High-pressure sodium (HPS) lighting was long considered the industry standard when it came to lighting indoor and greenhouse controlled environment agriculture (CEA) applications. So ubiquitous was the usage of HPS that many greenhouse and indoor setups were designed specifically to accommodate the lighting system, accounting for the radiant heat generated by HPS bulbs and ballasts.
As light-emitting diode (LED) lighting has taken the horticultural world by storm over the past five years, it has become undeniable that it boasts many advantages over HPS lighting. In addition to producing less heat per photon of light, LED grow lights utilize electricity more efficiently and offer greater environmental control than their HPS counterparts.
Along with these advantages come added benefits for the cultivator, namely reduced energy costs and reduced maintenance costs while increasing yields. The economic viability of LED lighting systems is becoming increasingly apparent as time goes on, yet questions remain.
As many horticulturalists consider making the transition to LED grow lighting, they’re faced with a host of decisions and factors to consider. Here, TSRgrow offers answers to many of these questions, such as:
- What advantages do LED lighting systems possess over HPS lighting systems?
- How does TSRGrow’s Remote Power Server Technology impact grow environments?
- Is a one-to-one HPS to LED light swap a viable option?
- What are the advantages of a full, professional system replacement?
- How can TSRGrow’s proprietary technologies help to generate the highest possible yield at the lowest possible cost?
LED vs. HPS grow lights
The first and most-discussed difference between HPS and LED lighting is the energy consumed by each. Studies have shown that implementing LEDs in an operation previously lit by an HPS system reduces lighting energy consumption by between 40-60%.
However, added control over the environment, as will be discussed, also saves growers on other costs, such as HVAC and CO2.
HPS fixtures and heat
Probably the most significant variable in working with HPS grow lighting is the dramatic temperature fluctuations created by the bulbs and ballasts. Because HPS grow lights emit around 80% of their energy as radiated heat, they naturally warm the grow space in which they’re being utilized. Surface temperatures of 750°F are not uncommon with HPS bulbs.
In addition, the ballasts required to power HPS bulbs require tremendous amounts of energy upon startup and generate large amounts of heat in the grow space. Between the radiant heat from the bulbs and the additional heat produced by the ballasts, HPS fixtures generate enough heat to alter the environmental conditions of a grow space drastically, requiring significant HVAC to cool and maintain the ambient conditions.
Mitigating heat in HPS environments
The high temperatures produced by HPS lights require mitigation in a CEA facility. Most often, this is achieved through extensive HVAC cooling or venting, requiring additional energy costs. Moreover, the heat produced by HPS systems can damage plants in several ways, such as stunting growth, drying out the grow medium or complete crop failure.
Many indoor and greenhouse growers who began with HPS lighting learned to account for the heat that would be generated by the bulbs and ballasts. Growers in cooler and more moderate climates have, for decades, made use of the heat to maintain temperatures as near to optimal as possible. Even still, temperatures fluctuate significantly once the lights go off for the night, requiring additional heating in colder climates and, thus, greater energy consumption.
Unfortunately, even in colder climates, much of the heat produced by HPS systems must be vented or otherwise circulated via HVAC to prevent temperatures from reaching damaging levels and preventing plant leaf surface temperatures from getting too hot. Because HPS systems are less efficient at converting electricity into light - most of it is radiated as heat - operating an HPS system requires the grower to accept as a given, a certain amount of heat as waste.
Reducing thermal waste with LEDs
LED grow lights, by contrast, operate at significantly lower wattage, producing between 30% and 50% less heat while producing equal to or more photons. As LEDs are semiconductor devices, their efficiency, lifetime and operation is driven by their operating temperature - the cooler they are kept the longer they last. To keep them cool, heat sinks must be employed to conduct heat away from the LEDs and convert them into the air. HPS bulbs, on the other hand, are designed to operate at high heat as they light with a burning gas inside. This heat radiates out of the front of the bulb, affecting the plants directly below them. LED grow lights produce significantly less heat, and the heat they produce is conveyed upward and away from the plants, not directly onto them, as with HPS lighting.
Because LEDs generate less heat, temperature fluctuations are less frequent and less dramatic, offering the grower significantly more control over the conditions within their environment.
Most significantly, transitioning from HPS to LED lighting will result in a reduction in thermal waste and reducing the amount of venting cycles - helping maintain ambient temperatures, reducing the need for extensive HVAC usage.
HPS lighting has long been beloved for the spectrum it produces, which is heavy in yellow and red light and thus is beneficial in initiating flowering. However, the spectrum is also one of its drawbacks, as it actually is limited with its range of spectrum available for plants, particularly valuable blue light.
Because of their limited spectrum, HPS bulbs have long been used for flowering, though their lack of blue light makes them less favorable for vegetative growth. As a result, many growers have implemented other bulbs, such as metal halide bulbs, during the vegetative stage. While this bulb swap has proven beneficial for achieving an enhanced spectrum, it adds yet another step and increased maintenance costs to the bottom line.
