P. L. Light Systems Expert Article: What to Know When you are Transitioning from HPS to LED

Jillian Whitehead

Hybrid Lighting, LED luminaires, Return on Investment | April 27, 2021

Many growers are looking to switch from HID technology (HPS and MH luminaires) over to LEDs for reasons such as increased energy savings, reduced heat output, longer lifespan and greater spectral efficiencies.   And while LEDs can offer many advantages over HID luminaires, there are several things a grower should know before jumping in.   Since LEDs can cost 2-3 times more than HID luminaires, knowing how to manage costs and your crop growth are imperative to finding success with growing under LED luminaires. Below we have outlined 6 things to consider as you move from HID to LED technology.   

1. You may need to change up your growing environment.  While LEDs use up to 40% less energy than an HPS luminaire, you may need to make up some of that in increased heating costs during cold, dark months.  This is because LEDs do not emit heat in the same way HPS luminaires do, so growers who depend on the heat from HPS lamps to offset heating costs and/or for plant development, will need to compensate in the winter. The lack of radiant heat from LEDs can also affect your watering schedule and nutrient management.  In the case of watering, many growers require less water compared to growing under HPS lamps, however, this will depend on your particular application.  Nutrient uptake can also be affected, so monitoring your EC and performing regular scouting is essential to ensure your plants are growing healthy. 

Because LEDs do not emit radiant heat, you may need to make up for it with extra heating in the winter, depending on your climate

 2. You may need to add additional infrastructure such as wiring, and track or truss, to hang the LED luminaires, because there is currently no onetoone replacement of HPS to LED. In many cases, you may need 2-3 LEDs for every HPS luminaire, because of the way they distribute light over the crop. HID luminaires use reflectors to create a wide, diffused field of illumination over the crop. Since LED luminaires lack reflectors, they create a more directional, focused distribution of light, meaning you will need more luminaires to create the same uniformity over the crop. It is always recommended to have a professional lighting company create a customized light plan that will help show thbest coordinates to place the luminaires to get the highest uniformity.    


3. Consider a hybrid HID-LED application – this is a great solution for growers who want the benefits of both technologies.  A hybrid application allows you to take advantage of the diffuse light and radiant heating from the HPS luminaires during the winter months, while being able to turn on the LEDs in spring without having to heat up the greenhouse. This is perfect for vine crops, cannabis and ornamental production, which can rely on the radiant heat in the winter.  Another point to consider is that in a full LED transition, because of the directional distribution of light, you will likely need to install addition wiring and/or track to hang the lights. However, in a hybrid solution, you can help lower your capex costs by using existing infrastructure to hang the LEDs, allowing for a shorter payback period 

A hybrid installation allows the grower to take advantage of the diffuse light and radiant heating from the HPS luminaires during the winter months, while being able to turn on the LEDs in spring without having to heat up the greenhouse.

4. Be sure to take advantage of local rebate programs, which can help you save on upfront costs.  By installing a DLC listed luminaire, such as our HortiLED Top 2.0, you may be eligible to save on lighting equipment costs when buying new LEDs luminaires.  Growers should speak with their sales manager and/or energy provider to see what rebates they have available.   


5. Consider the design of the luminaire – LEDs can be built with either an external driver or an internal driver.  Having an integrated internal driver, like with the HortiLED Top 2.0, means you will have less shadowing on the canopy and therefore more light hitting your crop. And as we know, every 1% increase in light equals one percent increase in plant yield.  Having an internal driver also means you will have reduced installation and maintenance costs, which can affect your ROI.   

Having an integrated driver, like on the HortiLED Top 2.0, will help increase light and maintenance efficiencies


6. You will still need to perform some yearly maintenance.  An LED luminaire can last up to 50,000 hours, however, you still need to perform yearly maintenance and cleaning.  While LEDs boost a longer lifespan than HPS or MH lamps, they do need to be regularly maintained to keep them at their optimum and to ensure you are receiving the greatest amount of PAR light.  Just like with HID luminaires, dirt and dust can still build up on the LED lens, which can reduce the amount of light being emitted from your luminaire. To clean your LEDs, you simply need to wipe off any build up using a microfiber cloth and 1:100 vinegar-water solution (Do not use commercial cleaning products, soaps or detergents). For more information see our maintenance video here.  


An extra tip, is to set up a trial area in your grow space so you know what to expect when you go fully LED.  Once you know how your crop grows under LEDs, the better control you can have over areas such as yield, quality and growth.  To get started on your transition from HPS to LED contact one of our local sales managers.