The types of facilities in facility horticulture mainly include plastic greenhouses, sunlight greenhouses, multi story greenhouses, and plant factories. Due to the fact that facility buildings block natural light sources to a certain extent, indoor lighting is insufficient, resulting in reduced crop yield and quality. Therefore, fill lights play an indispensable role in the high-quality and high-yield of facility crops, but also become the main factor in increasing energy consumption and operating costs within the facility. For a long time, artificial light sources used in the field of facility horticulture mainly include high-pressure sodium lamps, fluorescent lamps, metal halide lamps, incandescent lamps, etc. The prominent disadvantages are high heat production, high energy consumption, and high operating costs. The development of the new generation of Light Emitting Diodes (LEDs) has made it possible to apply low energy artificial light sources in the field of facility horticulture. LED has advantages such as high photoelectric conversion efficiency, use of direct current, small size, long lifespan, low energy consumption, fixed wavelength, low thermal radiation, and environmental protection. Compared with commonly used high-pressure sodium lamps and fluorescent lamps, LED not only allows for precise adjustment of light quantity and quality (such as the proportion of light in various bands) according to the needs of plant growth, but also allows for close illumination of plants due to its cold light properties, thereby increasing the number of cultivation layers and space utilization, achieving energy-saving, environmental protection, and efficient space utilization functions that traditional light sources cannot replace. Based on these advantages, LED has been successfully applied in facility horticultural lighting, basic research on controllable environments, plant tissue culture, factory seedling cultivation, and aerospace ecosystems. In recent years, the performance of LED grow lights has been continuously improving, their prices have gradually decreased, and various specific wavelength products have been gradually developed. Their application scope in agriculture and biology will be even broader. This article reviews the current research status of LED in the field of facility horticulture, with a focus on the photobiological basis of LED supplementary lighting applications, the impact of LED supplementary lighting on plant photomorphogenesis, nutritional quality and anti-aging, the construction and application of light formulas, and other aspects. It also analyzes and looks forward to the current problems and prospects of LED supplementary lighting technology. The effect of LED supplementary light on the growth of horticultural crops The regulatory effects of light on plant growth and development include seed germination, stem elongation, leaf and root development, phototropism, chlorophyll synthesis and decomposition, and flower induction. The lighting environment elements inside the facility include light intensity, light cycle, and spectral distribution. By manually supplementing light, their elements can be adjusted without being limited by weather conditions. Plants have the characteristic of selective absorption of light, and different light receptors perceive light signals. Currently, it has been found that there are at least three types of light receptors in plants: photosensitizers (absorbing red and far red light), cryptocyanins (absorbing blue and near ultraviolet light), and ultraviolet light receptors (UV-A and UV-B). Using a specific wavelength light source to illuminate crops can improve the photosynthetic efficiency of plants, accelerate their light morphogenesis, and promote their growth and development. Plant photosynthesis mainly utilizes red orange light (610-720 nm) and blue purple light (400-510 nm). By utilizing LED technology, monochromatic light (such as red light with a peak of 660nm and blue light with a peak of 450nm) that conforms to the strongest absorption band of chlorophyll can be emitted, with a spectral domain width of only ± 20 nm. At present, it is believed that red orange light can significantly accelerate plant development, promote the accumulation of dry matter, form bulbs, tubers, leaf bulbs, and other plant organs, cause plants to bloom and bear fruit earlier, and play a dominant role in plant coloration; Blue and purple light can control the phototropism of plant leaves, promote stomatal opening and chloroplast movement, inhibit stem elongation, prevent plant overgrowth, delay plant flowering, and promote the growth of nutrient organs; The combination of red and blue LED can compensate for the deficiency of monochromatic light in both, forming a spectral absorption peak that is basically consistent with crop photosynthesis and morphology. The light energy utilization rate can reach 80%~90%, and the energy-saving effect is significant. Equipping LED supplementary lights in facility horticulture can achieve significant yield increase effects. Studies have shown that 300 