LED grow lights, by contrast, offer growers a much broader spectrum of light. Because LED grow lights are comprised of many smaller diodes, manufacturers can manipulate the spectrum produced. This has enabled LED producers to create lights that much more closely resemble the full spectrum of the sun, leading to more increased yields.
Dimming for increased control
LEDs also benefit from greater dimming capabilities. HPS lights can be dimmed by making adjustments to their controlling ballasts but operate at much lower efficiency when dimmed - and the dimmability range is limited, typically less than 50%. HPS systems struggle tremendously to offer accurate supplementary light in greenhouses, namely as a result of the lack of dimmability of the fixtures. Most can only dim to 50% - and even though they can dim slightly, the response time is slow to turn on and dim up or down. Additionally, dimming wires would have to be run to each fixture, so most installations just have an on/off cycle. This wastes a significant amount of energy and provides for limited control over the lighting in the grow area.
By comparison, LED lights typically incorporate dimmable drivers/ballasts with built-in dimming features. Dimming LEDs allows growers to use them as supplementary light in greenhouse applications at a minimal cost and apply sunrise/sunset and other lighting profiles to the grow process. The enhanced dimming functions of LED grow lights also enable growers to reduce the intensity of the light to replicate the changing conditions of the sun at any time of year, both saving energy and creating more favorable growing conditions.
Greater environmental control
The heat produced by HPS systems necessitates additional cooling to avoid reaching excessive temperatures. This additional temperature regulation requires added regulation of the other conditions within the grow environment including relative humidity (RH), vapor pressure deficit (VPD), and CO2 levels. As a result, all of these conditions must be restored through their respective systems, all adding to the total expenses.
The lower temperatures produced by LED grow lights mean better control of the environment in the grow space reducing HVAC costs. Though LED growers may have to supplement heat in cooler climates, the savings on electricity typically more than offset heating expenses.
Some shared problems
While LEDs have proven themselves more efficient in nearly every measure, there is one major design flaw that the majority of LEDs have carried over from their now-dated HPS counterparts: ballasts.
Used to regulate current and voltage supplied to the lamp during start-up, and throughout operation, ballasts/drivers are an absolute necessity for HPS and other high-intensity discharge lighting. Without them, lamps continue to increase their draw of electrical current until they burn out, which, without a ballast, takes only seconds. Unfortunately, ballasts are also the most likely component of a lighting system to fail.
LED grow lights still make use of ballasts/drivers, despite many companies’ claims that their lights operate without them. In commercial settings, ballasts/drivers are necessary to handle the electrical load. Thus, many of the same problems which exist for HPS growers still come into play for LED growers: accessing damaged or failed ballasts/drivers suspended over a maturing canopy can put the entire crop in danger, create additional maintenance costs and most importantly, impact the grow environment. Additionally, to realize any dimming features, dimming wires must be run to each fixture in order to dim and control them. This adds significant cost and inefficiencies in installation and startup - as many times dimming zones are limited to 1 or 2 per room to minimize wiring and installation costs.
Ballasts/drivers, heat and weight
Ballasts/drivers generate significant heat on their own, regardless of the type of light they’re powering. While LED grow lights do not produce anywhere near the radiant heat that HPS lights do, the ballasts/drivers which are used to control them produce comparable heat to HPS ballasts.
Most LED grow lights feature between one and five local ballasts per fixture, and the typical lighting ballast weighs between three and ten pounds. That’s a whole lot of additional weight being suspended above the canopy, weight which will also require costly hanging measures.
Ballasts are also limited by their two-wire 0-10V dimming connection, which requires each fixture to use an additional Y cable or RS485 junction connection to sync multiple fixtures. This makes it particularly difficult to achieve control over individual zones, as all fixtures must be synced together.
TSRgrow's advanced LED lighting
"TSRgrow’s Advanced LED Lighting System begins with reimagining the solution to your lighting needs. Our TOTALGrow Solution offers the grower maximum control over their lighting unlimited built in zone and lighting control, remote power servers, ballast-free fixtures, easy installation and simplified maintenance. In addition, our advanced LEDs offer a full-plant-spectrum and full integration with our GROWHub environmental monitoring software."
"Our full-plant-spectrum LEDs can be customized to fit any grow environment, whether indoor, vertical or greenhouse. We offer a range of versatile fixtures that can easily be adapted to suit any need, and because they are powered by remote ballasts, the positioning of lighting can be fully customized."
Remote power server technology
"At TSRgrow, we’ve been working for years to refine horticulture LED lighting technology to its absolute pinnacle. As such, we’ve developed critical insights into the issues facing growers, how they can best be mitigated, and solutions for any and every problem that may arise."
"We began with lighting. We long-ago recognized the tremendous benefits of LED lighting in CEA environments but also recognized that many of the same issues which had plagued HPS growers still remained. Chief amongst these was the issue of ballasts, ballast heat, and their control."
