in the house is low, and switch them off when demand is at its peak. Plan out a schedule according to which the activities of the house will not clash with indoor growing. Finally, once you’ve started out, you can consider purchasing a generator to act as a fail-safe if your area suffers from frequent outages.
Preparing the Floor Plan
In the section above, we saw that deciding the approximate growing area was vital for choosing the right quantity of grow lights. Before installing them, however, you need to find out the exact layout, which is often called the “floor plan”. Decide where what type of plants will sit, and where the lighting, the fans, the water supply (in case of hydroponics) and the gardening supplies will go. Since LED lights do not make for diffuse lighting, the areas to be covered by LED lights should correspond exactly to the areas in which plants will be kept. In other words, do not allocate plants to areas which may receive peripheral lighting, unless you are willing to compromise on the overall quality of the produce. Furthermore, while choosing the lighting, ensure that there are enough fans – both exhaust and indoor – installed. Finally, never make the mistake of adding additional plants after you’ve prepared the floor plan. You may add additional lights or fans, however, depending on the needs of the existing number of plants.
Setting Up Insulation
Lucky is the grower who is gifted with a growing room possessing all of the parameters mentioned in the “Choosing the Growing Room” section in perfect quantities. More often than not, the problems of moisture and/or privacy have to be tackled, and if this is the case, it is wise to go in for wall insulation. Wall insulation is of several types, and while a guide to choosing wall insulation is beyond the scope of this guide, it is worth mentioning that for our purposes, the ideal wall insulation would be one that does not interfere with the existing wiring of the walls. Furthermore, if your wall has a lot of pores through which air normally comes in, insulation will close these off and can potentially create air circulation and temperature issues that would require additional vents and fans. If you’re going in for hydroponics, however, you will need to install a watering system that may need to go through the same walls that need to be insulated. In such cases, postpone insulation till after your plumbing is complete.
Air Circulation System
You’re probably getting impatient, wondering when the actual installation procedure will be explained. We’re one step away from that step, and the step that stands between is installation of intake fans and exhaust. We mentioned adequate air circulation as one of the critical points to keep in mind when choosing a grow room. While some amateur growers have succeeded without using special air circulation methods, their numbers are very low. Ideally then, one should have an air circulation system composed of air intake and expulsion units. Given the dynamics of air circulation, the ideal air intake unit should be located near the floor, while the expulsion unit should be located near the ceiling. In case you are using an attic or basement, it would be wise to remember that the expulsion or exhaust unit should never be at the same level as the plants, since this tends to create imbalances in the relative availability of CO2 and oxygen. Furthermore, it is also vital to remember that the exhaust fan should ideally be larger than the intake fan. This makes sure that the original flow path of air, from lower areas to upper areas, is followed in the grow room. If you like, you can choose to cycle air using an air recycling unit or draw in air from outside. The pitfall with the latter is that it introduces potentially hot or cold air into the atmosphere. The benefit, at least in the initial stages, is that you don’t have to spend the additional funds required to buy a recycling unit. Either way, it is wise to ensure that the air flows in and out at least 30 times per hour.
Installing the LED grow lights
Considering all the preparation that goes into installing LED lights, the actual procedure may seem to be disappointingly short. Firstly, the LED lights have to be purchased from either a local departmental store, or if you want a better range, online stores like Amazon. If you’re new to growing, it is important to know that the ideal amount of lamp power required of HIDs for 6 feet is around 600W. However, given that we are dealing with LEDs here, the figure will naturally be much lower. But luminosity and wattage don’t have a linear relation Unlike HIDs, where a fall in wattage directly reduces luminosity in about the same proportion, LEDs tend to grow dimmer but not by that much. The reason is that as the wattage rises, the efficiency of the LED tends to fall, though again not in any direct proportion. A 3W LED will be less efficient than a 1W LED, and while the former will of course be brighter, it won’t be three times as bright. Hence, if we take it as a rule of thumb that LEDs are 60%-75% more efficient than HIDs, we still can’t just use any combination of LEDs that total up to a wattage that is 25-40% of the HIDs’ wattage. Instead, we should follow the recommendations given by well respected companies (or reputable reviews of the products) to figure out the actual number of bulbs. As the example tells us, large numbers of lower powered LEDs are better than few high powered LEDs. Hence, while buying LEDs, it is vital that the number of LEDs be high and their individual wattage be as near the 1W mark as possible.