μ The number of fruits, total yield, and single fruit weight of cherry tomatoes under 12 hours (8:00-20:00) of supplementary lighting with mol/(m? · s) LED strips and LED tubes were significantly increased. The supplementary lighting with LED strips increased by 42.67%, 66.89%, and 16.97%, respectively, while the supplementary lighting with LED tubes increased by 48.91%, 94.86%, and 30.86%, respectively. Full growth period LED light replenishment [red blue light quality ratio of 3:2, light intensity of 300] μ The treatment of mol/(m? · s) significantly increased the single fruit weight and unit area yield of Jiegua and eggplant, with Jiegua increasing by 5.3% and 15.6%, and eggplant increasing by 7.6% and 7.8%. By adjusting the temporal and spatial distribution of LED light quality, intensity, and duration throughout the entire growth period, it is possible to shorten the plant growth cycle, improve the commercial yield, nutritional quality, and morphological value of agricultural products, and achieve efficient, energy-saving, and intelligent production of horticultural crops in facilities. Application of LED supplementary light in vegetable seedling cultivation LED light source regulation of plant morphogenesis and growth and development is an important technology in the field of greenhouse cultivation. Higher plants can sense and receive light signals through photoreceptor systems such as photosensitive pigments, cryptocyanins, and phototropins, and regulate morphological changes in plant tissues and organs through intracellular messenger transduction. Photomorphogenesis is the process in which plants rely on light to control cell differentiation, structural and functional changes, as well as tissue and organ development. This includes effects on partial seed germination, promotion of apical dominance to inhibit lateral bud growth, stem elongation, and induction of meridional movement. Vegetable seedling cultivation is an important part of facility agriculture. Continuous cloudy and rainy weather can lead to insufficient lighting in the facilities, making seedlings prone to elongation, which in turn affects the growth, flower bud differentiation, and fruit development of vegetables, ultimately affecting their yield and quality. In production, some plant growth regulators such as gibberellin, auxin, paclobutrazol, and chloramphenicol are used to regulate the growth of seedlings. However, the unreasonable use of plant growth regulators can easily pollute vegetables and facility environments, which is detrimental to human health. LED supplementary lighting has many unique advantages in supplementary lighting, and the application of LED supplementary lighting in seedling cultivation is a feasible approach. In low light [0-35] μ LED replenishment under the condition of mol/(m? · s) [25 ± 5] μ In the mol/(m? · s) experiment, it was found that green light promoted the elongation and growth of cucumber seedlings, while red and blue light inhibited seedling elongation. Compared with natural weak light, the strong seedling index of seedlings supplemented with red and blue light increased by 151.26% and 237.98%, respectively. Moreover, compared with monochromatic light, the strong seedling index of cucumber seedlings treated with composite light containing red and blue components increased by 304.46%. Supplementing cucumber seedlings with red light can increase their true leaf number, leaf area, plant height, stem thickness, dry and fresh weight, seedling strength index, root vitality, SOD activity, and soluble protein content. Supplementing with UV-B can increase the chlorophyll a, chlorophyll b, and carotenoid content in cucumber seedling leaves; Compared with natural light, supplementing LED red and blue light significantly increased the leaf area, dry matter quality, and seedling strength index of tomato seedlings. Supplementing LED red and green light significantly increased the height and stem thickness of tomato seedlings; LED green light supplementation treatment can significantly increase the biomass of cucumber and tomato seedlings, and the fresh and dry weight of young seedlings show an increasing trend with the increase of green light supplementation intensity. However, the stem diameter and strong seedling index of tomato seedlings increase with the increase of green light supplementation intensity; The combination of LED red and blue light can increase the stem thickness, leaf area, whole plant dry weight, root to shoot ratio, and seedling strength index of eggplants; Compared with white light, LED red light can increase the biomass of cabbage seedlings, promote the elongation growth and leaf expansion of cabbage seedlings; LED blue light promotes the thickening growth, dry matter accumulation, and seedling strength index of cabbage seedlings, leading to dwarfing of cabbage seedlings. The above results indicate that vegetable seedlings cultivated by combining light regulation technology have significant advantages. The influence of LED supplementary light on the nutritional quality of fruits and vegetables The