P.L. Light Systems’ HortiLED series of grow lights meets the requirements of controlled environment agriculture

Whether greenhouse, vertical farm or warehouse growers are propagating or producing ornamental, vegetable or cannabis crops, P.L. Light Systems offers the LED fixtures to meet their lighting needs.

P.L. Light Systems develops and manufactures supplemental lighting systems for the horticultural industry. The nearly 40-year-old company manufactures traditional light sources, including high pressure sodium (HPS) and metal halide, as well as its own light emitting diode (LED) fixtures.

“There are a lot of lighting products hitting the market right now, especially when it comes to LEDs,” said Eric Moody, P.L. Light Systems western USA Lighting Solutions Specialist. “The future of the horticultural lighting market is moving toward LEDs as the technology continues to advance. Every week it seems like there is another company entering the horticultural lighting market. Growers need to carefully look at the lighting companies they are considering working with. How long has a company been around and is it focused on horticulture or is it just buying circuit boards and selling them as LED horticulture lights?”

Even though P.L. Light Systems has been marketing horticulture grow lights for nearly 40 years, it was not one of the first companies to offer LED lights. “One of the reasons that we weren’t one of the first companies is because of the intensities and efficiencies of LEDs,” Moody said. “In 2014-2015 the market started to see LED diodes that could deliver 2.1 micromoles per joule (μmol∙J–1). When this occurred everyone that was selling LEDs to the horticulture industry got excited.

“Double-ended HPS lamps that are used in horticulture put out 2,100 micromoles per 1,000 watts, which is 2.1 μmol∙J–1. So what happened is LEDs finally equaled HPS. LEDs didn’t surpass HPS. When this happened P.L. started looking into the LED market and to surpass what was available.”

P.L. Light Systems’ HortiLED TOP and HortiLED INTER fixtures are finalists in the Horticultural Lighting Category for LEDs Magazine’s 2017 Sapphire Awards. The awards will be presented March 1, 2017, in Anaheim, Calif.


P.L. Light Systems HortiLED TOP

P.L. Light Systems HortiLED TOP light is a fully enclosed fixture with an integrated driver that delivers 2.7 μmol∙J–1. The TOP fixture measures 38 inches long by 4.7 inches wide by 3.7 inches tall and weighs 18 pounds. The fixture is available in two distribution angles, 80º and 150º, and light spectrum of red/blue, red/white, full spectrum and customized.

“P.L. started in the greenhouse market so we are catering to that segment of the market even though there are a lot of indoor growers using our fixtures,” Moody said. “We want to be sure everything we manufacture is able to be used in a greenhouse.

PL Light Systems HortiLED toplighting

“The TOP fixture drivers are driving the diodes to 2.7 μmol∙J–1. But the diodes we are using are capable of going above 3 μmol∙J–1. We are driving our diodes to a lower percentage because we don’t want to overheat them and we want them to last for 28,000 hours. We are better able to control the heat by not overdriving the diodes. Our goal is to have totally passive cooling so the fixture can be hung right up under a truss and it is fully enclosed.” Moody said having a totally enclosed fixture offers an advantage over other toplight LEDs on the market.

“Other manufacturers are either installing fans in their fixtures or they are mounting the drivers separately,” he said. “The LEDs with fans built into the fixtures can suck in dust and insects. These fixtures can short out because they get a build-up of debris inside the fixture. The fans push air across an electrical circuit board. There are also water-cooled fixtures. There is a water line running from one fixture to the next.

“Other manufacturers’ fixtures are large units in order to get the light output. These fixtures might work for some indoor growers, but they’re not going to work in a greenhouse. These larger fixtures reduce the amount of sunlight reaching the plants by casting shadows over them.”

Moody said with LEDs the light is very directional so it doesn’t cover as big of a footprint as HPS.

“We offer two TOP light LEDs that have different distribution patterns,” he said. “It’s not a reflector, it’s the diode itself. We have an 80º diode which is very common. This fixture puts out an 80º wide distribution pattern. We also have a 150º diode that puts out a much wider distribution pattern. This enables us to cater light plans to the growers’ crops. It offers a lot of room to move up and down depending on how far the fixtures need to be from a crop.”


P.L. Light Systems HortiLED INTER

The HortiLED INTER fixture is made for tall vine vegetables, ornamentals and some cannabis production. “The fixtures are mounted down the center of the crop,” Moody said. “It is supplementing the light that is being received from above the crop. For a 14-foot tall greenhouse tomato crop a grower may have HPS or LED toplights above and then the interlights below. Sometimes growers will use two rows of interlight fixtures in order to get more light deeper into their crops.

“The INTER fixture has the same high output diode as our TOP fixture, but because of the cover on the INTER fixture, the output reaches 2.5-2.6 micromoles per joule depending on the light spectrum.”

The INTER LED is a fully enclosed fixture equipped with a polycarbonate cover that keeps it totally waterproof. Moody said this ensures that the fixtures are not affected by high humidity environments, mist systems and spray applications.

The INTER fixture measures 48 inches long by 2.2 inches wide by 4.8 inches tall and weighs about 4 pounds. The fixture operates with an external driver and is available with a red/blue spectrum.

“With an interlighting fixture hanging in the crop, the light distribution pattern should go out to the sides hitting all of the leaves that are around the fixture,” Moody said. “Our INTER fixtures put out what looks like a butterfly wing pattern. The light pattern goes out sideways, but at the same time it also goes down. We use reflector technology to direct the light.

“The INTER fixture has one bank of LEDs. Some other interlight fixtures are larger and heavier units because they have two LED circuit boards back-to-back putting light out on each side of the fixtures.”

Eight of the 4-foot INTER fixtures can be run together using one driver. Moody stated interlight fixtures need to be lightweight because growers hang them on crop wire or whatever is being used inside the crop.

The INTER fixture is not yet available for the U.S. market. “We are still finalizing our UL listing in the U.S. for the INTER fixture,” Moody said. “This fixture is available in the red/medium blue spectrum. The INTER fixture is expected to be available for the U.S. market by the end of the first quarter.”


P.L. Light Systems HortiLED MULTI

The P.L. Systems HortiLED MULTI fixtures are being used primarily for propagation, young plant production and vertical farming.

“Just like with the TOP fixtures, our MULTIs are available in 80º and 150º distribution outputs,” Moody said. “We also have two different lengths, basically a 4-foot (122 cm) and 5-foot (152 cm) fixture. These fixtures have an integrated driver and are available in low and high output versions. There are some applications where a low output is needed, better uniformity, closer to the crop like with tissue culture and early plant propagation applications. The high output fixture is for later in propagation or for propagation of bigger plants. For the MULTIs we can do numerous light spectrum combinations.”

Moody said the MULTI fixtures are ideal for vertical farming applications. “We can do vertical growing with lettuces, mixed greens, microgreens, all of those under these lights as well. Our MULTI lights have a higher output than most other LEDs used for this application.


“For propagation most growers use multiple layers. Typically they are built with two to four layers on racks. The MULTIs were designed to be installed on the underside of a rack pointing down toward the crop below it, from 9 inches to as far away as 2 feet from the crop.”