The inverse square law
According to the inverse square law, the intensity of light incident on a surface rises exponentially as the distance is reduced. In terms of growing, this means that if a plant received 40 lumens of light at 2m distance, then it would receive 160 lumens of light at 1m distance. Since LEDs do not exude heat into the surroundings, they can be brought within a meter of the plant surfaces, and at this distance, they allow the plant to take in a much higher amount of light without burning the leaves. Hence, you may want to install the lights at 1m distance or even less, and so make considerable savings in terms of lights purchased to produce adequate luminosity. On the other hand, if you have purchased LED lights without consideration for this factor (or later realize that you can safely take the lights even closer), the amount of LEDs so saved can be used to expand the growing area, preferably in a new grow room. Fitting and running the LED lights
Once you have decided the number of LED lights required based on the above factors, you can buy them and get ready for the final step – installation. Since you’ve already figured out where to install the lights (refer to “floor plan” step above) all you have to do is attach the lights at the correct places, connect the wiring and place the heat sinks in their correct positions. Make sure there is no hanging or damaged wires, since the lights will be used for long hours and substantial heating are involved. Further, ensure that the wires are not installed in a manner that impedes normal human movement; otherwise you may trip on a wire and wreck your perfect LED setup. Finally, make sure that the wiring involved does not wreck your insulation. Once the LEDs are correctly installed, run one or two arrays to see if they are working properly. If they are, keep them on for a few hours, and then turn on the remainder of the arrays. If possible, test the system this way for the expected duration of the “day” you wish to create. We know that the few arrays you turned on at the beginning will run longer than is usually necessary, but this helps test out the general efficacy of the circuit as well as the general build quality of the LED grow lights. Once these tests are complete, you can introduce your plants, fit in the watering systems (if any) and begin your career as a grower!
Safety Precautions for LED Grow Lights
Like all electrical appliances, LED light arrays are also prone to produce health risks if not handled with adequate care. Thankfully, handling LED lights is far easier than handling some other types of lights that may be available at a grow lights sale in online or brick and mortar portals. Still, it is better to be safe than sorry by using some basic safety precautions. # Keep wiring away from water While you may follow this age old rule for every other type of wiring in your house, you should be extra careful in your indoor grow room because here there will be constant use of water. Contact of water with electricity leads to not only electric shocks, but also damages the electrical wiring, even if the water does not reach the internal circuitry of the lamps themselves. To be water-safe,
- Keep the bulk of wiring near the ceiling, preferably where there is little dampness or water leakage.
- It may not be possible to keep heat sinks in such high areas (without extensive use of attachments and fixtures). Instead, they should ideally be kept in an adjacent room (where there is no water involved) or placed in areas that are sealed off from the water channels.
- Ensure that reservoirs or pipes do not have any cracks or leaks that may inadvertently cause water to flow out from the leaks and reach the wiring. This is especially important when you’re using hydroponics.
# Bundle up Your Wiring A small indoor garden with few LED lights has few lines of parallel wiring, and is therefore not something difficult to handle. As you go on adding LED lamps and other electrical appliances, however (air recyclers, CO2 machines, etc) there will come a time when there will be a jumble of wiring running in all directions, blocking free movement and creating the risk of fire. To avoid this, it is advisable to bundle the wires together with electrical tape and run them across the higher parts of the room in a manner which ensures minimal branching out, at least in the main grow areas. # Check new products for damaged wires LED lights bought online from shady dealers may in themselves be of good quality, but they may be second hand, or they may use second hand wiring to cut costs. The result is in many cases the presence of wiring that is torn or otherwise damaged, held together by weak electrical tape. Though such wires may be in a minority, it is better not to take a risk with the whole product, since damaged wires increase the risks of fires, shocks and short circuits significantly. Instead, the wires should be properly sealed and insulated. Now while it is possible to insulate wiring manually (or repair it if it is broken), the complexity of the wiring associated with modern LED panels makes it a tiring and self defeating task. Instead, it is better to go in for products that have a verifiable warranty, and to get them changed if the wiring appears dubious. # Don’t run LED lights for too long Only seedlings benefit from round the clock “days”, and this phase is at best transient. Keeping lights on all day not only wrecks the lifecycle of the plant, it also wrecks your budget. More worryingly (for your safety at least), it also exposes the LED wiring to high levels of heat for long periods of time. Now while LED lights produce lesser heat and can run longer than the competition, they are not immune to heating, and no matter how good a heat sink you use, the heat will eventually build up and begin to harm the wiring. Hence, it is advisable not to run the LED lights longer than they are needed. Indeed, if seedlings need LED lighting round the clock, they can be kept under one set of LED lights for a certain period of the day, and under another for the remainder.