protein, sugars, organic acids, and vitamins contained in fruits and vegetables are beneficial nutrients for human health. Light quality can affect the content of VC in plants by regulating the activity of VC synthesis and decomposition enzymes, and has a regulatory effect on protein metabolism and carbohydrate accumulation in horticultural plants. Red light promotes carbohydrate accumulation, while blue light treatment is beneficial for protein formation. The combination of red and blue light significantly improves the nutritional quality of plants compared to monochromatic light. Supplementing LED red or blue light can reduce the nitrate content in lettuce, supplementing blue or green light can promote the accumulation of soluble sugars in lettuce, and supplementing infrared light is beneficial for the accumulation of VC in lettuce. Supplementing with blue light can promote the increase of VC content and soluble protein content in tomatoes; The combination of red light and red blue light treatment promotes the sugar and acid content in tomato fruits, and the sugar to acid ratio is highest under the combination of red and blue light treatment; The combination of red and blue light can promote the increase of VC content in cucumber fruits. The phenolic substances, flavonoids, anthocyanins and other substances contained in fruits and vegetables not only have a significant impact on the color, flavor, and commercial value of fruits and vegetables, but also have natural antioxidant activity, which can effectively inhibit or eliminate free radicals in the human body. The use of LED blue light supplementation can significantly increase the content of anthocyanins in eggplant peel by 73.6%, while the use of LED red light and red blue combination light can increase the content of flavonoids and total phenols; Blue light can promote the accumulation of lycopene, flavonoids, and anthocyanins in tomato fruits. The combination of red and blue light can promote the generation of anthocyanins to a certain extent, but inhibit the synthesis of flavonoids; Compared with white light treatment, red light treatment can significantly increase the anthocyanin content in lettuce aboveground parts, but blue light treatment has the lowest anthocyanin content in lettuce aboveground parts; The total phenolic content of green leaf, purple leaf, and red leaf lettuce was higher under white light, red blue combined light, and blue light treatments, but it was the lowest under red light treatment; Supplementing LED ultraviolet or orange light can increase the content of phenolic compounds in lettuce leaves, while supplementing green light can increase the content of anthocyanins. Therefore, using LED supplementary lighting is an effective way to regulate the nutritional quality of fruits and vegetables in facilities. The effect of LED fill light on delaying plant aging The degradation of chlorophyll, rapid loss of protein, and RNA hydrolysis during plant aging are mainly manifested as leaf aging. Chloroplasts are highly sensitive to changes in the external light environment, especially significantly influenced by light quality. Red light, blue light, and a combination of red and blue light are beneficial for the morphogenesis of chloroplasts. Blue light is beneficial for the accumulation of starch granules in chloroplasts, while red and far red light have negative effects on chloroplast development. Blue light and the combination of red and blue light can promote the synthesis of chlorophyll in cucumber seedling leaves, while the combination of red and blue light can also delay the decline of chlorophyll content in the later stage. This effect becomes more pronounced with the decrease of red light ratio and the increase of blue light ratio. The chlorophyll content of cucumber seedling leaves under LED red and blue combined light treatment was significantly higher than that under fluorescent light control and monochromatic red and blue light treatment; LED blue light can significantly increase the chlorophyll a/b values of Wutai vegetable and green garlic seedlings. Changes in content of cytokinin (CTK), auxin (IAA), abscisic acid (ABA), and various enzyme activities occur during leaf senescence. The content of plant hormones is easily influenced by the light environment, and different light qualities have different regulatory effects on plant hormones. The initial steps of the light signal transduction pathway involve cytokinins. CTK promotes leaf cell expansion, enhances leaf photosynthesis, and inhibits the activities of ribonuclease, deoxyribonuclease, and protease, delaying the degradation of nucleic acid, protein, and chlorophyll, thus significantly delaying leaf aging. There is an interaction between light and CTK mediated developmental regulation, where light can stimulate an increase in endogenous cytokinin levels. When plant tissues are in an aging state, their endogenous cytokinin content decreases. IAA is mainly concentrated in areas with vigorous growth, and its content is minimal in aging tissues or organs. Purple light can enhance the