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Light. This is one of the most important considerations for any grower. How the light is positioned, what light spectrum to use, the cost of the lights, the warmth of the lights, the technical implications of light design and colour on crop yield, and the type of lights used to achieve the best possible results. Light is an art, and it is one that has inspired debate, ignited discussion, and delivered innovation. 

Two of the most commonly used are LED grow lights and HPS grow lights. These have been around for a while, but there are some essential differences between the two. While HPS grow lights have been traditionally favoured by growers in the past, LED grow lights are increasingly taking centre stage thanks to their sustainability and long-term cost efficiency. LED grow lights offer immense value to the grower across multiple areas but both systems bring something unique to the grower. Here we take a look at LED vs. HPS grow lights and the differences between them. 

HPS Grow Lights: Unpacked 

High-Pressure Sodium (HPS) grow lights are a common feature in commercial grow spaces as they’ve been around for more than 75 years. These lights have been the most common choice for growers as they offer immense value in terms of cost to purchase, yield, and light spectrum. HPS grow lights use a pressurised quartz tube that’s filled with sodium, xenon and mercury. They release a beam of white light that sits in the yellows 570-590 (nm), oranges 590-630 (nm) and reds 630-750 (nm) colour spectrum, light that’s most important for photosynthetically active radiation (PAR). HPS grow lights use high-voltage energy to create light that’s as close to the intensity of natural sunlight as possible.  

LED Grow Lights: Unpacked 

Light-Emitting Diodes (LED) grow lights have become increasingly invaluable to commercial and non-commercial growers as they’re significantly less heavy on the energy usage than HPS grow lights and they usually have a longer life span. LED grow lights allow energy to move in different directions with minimal resistance using a p-n junction. This junction uses two materials that have different levels of electrons attached to them. When power moves through the junction, the extra electrons on one material are pulled across to the material with fewer electrons and this process creates the light that the LED grow lights emit. This light colour changes dependent on the materials used within the LED grow lights so they can be easily customised to suit different grow areas, requirements and crops. This is one of the biggest advantages offered by LED grow lights – they can be used to create bespoke lighting solutions that can fundamentally transform a grower’s crop and yield. 

LED vs HPS Grow Lights: The Heat Difference 

One of the biggest differences between LED grow lights and HPS grow lights is the heat they emit. HPS grow lights produce a lot of heat. Their design, materials and energy consumption make them a hot source of light so they need to be positioned at a careful distance from the crops to ensure that they don’t impact on yield or the health of the plants. This heat can potentially be useful in colder climates if growers want to continue growing plants throughout the colder seasons – HPS grow lights offer a nice heat balance that can be used in conjunction with LED grow lights to create the perfect grow conditions in variable climates. That said, HPS grow lights are not a good fit for smaller spaces or grow areas that are optimised to maximise the use of space as the heat they emit can be too overwhelming for the area.  

LED grow lights, on the other hand, are much cooler than HPS grow lights. Producing only tiny amounts of heat, LED grow lights can be placed closer to the plants and, because they provide different types of light spectrum, they can be positioned intelligently around a grow space to optimise plant health and yield. Working with companies that understand spectrum, light, and technology, growers can use LED grow lights in a variety of different ways, optimising their use of space and light in unexpected ways. LED grow lights can fit neatly into small, tight, and confined spaces as well as into large commercial spaces, making them a lot more flexible than HPS grow lights. However, LED grow lights may require additional temperature management solutions to ensure that the climate within the grow space remains consistent, especially in colder climates. 

LED vs HPS Grow Lights: The Energy Factor 

It’s almost impossible to talk about the energy usage differences between HPS grow lights and LED grow lights without also talking about the cost. LED grow lights are more expensive when it comes to their initial upfront purchasing price and this can often be seen as a limiting factor for growers. However, LED grow lights deliver a measurable return on this initial investment because they are more cost-effective to run and far more energy efficient. 

While HPS grow lights are significantly more energy efficient and cost-effective than other forms of lighting such as metal halide grow lights, incandescent grow lights or fluorescent grow lights, they are still hungry for power. HPS grow lights convert only 30% of the energy they use into usable light while LED grow lights convert about 50% of electricity into light. This is where LED grow lights really do shine. Research that unpacked the use of LEDs across different climates and applications found that LED grow lights can potentially save 10-25% of total greenhouse energy demand. These lights are also far better for the environment in the long term as they can be managed and disposed of safely compared to HPS grow lights.  

LED vs. HPS Grow Lights: The Cost Factor 

Everyone is worried about cost. It makes sense – optimised yields, grow spaces and lighting systems are all about getting more for less. This is, as mentioned earlier, a factor that does give some growers pause when considering investment into LED grow lights. They are more expensive to set up initially, and this cost cannot be bypassed if you want a solution that delivers the right results. That said, LED grow lights do consume less power, deliver better long-term value and cost less to maintain than HPS grow lights. They also last for longer.  

The longevity of LED grow lights makes them a sustainable and strategic move. There may be a higher upfront cost, but over the long-term LED grow lights deliver better value for money and return on investment. LED lighting system manufacturers found that the average LED grow light lifespan – variable dependent on location, use case and other factors – was around 50,000-70,000 hours while HPS grow lights were only expected to last for up to 20, 000 hours 

LED vs HPS Grow Lights: The value adds 

LED lighting offers growers a more customisable and capable lighting solution than HPS grow lights for three very simple reasons: 

  • The grower can control heat and light more effectively 
  • The costs can be measurably managed and reduced over the long term 
  • They can be customised into bespoke solutions that perfectly match the needs of the farmer, crop type, climate and available grow space

The fact that LED grow lights are less stressful on the budget and the plant makes them a solid investment for the grower and, with the right partner, a bespoke LED grow light implementation can deliver precise results that can be constantly managed to ensure optimised results.  

The differences between LED grow lights vs. HPS grow lights are interesting, not least because there remains plenty of debate around the real value of each and whether or not they really deliver what they promise. Ultimately, the real value comes down to the results and while both lighting systems have shown their mettle over the years, LED grow lights are measurably more cost-effective, sustainable, efficient and capable. Below is a checklist that covers all the differences between LED grow lights and HPS grow lights: 

  • LED grow lights come in multiple light spectrums so can be customised to suit crop, space and yield very effectively while HPS grow lights are in the yellows 570-590 (nm), oranges 590-630 (nm) and reds 630-750 (nm) colour spectrum. 
  • HPS grow lights are energy hungry and therefore cost more to run and maintain compared to the energy efficiency of LED grow lights. 
  • LED grow lights have a longer lifespan than HPS grow lights and are more environmentally safe to dispose of. HPS grow lights break more easily and have to be disposed of using a specialised recycling partner.  
  • HPS grow lights emit more heat than LED grow lights which means that they are well suited to colder climates and that LED grow lights will need temperature support to ensure a stable grow climate. 
  • To get the most value for your LED grow light installation it’s advisable to work with a qualified company that can provide a bespoke service. LED grow lights require careful positioning to ensure the right light spectrum and overall lighting efficiency while HPS grow lights have a wider beam so they are more forgiving. That said, LED grow lights ultimately deliver more value as a result.   

Work with a trusted partner who can create the right recipe for your environment and who has the latest technology and science at their fingertips, ready to help you shift your yield forwards. LED grow lighting can see you achieve returns on investment that help you grow more for less and achieve more over the long term. We can help you transform your greenhouse lighting with the right technology, expertise and science. Contact us on 01332 410601 to speak to one of the team.