Growing Tips for Your Indoor Grow Room
Though providing a full length growing guide is beyond the scope of this guide, we can mention a few useful tips to keep in mind as you embark on your journey as a grower using LED lights. Don’t Change the Method of Cultivation Midway Many amateur growers realize their mistakes when the plants are already 4-6 weeks old, and there is no way to correct them. They therefore search frantically for “corrective” methods and apply them indiscriminately, thereby ruining the plant’s lifecycle entirely. While it cannot be denied that corrective methods do exist for various stages, they are usually limited to changing the environment and not the method of growing. Any guide that tells you to change the method or trigger any other major change is likely written by folks with little experience in the industry because once the plants have begun to grow, the hormonal cycles have already begun and massive changes can only be disruptive to such cycles. Therefore, it is better to either terminate the growing entirely or make minor changes in order to complete the growing period and analyze the results thereafter. Plant Height Is Dynamic It is a no-brainer that plants become taller as they grow (barring some types of horizontal creepers). This natural tendency arises from their attempt to reach out towards the source of light, so depending on the height at which you keep your light, your plants can become short and stubby, of correct height or tall and lanky. Whatever the height finally achieved though, remember to adjust the lights accordingly, because what may have been optimal height for the plant at say 2 weeks would be too close at say 5 weeks. Don’t overdo the nutrients Nutrients are vital to plants, but excessive nutrients can retard growth. Typically, LED light systems require that you provide plants with about 25-30% less nutrients as compared to HID systems, due to the better rate of photosynthesis achieved with the latter. If you’ve been using HID grow lights, it is highly recommended that you factor in this reduction (and by the same token, cost reduction) when shifting to LED lighting. Growing Is A Daily Chore Many amateur growers spend a huge amount of time setting up and admiring their grow room only to forget about it after a few weeks. Just like scheduling of electricity usage, you should schedule your time so as to spend at least an hour a day watering your plants and checking for problems. If you cannot do so, it would be great to hire a professional to take care of the plants. Agreed that this may not be the most interesting of tasks (apart from the sheer pleasure of watching the plants grow) but it can alert you of potential dangers such as pests, growth inhibitors and suchlike before they ruin your crop.
While opinions may differ as to how effective the LED revolution will be, more and more experts are agreeing that as far as LED grow lights are concerned, the revolution will be highly effective, eventually leading to the withdrawal of older HIDs from most indoor grow rooms. While earlier grow lights offered one or two advantages along with numerous disadvantages, LED lights had a wealth of advantages with only one shortcoming – high cost. However, with prices falling rapidly, this shortcoming is a thing of the past. It is therefore no surprise that the LED revolution has begun to show decisive results in large commercial greenhouses, aquariums and even NASA! Even as LEDs take over, though, it is important to remember that there will always be those who try to make money through use of substandard materials and wrong information. This guide has been written to arm you with the knowledge needed to avoid such blackjacks and take the safest and most fruitful (pun intended) path of indoor growing using LED lights. Given the huge range of plants that can be cultivated using such lights, we could only be specific up to a point. Furthermore, while we have tried to incorporate the latest data in the guide, the constant evolution of the field may make this guide outdated in five to ten years. It is therefore your duty to find out the latest and most accurate information about what you intend to grow. That said, this guide does try to provide the latest available information in a lucid format, and based on our own experiences, we can say that the if followed properly, can provide you with one of the easiest ways in which to go about the task of setting out to grow indoor plants. Whether you be a budding commercial grower, one who wishes to take up growing as a hobby or one who needs to grow plants as a backup food source in remote and/or cold areas, we wish you the very best in your endeavor to add some more greenery to the face of this planet. Happy Growing!