activity of indole-3-acetic acid oxidase, while low levels of IAA can inhibit plant elongation and growth. ABA is mainly formed in aging leaf tissue, mature fruits, seeds, stems, roots and other parts. Under red blue combined light, the ABA content in cucumber and cabbage is lower than that under white and blue light. Peroxidase (POD), superoxide dismutase (SOD), ascorbic acid peroxidase (APX), and catalase (CAT) are important and light related protective enzymes in plants. If plants age, the activity of these enzymes will rapidly decrease. The effect of different light qualities on plant antioxidant enzyme activity is significant. After 9 days of red light treatment, the APX activity of rapeseed seedlings significantly increases, while the POD activity decreases; After 15 days of red and blue light irradiation, the POD activity of tomatoes was 20.9% and 11.7% higher than that of white light, respectively. After 20 days of green light treatment, the POD activity was the lowest, only 55.4% of that of white light; Supplementing with 4 hours of blue light can significantly increase the soluble protein content, POD, SOD, APX, and CAT enzyme activity in cucumber seedling leaves. In addition, the activities of SOD and APX gradually decrease with the prolongation of light exposure time. The activities of SOD and APX under blue and red light irradiation decreased slowly but remained higher than those under white light. Red light irradiation significantly reduced the peroxidase and IAA peroxidase activities in tomato leaves and eggplant leaves, but caused a significant increase in the peroxidase activity in eggplant leaves. Therefore, adopting a reasonable LED lighting strategy can effectively delay the aging of horticultural crops in facilities, improve yield and quality. Construction and application of LED light formula The growth and development of plants are significantly influenced by light quality and its different composition ratios. The light formula mainly includes several elements such as light quality ratio, light intensity, and light duration. Due to the differences in light requirements among different plants and their varying growth and development stages, it is necessary to optimize the combination of light quality, intensity, and replenishment time for the cultivated crops. Light quality ratio Compared with white light and single red and blue light, the combination of LED red and blue light shows a comprehensive advantage in the growth and development of cucumber and cabbage seedlings. When the ratio of red and blue light is 8:2, the stem diameter, plant height, plant trunk, fresh weight, and seedling strength index of the plant are significantly improved, while also promoting the formation of chloroplast matrix and basal grain layer and the output of assimilates. Under the red blue light ratio of 8:1, cucumber seedlings had the highest plant height, stem diameter, leaf area, seedling strength index, aboveground and whole plant fresh weight, and the seedling leaves had high POD and APX activities; Under the red blue light ratio of 6:3, the root activity, soluble protein and sugar content, and net photosynthetic rate of cucumber seedlings were the highest, and SOD activity was relatively high. The use of a combination of red, green, and blue light is beneficial for the accumulation of dry matter in red bean sprouts. Adding green light has a promoting effect on the accumulation of dry matter in red bean sprouts, with the most significant increase observed in the red green and blue light ratio of 6:2:1; The red and blue light ratio of 8:1 had the best effect on the elongation of the hypocotyl of red bean sprouts. The red and blue light ratio of 6:3 had a significant inhibitory effect on the elongation of the hypocotyl of red bean sprouts, but the soluble protein content was the highest. When using a red and blue light ratio of 8:1 for the treatment of luffa seedlings, the strongest seedling index and highest soluble sugar content were observed. When using a red and blue light ratio of 6:3, the highest chlorophyll a content, chlorophyll a/b ratio, and soluble protein content were observed in luffa seedlings. When using a red blue light ratio of 3:1 for celery, it can effectively promote the increase of celery plant height, petiole length, number of leaves, dry matter quality, VC content, soluble protein content, and soluble sugar content; In tomato cultivation, increasing the proportion of LED blue light promotes the formation of lycopene, free amino acids, and flavonoids, while increasing the proportion of red light promotes the formation of titratable acids; When using a red blue light ratio of 8:1 on lettuce leaves, it is beneficial for the accumulation of carotenoids, effectively reducing their nitrate content and increasing their VC content. Light intensity Plants are more susceptible to light inhibition when growing under weak light than under strong light. The net photosynthetic rate of tomato seedlings varies with light intensity [50, 150, 200, 300, 450, 550] μ The increase in mol/(m? · s) shows a trend of first