1) Powerful light output
One of the advantages of HPS growth lights is its powerful light output. The powerful light output can provide plants with sufficient light energy required for photosynthesis, especially for tall plants or densely planted crops. The powerful light output of HPS is very effective when covering large planting areas, helping to promote plant growth, flowering, and fruit formation, increasing yield and quality.
2) Suitable for flowering and fruiting stages
The second advantage of HPS grow lights is that they perform well during the flowering and fruiting stages of plants because the visible light spectrum released by HPS is strong in the orange-yellow and red wavelength range, which is important for photosynthesis light during the flowering period and fruit ripening of plants, and has helped increase production and improve quality. In 2015, P. Paponov et al. published a study in "Plant Cell Reports" on the role of HPS lamps in the growth cycle of cannabis (marijuana plant). Research results show that using HPS lights during the flowering and fruiting stages can increase flower bud formation and yield of cannabis plants, thereby improving their growth performance.
3) Mature technology and reliability
One of the advantages of HPS grow lights is that the technology is very mature and reliable. The development of high-pressure sodium lamps (HPS) can be traced back to the 1920s when engineers began to study the luminescent properties of sodium. However, real commercial applications began in the 1960s. This kind of lamp has existed and been widely used for decades. The technology of HPS has been verified and improved over time, and its performance and reliability have become the first choice of many growers. One of the light sources, especially when a stable and reliable light source is required.
Therefore, HPS grow lights perform well in terms of light output, applicable stages, and technical reliability, making them one of the grow light options worth considering for growers.
3. Disadvantages of HPS grow lights
1）High energy consumption
First of all, the problem of high energy consumption of HPS grow lights is particularly prominent. High light output is undoubtedly an advantage of HPS. However, high light output will consume more electricity during use, which is a problem for growers when used on a large scale. Said that it means higher electricity expenses and higher operating costs. Compared with LED, it is not environmentally friendly and hurts the environment.
2） Generate a lot of heat
The working principle of HPS emits high temperatures and generates a large amount of heat during operation, and it converts thermal energy instead of electrical energy, so the energy efficiency is relatively low. Such a situation will significantly increase the temperature of the planting environment, especially in closed indoor planting systems and greenhouses. Excessive temperature will cause damage to the growth of plants. In severe cases, it will cause the leaves of the plants to be burned, so environmental control has high requirements, in order to balance the indoor growing temperature, additional cooling systems such as fans, air conditioners or ventilation systems need to be added. This will further add additional energy consumption and cost to the equipment.
3）Relatively short service life
Generally speaking, the service life of HPS lamps is between 10,000 and 20,000 hours, and the service life is relatively short. Because the light output of HPS lamps will gradually weaken and decrease during use, and the bulbs are not damaged, growers will need to replace the bulbs more frequently due to insufficient light intensity, resulting in production terminals or reduced production capacity, thus increasing maintenance costs and labor.
The advantages of HPS grow lights in terms of initial cost and high light output are unquestionable. However, their high energy consumption, high heat, and short service life have caused more and more growers to turn to longer service life and higher maintenance costs. Low-cost alternative light sources, such as LED grow lights.
Ⅱ. Learn about LED grow lights
2. Advantages of LED grow lights
1）High energy efficiency
LED grow lights are known for their efficient energy usage as they can convert more energy into light energy. LED lights use solid-state light-emitting technology. Compared with traditional fluorescent lamps or high-pressure sodium lamps, LED grow lights can provide the same or higher light output with less energy and generate almost no heat, which helps reduce greenhouse or indoor temperatures and the temperature of the growing environment, thereby reducing energy consumption and operating costs. More economical and affordable in large-scale planting and long-term operations.
2) Low heat generation
LED grow lights generate almost no additional heat. Because LEDs are semiconductor materials, LED lights only generate a small amount of heat when working. They are very helpful for indoor growing environments and do not require additional cooling equipment to maintain appropriate conditions. The temperature can reduce the heat accumulation around the plants and reduce the risk of heat stress to the plants.
3) Long service life
LED grow light is famous for its long service life. LED lamps can usually continue to work for more than 550,000 hours, and their service life is far longer than traditional fluorescent lamps or high-pressure sodium lamps. Growers can change bulbs less frequently. A one-time investment can bring long-term benefits, reducing maintenance costs and labor costs. Moreover, LED lighting solutions can provide more stable light output for plants, helping to improve planting efficiency and yield.
