Make the Switch to LED Lighting in Horticultural Applications [Part 1 of 2]

If you’re involved in the horticultural industry, listen up.

For years, high intensity discharge (HID) lamps have been the industry standard for artificial lighting in greenhouses. But recently, light emitting diodes (LED) lamps have risen to the top – and soon, LED design is expected to surpass HID lighting for horticultural applications.

Here’s why the greenhouse industry should (and likely will) make the permanent switch to LED lighting.

Why LED Lighting Will Surpass HID Lighting in the Horticultural Industry

In the past, high intensity discharge (HID) lamps have been used in artificial greenhouses because of their economic viability and their ability to provide a consistent, adequate spectrum for plant growth. Light emitting diodes (LED) lamps were not implemented as often due to early difficulties, such as cost and intensity.

Lately, that has all changed. Rapid advances in LED design and manufacturing have closed the gap to traditional discharge-based lighting technologies and are now becoming an economically viable alternative to HID sources, especially for high-value crops. In fact, some are calling this “a monumental shift.”

There are five key properties that contribute to the advantages of LEDs compared with traditional HID light sources. Although we the properties are addressed in different sections, note that they are highly interrelated and that gains in one performance characteristic will compromise others.

We’ll cover the first two properties below, and we’ll cover the the other three in our next blog post. (So stay tuned!)

For more information, you can read more about the future of LEDs in horticultural applications here, and you can read more about each of the five properties below in the “Advantages of LED Lighting in Horticultural Applications” app note.

Output Intensity of LED vs. HID Lighting

Initially, the intensity of LEDs was too low to be of practical use in horticulture, being more suited to indicator lights and control panel backlighting. The intensity of light that can now be generated by LEDs means photosynthetic photon flux (PPF) output is comparable to that of HID sources when used in clusters.

It is difficult to compare the output intensity of LED and HID sources in a useful way due to a number of factors, including:

  • The number of LEDs
  • The inherent radiation pattern of the devices (LEDs are unidirectional while HID lamps have an omnidirectional broad emission pattern)
  • The use of reflectors and lenses

The aim is to maximize the transfer of the emitted light from the light source to the plant leaves. Therefore, it may be more interesting to consider how light is delivered to the plants.

There is no perfect emission distribution pattern, but there are some that are more suitable for certain greenhouse configurations. Precision overhead luminaires and lenses can be used to control the emission pattern of HID devices and focus light to the plant growth areas. This is necessary in small greenhouses with widely separated cultivation areas.

Canopy photon capture efficiency of above 90% can be achieved in this manner, regardless of the light source. But capture rates near to 100% can be achieved using LED intracanopy lighting. The heat generated by HID fixtures makes intracanopy lighting infeasible.

Efficiency of LED vs. HID Lighting

The potential efficiency of LEDs over traditional lighting sources has long been recognized. This is because of their low losses, generated as heat, meaning a greater proportion of the electricity goes toward generating light. Additionally, this means the light source can be placed extremely close or even within the plant canopy.

The varying cost per photon flux means that LED efficiency is highly sensitive to electricity prices. As the price of electricity increases, the savings of implementing an LED lighting system become far more significant.

In our next post, we’ll discuss the three remaining properties that contribute to the advantages of LEDs over HID lighting: light quality, lifespan, and physical and environmental impact.

In the meantime, where can you find products to support LED lighting in horticultural applications? Right here, of course!

Wurth Electronics offers the WL-SMDC SMD Mono-color Ceramic LED Waterclear range of LEDs. The WL-SMDC range has been expanded to include wavelengths of 450 nm (Deep Blue), 660 nm (Hyper Red), and 730 nm (Far Red), which have been optimized to match the absorption spectra of photosynthetic pigments.

In addition to the existing products in the WL-SMDC, WL-SMTC, WL-SUMW, and WL-SIMW, a diverse range of combinations is possible that can be catered to the target cultivar. Please contact us if you would like to learn more!

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