increasing and then decreasing, and reaches 300 μ Reached maximum at mol/(m? · s); The plant height, leaf area, water content, and VC content of lettuce are within 150 μ Significant increase in mol/(m? · s) light intensity treatment at 200 μ Under the treatment of mol/(m? · s) light intensity, the fresh weight, total weight, and free aromatic acid content of lettuce aboveground parts were significantly increased, while at 300 μ Under the treatment of mol/(m? · s) light intensity, the leaf area, water content, chlorophyll a, chlorophyll a+b, and carotenoids of lettuce all decreased; Compared to darkness, with the increase of LED supplementary light intensity [3, 9, 15 μ The increase of mol/(m? · s) significantly increased the content of chlorophyll a, chlorophyll b, and chlorophyll a+b in black bean sprouts and vegetables, with a light intensity of 3 μ At mol/(m? · s), the VC content is highest at 9 μ The content of soluble protein, soluble sugar, and sucrose is highest at mol/(m? · s); Under the same temperature conditions, with the increase of light intensity [(2-2.5) lx x x 103 lx, (4-4.5) lx x x 103 lx, (6-6.5) lx x 103 lx], the seedling growth time of chili seedlings is shortened, and the soluble sugar content increases, but the chlorophyll a and carotenoid content gradually decreases. Illumination time Extending the light exposure time appropriately can alleviate the weak light stress caused by insufficient light intensity to a certain extent, help accumulate photosynthetic products in horticultural crops, and achieve the effect of increasing yield and improving quality. The VC content of sprouted vegetables shows a gradually increasing trend with the extension of light time (0, 4, 8, 12, 16, 20 hours/day), while the content of free amino acids, SOD, and CAT activity all show a decreasing trend; With the extension of lighting time (12, 15, 18 hours), the fresh weight of cabbage plants shows a significant increase trend; The VC content in the leaves and stems of Chinese cabbage was highest at 15 and 12 hours, respectively; The soluble protein content in the leaves of Chinese cabbage gradually decreased, but the highest was observed in the stems after 15 hours of treatment; The soluble sugar content in the leaves of cauliflower gradually increases, while the highest content is observed in the stems after 12 hours. In the case of a red and blue light ratio of 1:2, compared with a 12 hour light time, the 20 hour light treatment reduced the relative content of total phenols and flavonoids in green lettuce. However, in the case of a red and blue light ratio of 2:1, the 20 hour light treatment significantly increased the relative content of total phenols and flavonoids in green lettuce. From the above, it can be seen that different light formulas have different effects on the photosynthesis, light morphogenesis, and carbon and nitrogen metabolism of different crop types. How to obtain the optimal light formula, light source configuration, and formulate intelligent control strategies needs to take plant species as the starting point, and appropriate adjustments should be made according to the demand for horticultural crops, production goals, production factor conditions, etc., to achieve intelligent control of light environment under energy-saving conditions and the goal of high-quality and high-yield horticultural crops. Existing problems and prospects The significant advantage of LED fill lights is their ability to intelligently combine and adjust spectra based on the photosynthetic characteristics, morphological construction, quality, and yield requirements of different plants. Different types of crops and different growth stages of the same crop have different requirements for light quality, light intensity, and light cycle. This requires further development and improvement of light formula research, forming a huge light formula database, and combining with the research and development of professional lighting fixtures, in order to achieve the maximum value of LED fill lights in agricultural applications, thereby better saving energy consumption, improving production efficiency and economic benefits. The application of LED fill lights in facility horticulture has shown strong vitality, but the price of LED fill lights is relatively high, and the one-time investment is large. The fill light requirements for various crops under different environmental conditions are not clear, and the fill light spectrum, intensity, and fill light time are not reasonable, which inevitably leads to various problems when using fill lights. However, with the advancement and improvement of technology, the production cost of LED fill lights has decreased, and LED fill lights will be more widely used in facility horticulture. At the same time, the development and progress of LED supplementary lighting technology system combined with new energy will enable the rapid development of factory agriculture, household agriculture, urban agriculture, and space agriculture to meet the needs of people for horticultural crops in special environments.