4）Adjustable spectrum
The spectrum adjustability of LED grow light is one of its unique advantages. LED grow light technology can simulate different natural lighting conditions by adjusting the color and spectrum of LEDs, such as sunlight, sunrise, and sunset spectrums to stimulate the growth of a plant‘s cycle. Because plants require different wavelengths of light during growth, flowering, and fruiting, growers can precisely adjust the spectrum according to the specific needs of different plants during their growth cycle, maximizing plant growth speed, shape, and yield.
In summary, LED grow lights have become one of the most popular grow light options in modern plant cultivation due to their high energy efficiency, low heat generation, long life, and adjustable spectrum.
3. Disadvantages of LED grow lights
1）Initial investment is high
One disadvantage of LED grow lights is the higher initial investment. LED technology is relatively new, and to ensure the performance and reliability of LED grow lights, it is often necessary to select high-quality components with relatively high cost of parts. On the other hand, high-end LED grow light products are also equipped with advanced spectrum adjustment and lamp control functions to meet the needs of different plant growth stages. This will be a huge burden for smaller growers and cause The overall operation to require higher purchasing input costs. However, the price of LED grow lights has gradually dropped over the years, resulting in lower overall cost investment for growers. Due to the long life and high energy efficiency of LEDs, LED grow lights are still a cost-effective and sustainable choice.
2）Technical complexity
The technical complexity of LED grow lights mainly stems from the complex electronic technology and optical principles involved in LED lights. Design an appropriate optical system to ensure that light can evenly cover the plant surface and provide appropriate light intensity and spectrum. Some high-end LED grow lights also have the functions of spectrum adjustment, energy saving, intelligent lighting adjustment, and remote monitoring and control. They require professional knowledge and skills to install, operate, and maintain correctly. And this also involves the issue of maintenance and repair costs. Because LED grow lights contain complex electronic and optical components, maintenance and repair require professional knowledge, so the repair maintenance costs may be higher.
In summary, although LED grow lights have many advantages, their disadvantages such as high initial investment and technical complexity also need to be seriously considered. Growers need to weigh these factors when choosing grow light and make a suitable choice based on their own planting needs, budget, and technical capabilities.
Ⅲ. HPS VS LED Grow Light—Performance Comparison
1. Energy consumption comparison
Considering energy consumption is a key factor when choosing to grow lights that are right for you. There are indeed differences in energy consumption between HPS (high-pressure sodium lamps) and LED (light-emitting diode) grow lights. Let’s compare them below:
HPS grow light energy consumption: HPS grow light requires relatively high electrical energy to produce sufficient light energy, and most of the electrical energy is converted into heat energy instead of light energy, so the energy consumption is relatively high, and long-term use will cause energy costs. Cumulatively, it has brought relatively large economic pressure to growers.
LED grow light energy consumption: LED grow lights have the advantages of lower energy consumption and more energy saving. The LED's semiconductor materials and advanced optical technology can convert more electrical energy into light energy instead of heat energy, maximizing the efficiency of converting electrical energy into light energy. From a long-term project investment perspective, LED lighting solutions with low energy consumption and high light energy will bring higher energy-saving and economic benefits to growers.
Let us give an example to illustrate this energy consumption comparison: When you invest in an indoor cannabis cultivation project, you need to provide 1000 watts of light intensity to the cannabis plants. When you choose HPS grow lights, you need to consume 1000 watts of electricity, while LED lights may only consume about 500 watts of electricity. It is obvious that if we compare with the same light intensity, LED grow lights can provide the same lighting effect with lower power, thereby reducing energy consumption.
In 2021, M. S. M. M. Bona et al. published a study in the journal "Plant Growth Regulation" comparing the energy consumption of HPS and LED lights in the indoor cultivation of cannabis. M. S. M. M. Bona et al. quantitatively analyzed the energy consumption of HPS and LED grow lights and examined their impact on the growth and yield of cannabis plants. Research results show that under the same growing environment, LED grow lights consume less energy than HPS grow lights, but have better light efficiency, which further confirms the energy efficiency advantage of LED lights in cannabis cultivation.
Therefore, taking into account the difference in energy consumption, LED grow lights have better advantages than HPS in terms of energy consumption. LED grow lights have lower energy efficiency, but more efficient light energy. If growers hope to reduce the energy cost of planting and improve planting efficiency, LED grow lights are a more energy-saving and affordable choice.