LED terminology can be confusing at times, so if you’re stuck wondering what a certain term means, the following short list should give you a helping hand: A Ambient Temperature – The air temperature around the device when it is in “on” state American National Standards Institute – An American organization that develops standards and benchmarks for a wide range of products, including LED lights. Ampere – The metric unit for measuring the rate at which electric current flows through a body B Brightness – Defined as the number of photons hitting a certain area in a second, brightness is a measure of the ability of a light source to produce light energy. Black Body Curve – A graph that defines the sequence of colors of light emitted by a black body radiator in a given color space. C Chromaticity – The saturation of a color measured independent of its luminance. It defines the quality of the color rather than the intensity of the light. CIE 1931 Color Space – Defined by the 1931 International Conference on Illumination as the whole range of colors visible to the average human eye. CIE Chromaticity Diagram – A line that connects the chromaticities of various colors of the light spectrum. It is a horseshoe shaped line. Color Model – A model used to show colors as values for mathematical operations. RGB (Red Green Blue) is the most famous color model. CYMK or Cyan Yellow Magenta Key (Black) is another model. Color Rendering Index – Abbreviated as CRI, Color Rendering Index is a measure of the shifts undergone by the colors of an object as compared to those undergone when it is illuminated by a reference light source. Color Spectrum – The spectrum of electromagnetic radiation that we can see, and which is generally referred to as the light spectrum. It has a span between 390nm and 750nm. Lower than 390nm lies infrared rays (heat) and higher than 750nm lies ultraviolet (UV rays). Correlated Color Temperature – The temperature (measured in Kelvin or K) of a black body which is emitting radiation of the same chromaticity as the body under investigation. D Die – The chip on which the semiconductor diode sits. Directional Light Source – A light source that projects light only in the direction which it is facing. Driver – The circuitry involved in running illumination sources. (referred in context of driver circuit in the guide) E Efficacy – The light output of a source divided by the total power provided to the source (also referred to as efficiency in the guide). G Ghosting – When the light is switched off but still glows faintly, it is called ghosting. It is the result of residual voltage remaining in the bulb. Goniophotometer – A measuring device used to measure luminous flux, efficiency and intensity distribution. H Heat Sink – A thermal component that takes away heat from the sensitive circuitry of LEDs. High Power LED – An LED that has a power of 350mA or higher. All LED grow lights are high power LEDs, since the minimum expected power of a lamp is 1A. Hot Testing – LED testing at a temperature of 85 degrees C or higher. I Illuminating Engineering Society of North America – A group that is regarded as the authority on lighting standards in North America as well as in other parts of the world. InGaN LED – Made of Indium, Gallium and Nitrogen, InGaN is the preferred LED for blue light LED lights. J Junction Temperature – The temperature at the p-n junction of the LED K Kelvin Temperature – The color of a light compared to a theoretical blackbody. Expressed in Kelvin (K). L LED Driver – The circuitry that converts the input AC power into the DC power needed by the LED. It protects against fluctuations and surges as well. LED Light Engine – A complete solution that offers a LED array (or single lamp), driver circuit and other important lighting or non lighting components. Lumen – The SI unit of luminous flux, measuring the amount of light falling on a square foot of area. Luminaire (also LED Luminaire) – A LED fixture that is complete with all necessary parts. Luminous Efficiency – The total lumens emitted by the light body minus the wasted or blocked lumens. M MCPCB – The special space-grade technology with Metal core used for making circuit boards. N NTSC Color Space – The part of the CIE Color Diagram obtained when RGB phosphor sources is utilized in CRT applications. O OLED (Organic LED) – Made of carbon molecules instead of doped semiconductor materials, OLED is made in sheets that ensure a more diffuse light range. P Phosphor Conversion – The process by which the photons of one light color are converted into those of another light color. Pulse With Modulation (PWM) – Used for dimming purposes, PWM turns LEDs on and off at a very high frequency, which due to visual retention by the human eye, gives the impression of a dimmed light. R RGB White – The method by which white light is produced by combining the components of RGB spectrum. S Solid State Lighting – Defined as the light sources which do not have movable or breakable parts that may detach and contaminate the environment. Steradian – A measure of two dimensional angles in three dimensional space. Substractive Color Model – Mostly used for dyes and paints, SCM is usually used to produce black color from subtraction of red, blue and green lights. T Thermal Resistance – The ability of a body to conduct or retain heat within oneself. Tunable White Light – White LEDs with alternate cool and warm LED light channels for producing a better range of color temperatures. U Useful Light – The amount of light a lamp delivers after subtracting the waste light. V Volt – The electrical potential difference between oppositely charged conductors. W Watt – The amount of electricity consumed by a body during operation. It is the standard power usage unit of a body.