The structure of LED street lights

The structure of LED street lights is not complicated, and after splitting it, there are several components as follows: LED light source (1W-200W), aluminum alloy heat dissipation aluminum sheet, LED constant current source (power supply), and lamp housing. In addition, street lights need to have sufficient height to illuminate a wider range, so necessary lamp posts are also necessary. Of course, in order to better shelter from wind and rain, lamp caps are also needed.

The commonly used LED lighting chips now include a single 1 W high-power white LED array and a high-power integrated packaged light source module Langzhong. The main parameters for measuring its advantages and disadvantages include: average road brightness, total illuminance uniformity, longitudinal illuminance uniformity, environmental ratio, glare control, etc.

The LED driver power supply is a key component of LED street lights and a bottleneck factor that affects the effectiveness and lifespan of LED street lights. Especially the issue of matching the lifespan of the driver power supply with the lifespan of the LED. At present, the light source of high-power LED street lights adopts low-voltage DC power supply, and a high-efficiency white light diode composed of GaN based power type blue light LED and yellow fluorescent powder. It has unique advantages such as high efficiency, safety, energy saving, environmental protection, long service life, fast response speed, and high color rendering index. The outer cover can be made of PC tubes, which can withstand high temperatures up to 135 degrees and low temperatures up to -45 degrees.

LED street light classification

LED street lights can be broadly divided into two types in terms of technology: vertical and integrated, depending on the arrangement of the lamp beads. Generally, using a single light source of over 10000 watts to manufacture street lights is classified. This is a type of LED street light that started to be used relatively early and now has relatively mature technology. Split type technology was used earlier and is now widely used by many enterprises.

The technology of using integrated chips as light sources to manufacture street lights is called integrated technology. Integrated technology is a relatively new technology for LED, which is currently flourishing because it has a larger luminous amount per unit area than discrete chips, and its market prospects are greater than discrete chips.

However, no matter what form it takes, it faces complex heat dissipation and lighting problems. It is necessary to scientifically solve these problems in order to improve light efficiency, achieve the advantages of energy conservation, environmental protection, and long lifespan of LED street lights, and truly establish the image of LED street lights as energy-saving, cost-effective, environmentally friendly, and high-end.

The advantages of LED street lights

1. LEDs do not contain harmful metal mercury, unlike high-pressure sodium lamps or metal halide lamps that pose a threat to the environment when discarded.

2. Compared to traditional street lights, LED street lights have extremely low maintenance costs, and high-power LED street lights have significant energy-saving effects. Replacing high-pressure sodium lights can save more than 60% of electricity. Based on these characteristics, LED street lights are gradually coming into people's sight.

3. In terms of light efficiency, high-pressure sodium lamps can reach up to 140 lm/W, which is higher than the current commercial high-power LED light efficiency of 100 lm/W. However, the color rendering index of LED is much higher than that of high-pressure sodium lamps. Moreover, under the same illumination, white LED is more helpful for drivers or pedestrians to recognize targets, and its road lighting effect and comfort are much higher than high-pressure sodium lamps.

4. The unique secondary optical design illuminates the LED street lights to the desired lighting area, further improving lighting efficiency and achieving energy-saving goals.

5. LED street lights have automatic control energy-saving devices, which can achieve maximum power reduction and save electricity while meeting lighting requirements at different time periods.

6. Easy to install, without the need for buried cables or rectifiers, simply connect the street lamp holder to the lamp post or nest the light source into the original lamp housing.

Disadvantages of LED street lights

1. The penetration ability is lacking, for example, on rainy or foggy days, the light of this type of lamp will be diluted, making it difficult to see clearly.

2. The design of LED street lights determines that their illuminance will be insufficient. Existing technology is not easy to achieve both energy-saving effects and improved illuminance. Therefore, sometimes the former cannot be fully achieved, and only minor adjustments can be made to the latter.