2. Light efficiency (light output efficiency) comparison
When choosing grow lights that suit you, light efficiency (light output efficiency) is a key factor. There are indeed differences in light efficiency (light output efficiency) between HPS (high-pressure sodium lamps) and LED (light-emitting diode) growth lamps. Let’s compare them below:
HPS grow light output: HPS grow lights are famous for their powerful light output, but when they work, they convert electrical energy into heat energy which is stronger than light energy, so the efficiency of light energy is relatively low. The PPF value of HPS lamps is generally between 1.0-1.4 µmol/J. This means that 1.0 to 1.4 micromoles of photons can be generated per watt of electricity consumed, which means that a large amount of electricity is required to achieve the desired light output, which will undoubtedly increase energy costs and the operating costs of additional cooling.
LED grow light output: The light output of a single LED element of an LED grow light will be lower than that of an HPS. However, an LED grow light is composed of hundreds or thousands of LED units through optical design, providing a similar or even higher and more stable total light output than HPS. The PPF value of high-quality LED lamps is usually between 2.0-3.5 µmol/J, and some high-end models can even reach more than 3.5 µmol/J. This high efficiency is mainly due to advanced LED technology, which can convert more electrical energy into effective light energy instead of converting it into heat energy like HPS. Less heat energy naturally reduces cooling requirements and reduces operating costs.
In 2020, Hawley et al. compared the light effects of HPS and LED lights in cannabis cultivation in a study published in the journal Frontiers in Plant Science. Research has found that LED lights are more efficient in energy use and can provide higher photosynthetically active radiation (PAR), thereby significantly improving cannabis growth and yield. Experimental results show that the light efficiency of LED lights is significantly higher than that of HPS lights, and LED lights can better meet the lighting needs of cannabis plants.
Therefore, in terms of energy efficiency, LED lights are significantly better than HPS lights, especially in terms of photosynthetic light quantum efficiency and light efficiency. Not only are LED lights more efficient at converting electrical energy into the light plants need, but they are also able to provide more light with less electricity consumption due to their high light efficiency.
3. Spectral quality comparison
Spectral quality is an important factor that growers pay more attention to when choosing grow lights. HPS (high-pressure sodium lamps) and LED (light-emitting diode) grow lights have their own advantages in terms of light efficiency (light output efficiency) and spectral quality. Let's compare them below:
High-pressure sodium lamp (HPS) spectral characteristics: We can look at the spectral diagram of the HPS growth lamp below. It can be seen that the spectral characteristics of the HPS growth lamp are mainly characterized by a sharp peak appearing in the red and yellow areas (560-600 nanometers), these wavelengths are very effective for plant growth during the flowering and fruiting stages. Although the advantage is that the spectrum is concentrated, it lacks blue light and other important spectral components. The spectral range is narrow and cannot fully meet the needs of plants at different growth stages. It is especially not ideal for the overall growth of the plant (such as leaf expansion and stem growth). 
Light-emitting diode (LED) spectral characteristics: One of the advantages of LED grow light is that it simulates natural sunlight, providing higher spectral efficiency and making photosynthesis more efficient. We can look at the picture. The spectrum of LED grow light includes blue light (440-470 nanometers), red light (630-660 nanometers), and part of far-red light (700-750 nanometers), and sometimes includes ultraviolet light and green light. This full-spectrum coverage not only meets the needs of plants at different growth stages, providing optimized light support from seedlings to flowering and fruiting but also maximizes plant growth efficiency and yield by adjusting the ratio of different wavelengths.
In 2020, S. Magagnini and his team published a study in the Journal of Applied Horticulture, exploring the effects of different spectra on the growth and metabolites of cannabis plants. Studies have shown that although HPS grow lights perform well in a specific spectrum, the spectrum is relatively single and concentrated in the red light region. The spectral quality is far inferior to LED grow light, resulting in lower photosynthesis efficiency of plants in the early growth stage. On the contrary, LED grow lights can better simulate natural sunlight and provide full spectrum coverage of blue light, red light, green light, and far-red light, meeting the needs of cannabis plants at different growth stages and improving growth efficiency and yield.
Therefore, in terms of spectral quality, Full Spectrum LED grow lights are undoubtedly a better choice and can better meet the needs of modern growers.