"TSRgrow advanced LED lighting solutions are truly de-coupled from the ballast/driver. We’ve completely removed the ballasts from our grow lights and replaced them with remote/centrally-located power servers. Located outside of the grow room in server cabinets, access to them is quick and simple. Should a grower experience a power failure, remote diagnostics quickly identify the issue - and if a power module swap is required, it’s as simple as opening a cabinet to replace it rather than dangling precariously over the canopy and potentially introducing contamination. Furthermore, our GROWHub environment monitoring and control software offers the grower infinite zone control over every aspect of their grow room’s lighting. Implementing our GROWHub software means no more dimming wires, contactors or relays, making installation and maintenance as simple as possible."
"In addition to making access easier, our remote power server technology also allows for greater versatility in mounting or hanging lighting. De-coupling the driver from the LED fixture enables us to deliver the power and photons to fixtures based on the desired PPFD and light mapping desired by the cultivator. In addition, our ballast-free LEDs are easily daisy-chained as our plug and play setup simplifies installation altogether."
Transitioning to LED: Existing facility
One of the most common questions growers have when it comes to making the leap into LED lighting is whether they can complete a simple one-to-one swap of their HPS fixtures for LEDs. While the short answer is yes, it is possible, the reality can be a bit more complicated.
As long as LED grow lights have been in existence, manufacturers have made “equivalency” comparisons, stating, for example, that their 600-watt LED lights are the “equivalent” of a 1,000-watt HPS light. While this may be true in some sense, such as PPF or DLI, it’s only a portion of the story.
The loss of heat from HPS lighting will inevitably result in the increased usage of HVAC and other systems. Being that many growers design their operation around their lighting sy
stems, these other systems will quickly prove inefficient when coupled with LED lighting. HVAC loads, for example, are altered drastically as venting, and cooling cycles are rarely necessary when working with LED lighting, particularly TSRgrow’s ballast-free LED lighting.
It is often the case that other solutions, such as thermal heating, may be more prudent for those adopting LEDs than relying on their existing HVAC system. Depending on the type of operation and its locale, cooling and venting may have to be replaced by heating, as ambient temperatures under LED grow lights will inevitably be cooler.
The idea of saving a quick 40% on lighting costs is appealing, but it doesn’t account for all energy that will be used to maintain ideal conditions. When transitioning existing facilities from HPS to LED, it is important to consider all these factors in the changeover.
Transitioning to LED: New construction facility
TSRgrow's advanced LED lighting solution
"Our advanced LED lighting solution begins by reimagining the solution to your lighting needs. Our TOTALGrow Solution offers the grower maximum control over their lighting with advanced lighting and zone control software, remote power servers, ballast-free fixtures, easy installation and maintenance. In addition, our advanced LEDs offer a full-plant-spectrum and full integration with our GROWHub software."
"Our full-plant-spectrum LEDs can be customized to fit any growing environment, whether indoor, vertical or greenhouse. We offer a range of versatile fixtures that can easily be adapted to suit any need, and because they are powered by remote ballasts, the positioning of lighting can be fully customized to your facility."
Remote power servers
"We incorporate our remote power servers into our professional system replacements, eliminating ballast heat and maintenance in the grow room. As a result, our grow lights impact the grow environment very little, offering the grower total control over grow room conditions, all of which can be monitored via our GROWHub software."
GROWHub lighting, scheduling and zone control
"Our proprietary GROWHub software effectively removes all guesswork from the growing process, especially when it comes to lighting. GROWHub not only controls lighting timers, but is also capable of handling a multitude of dimming functions, enabling control of multiple zones from one central locale."
"By enabling infinite zone control, GROWHub enables growers to easily cultivate multiple strains alongside one another without any physical barrier. Instead, each strain receives its preferred and most productive light settings, including intensity and spectrum. These settings can then be saved for easy replication at a later date. Best of all, our plug 'n play grow lights make installation and maintenance a breeze, removing dimming wires, contactors and relays from the equation entirely."
GROWHub environmental monitoring software
"Our GROWHub environmental monitoring software is an integrated automation platform designed to monitor, analyze and control lighting and other growth parameters. Syncable to tablets, smartphones and computers, GROWHub is capable of controlling compatible light fixtures, calendar-based scheduling, data logging and analysis, and full integration with systems such as CO2, air circulation and fertigation."
"Growers can utilize GROWHub software to control and fine-tune their lighting in order to optimize DLI and energy efficiency. By comparing data collected during other cycles, GROWHub can maximize all aspects of your LED system. Our GROWHub software compares data between grow cycles to determine precisely the most effective and efficient metrics. This data analysis can help to eliminate guesswork, as profitability and revenue can often be tied to singular growth parameters."
"Additionally, cultivators can control dew point, temperature, water, nutrients, CO2 and VPD wirelessly and remotely. GROWHub even alerts the grower when a fluctuation occurs, allowing the grower to mitigate any issues before damage occurs."
Facility design and analysis services
"With over twelve years of experience in the industry, our growing experts can help with grow room and system design, floor plan analysis to maximize efficiency, and ground-up implementation of our highly efficient systems."
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