4. Service life comparison
Service life is an important factor for growers when choosing grow lights. There is a significant difference in service life between HPS (high-pressure sodium lamps) and LED (light-emitting diode) grow lights. Let’s compare them below:
High-pressure sodium lamp (HPS) service life: The service life of HPS growth lamps is usually between 10,000 and 20,000 hours because, in the middle and late stages of planting, the light output of HPS growth lamps will gradually weaken. To maintain continuous and stable light for plants, the effect requires more frequent replacement of light bulbs, usually once every 1-2 years, which undoubtedly increases the cost of replacement, as well as maintenance and labor costs at home.
Light-emitting diode (LED) service life: The service life of HPS grow lights is usually between 50,000 and 100,000 hours. LED grow lights can maintain high-efficiency light output for a long time with little need to replace the chip, and the light effect decays slowly. Many LED lamps can still maintain more than 70% of their initial light output at the end of their service life. It has the advantages of high light efficiency, low energy consumption, and low maintenance costs.
2020, S. B. Bliznyuk et al. research in the journal "Agricultural Science and Technology", S. B. Bliznyuk et al. published a study exploring the long-term performance of HPS and LED lights in cannabis cultivation. They found that the light output of LED lamps decayed slowly during use, while the light output of HPS lamps decreased significantly after being used for some time. Specific data shows that LED lamps still can maintain about 70% of their initial light output after 40,000 hours of use, while HPS lamps may drop below 50% of their light output after 20,000 hours of use.
Therefore, LED grow lights are significantly better than HPS grow lights. While HPS grow lights offer certain advantages in terms of initial light output, their short lifespan and high maintenance requirements make them more costly over the long term. Not only do LED lights have a longer lifespan, but maintenance requirements and costs are also significantly reduced. Therefore, in the long run, although the initial investment in LED lights is higher, their low maintenance costs and high economic benefits make them a more ideal choice.
5. Cost-benefit comparison
When comparing the cost-effectiveness of high-pressure sodium (HPS) and light-emitting diode (LED) grow lights, consider the initial investment, operating costs, maintenance expenses, and long-term benefits. The following is a detailed comparison:
Cost-effectiveness of high-pressure sodium lamps (HPS): The initial purchase cost of HPS grow lamp projects is relatively low, and the installation cost is relatively low. During use, an additional cooling system is required to digest the excess heat energy generated by HPS, because HPS uses much of the electrical energy and is converted into heat rather than effective light, which not only increases electricity bills but also requires additional cooling equipment to manage the heat. In terms of maintenance, the life of HPS bulbs is relatively short, and the bulbs need to be replaced regularly every 1-2 years, which increases additional operating costs. In addition, in the long run, the light efficiency of HPS gradually decreases. If the ideal light is to be achieved, output, growers need to replace equipment and maintain equipment more frequently.
Cost-Effectiveness of Light-Emitting Diodes (LEDs): A high-quality LED grow light typically costs between $300-$1,000, so the initial purchase cost of LED grow lights is relatively high. However, in terms of energy consumption, LED lamps not only have low energy consumption but also have high luminous efficiency. They usually only require lower wattage to provide the same or higher light output, which greatly reduces electricity bills. For example, a 600W LED fixture can replace a 1000W HPS fixture. In terms of maintenance costs, the lifespan of LED growth lights is as high as more than 5W hours, and there is a rare chance that the chip will break and need to be replaced. The heat dissipation system is good, there is no need to add additional cooling equipment, and the maintenance cost is relatively low. Therefore, although the purchase cost of LED is high in the long run, it consumes less energy and has low maintenance costs. More importantly, LED growth lights have high light efficiency and long life. For growers who pursue long-term economic benefits and higher efficiency, LED grow lights show higher economic benefits in long-term use.
2020, J. P. Mitchell et al. Study: In the journal Industrial Crops and Products, J. P. Mitchell et al. published a study evaluating the cost-effectiveness of HPS and LED lights in commercial cannabis cultivation. Research results show that although the initial investment of LED lights is higher, their efficient energy conversion and longer life make LED lights more cost-effective than HPS lights within a 3-5-year operating cycle. The study also pointed out that the spectral quality and uniformity of LED lights further improve the yield and quality of cannabis, thereby increasing economic benefits.
Although the initial cost of HPS grow lights is low, they have high energy consumption, short life, and high maintenance and operating costs, so they do not have an advantage. On the contrary, LED grow lights are significantly better than HPS grow lights. They have low energy consumption, high light efficiency, long life, and relatively low maintenance and operating costs. They are the best choice for long-term planting investment.
Ⅳ Advice on choosing the right grow light according to the needs of different growers
1. Which light is more suitable for beginners?
For beginners, LED lights are a very suitable choice. The attractive advantages of HPS grow lights are that their purchase costs are relatively low installation operations are relatively simple, and HPS light output is relatively strong, which is more effective for plant flowering and fruiting. However, HPS lamps generate a lot of heat, which requires the purchase of additional cooling equipment, high operating costs, and a short lifespan, which requires frequent replacement of bulbs. It is relatively complicated and costly for beginners.
On the contrary, although the initial cost of ED grow lights is relatively high, ED grow lights have higher energy efficiency and lower heat output. They do not require additional cooling equipment and the maintenance costs are relatively low. Therefore, in terms of long-term benefits, they are better than HPS. More suitable for beginners. Moreover, LED growth and other technologies are advanced in design, simple to install, have a long lifespan, and simulate the full spectrum of natural sunlight, which can provide different spectral needs of plants at different growth stages. For beginners who have made long-term investments, LED grow lights are undoubtedly the simplest and most economical lighting solution and a
2. Which light should commercial and large-scale growers choose?
When commercial growers plant on a large scale, choosing LED lights is a wiser decision. First of all, HPS grow lights are more popular in traditional commercial planting due to their powerful light output and low initial cost, because HPS grow lights play a key role in promoting the flowering and fruiting stages of plants. However, because its working principle is to convert electrical energy into heat energy rather than light energy, HPS growth lamps will incur additional cooling operating costs due to the disadvantages of high energy consumption and high heat, and the lifespan of HPS is relatively short, 1 -Lamps need to be replaced frequently between 2 years. It is a significant expense for large-scale growers.
In contrast, LED grow lights are an ideal lighting choice for commercial growers for large-scale cultivation because LED grow lights have significant advantages in terms of energy efficiency and long-term cost. LED grow lights are significantly more efficient at converting electrical energy into light energy than traditional HPS lights (high-pressure sodium lamps), which means LED lights can provide more light under the same power consumption. Moreover, the life of LED grow lights is longer, and the chip almost does not need to be replaced, which greatly reduces the frequency of replacement, maintenance costs, and production interruptions. Moreover, LED technology has become very advanced in modern times. High-quality LED grow lights also have the function of adjustable spectrum, which can provide the most suitable spectrum according to the different growth stages of different plants, improving yield and quality. Moreover, LED grow lights produce low heat and are more environmentally friendly. Therefore, for large-scale growers, LED grow light is undoubtedly a wiser choice, which can optimize the planting environment while reducing operating costs and achieving a higher return on investment.
3. Which light should I choose for my particular plant or particular growth stage needs?
When choosing a grow light for a particular growing need, the specific requirements of a particular plant species or growth stage need to be considered. First of all, HPS grow lights, with their powerful red and yellow light output, have significant effects in promoting the flowering and fruiting stages. Therefore, HPS lights are an effective choice for flowering plants that require a lot of light, such as tomatoes, peppers, etc. However, the spectrum of HPS lamps is relatively single and lacks blue light and other wavelengths, which may not meet the needs of some plants in early growth stages or that require specific spectral conditions. For example, seedling stage or leafy vegetables require more blue light to promote healthy leaf growth, and the effect of HPS grow lights may not be satisfactory at this time.
In contrast, LED grow lights are more flexible and efficient in responding to special planting needs. Modern full-spectrum LED grow lights can provide full spectrum coverage from blue light to red light, and can accurately adjust the proportion of light of different wavelengths to meet the needs of various plants at different growth stages. For example, in the seedling stage of plants, the proportion of blue light can be increased to promote the development of root systems and leaves; in the flowering and fruiting stages, the proportion of red light can be adjusted to promote the formation of flower buds and fruits. For plants that require specific spectral conditions, such as some flowers and herbs, the adjustability of LED grow lights makes them the best choice.
In addition, LED grow lights perform particularly well in certain growing environments, such as vertical farming and indoor growing systems. Its low heat output and high energy efficiency not only provide stable growing conditions but also reduce the need for cooling equipment, thereby lowering operating costs.
In summary, although HPS grow lights perform well in certain growth stages with high light requirements, their single spectrum and high heat output limit their application in special growing needs. On the contrary, LED grow lights, with their full-spectrum coverage and spectral adjustment capabilities, are better able to meet the needs of various special plants and growth stages. Therefore, for growers, especially those with special planting needs that require fine management of spectral conditions, LED grow lights are undoubtedly a more suitable choice.