3. Excessive internal heat can easily cause damage. As it is used outdoors, sealing is chosen to protect the interior to prevent the influence of weather. As a result, the internal temperature will reach a high level after working for a period of time. If heat dissipation is not done well, it is easy to cause damage.

4. This type of lamp is usually easy to attract mosquitoes and insects, so it can affect the environment on main roads, and it is not suitable to be too close to residents.

5. Due to defects in the manufacturing process of white LED street lights and matching errors with reflective cups or lenses, it is easy to cause the problem of "yellow circles".

Key points for selecting LED street lights

1. Luminescence efficiency

Nowadays, LED lighting products are changing rapidly, among which high-power LED light sources (usually one watt per unit) have the most mature technology, and the bead light flux of conventional LED lights has exceeded 130LM/W. Next is to choose COB integrated LED light sources, whose luminous flux is steadily increasing with the advancement of technology. Generally, the higher the luminous flux, the higher the luminous efficiency and energy-saving effect, which is the most important indicator when purchasing LED street lights.

2. Light attenuation

Some unscrupulous merchants, in order to reduce costs, choose some LED beads with poor quality and severe light attenuation. Their lifespan of light attenuation to 80% is only 1000 hours, and they cannot be used as LED street lights that require long-term lighting.

3. Structure

LED street lights, due to their outdoor suspension, can withstand wind, frost, rain, and snow for a long time. The structure of the LED lamp head and its ability to withstand wind and rain as well as heat dissipation must be high.

4. Heat dissipation

The key component of LED street lights is the LED chip. As a semiconductor component, temperature has a significant impact. If the temperature is too high, it will seriously affect the service life of LED street lights. Some unreasonable heat dissipation designs can reduce the service life of street lights by half or even more.

5. Color rendering index

The color rendering index should generally be above 65 to ensure good color rendering and a more realistic presentation of the actual color.

Precautions for using LED street lights

1. The power supply must have a constant current

The lighting material characteristics of LED street lights determine their environmental impact, such as an increase in temperature and voltage, which will cause the current of the LED to increase accordingly. If operated for a long time beyond the rated current, it will greatly shorten the service life of LED beads.

2. Constant current accuracy of power supply

The constant current accuracy of some power sources in the market is poor, and the error may reach ± 8%. The constant current error is too large. A general requirement of ± 3% is sufficient. According to a 3% design plan. The production power supply needs to be fine tuned to achieve a ± 3% error.

3. The working voltage of the power supply

The recommended working voltage for general LEDs is 3.0-3.5V. After testing, most LEDs operate at 3.2V, so the calculation formula for 3.2V is more reasonable. The total voltage of N lamp beads in series=3.2 * N

4. The working current of the power supply

For example, the rated working current of LED is 350 milliampere. Some factories have used it all at the beginning and designed it to be 350 milliampere. However, in reality, the heat generated during operation at this current is very serious. After multiple comparative experiments, the design of 320 milliamperes is relatively ideal. Try to minimize heat generation and convert more electrical energy into visible light energy.

5. Series parallel connection and wide voltage of power boards

To ensure that the LED street light power supply operates within a wide input voltage range of AC85-265V, the LED series parallel connection method of the light board is important. Try not to use wide voltage and classify AC220V and AC110V as much as possible to ensure power supply reliability.

In addition, the number of series connections shall not exceed 45. Do not have too many parallel connections, otherwise the working current will be too high and the power supply will heat up severely.

6. Isolation/Non Isolation

Generally, if a 15W isolated power supply is made and placed inside the LED street light power supply tube, its transformer volume is large and difficult to fit inside. It mainly depends on the specific situation of the spatial structure, and the isolation can generally only reach 15W, with very few exceeding 15W, and the price is very expensive. So, the cost-effectiveness of isolation is not high. In fact, if non isolated safety measures are in place, there is no problem.

7. Power efficiency

The parameter of subtracting the output power from the input power is particularly important. The larger the value, the lower the efficiency, which means that a large part of the input power is converted into heat and dissipated; If installed inside the lamp, it will generate a very high temperature, combined with the heat emitted by our LED's light efficiency ratio, it will superimpose to produce a higher temperature. 9. Heat dissipation

The main factor in the heat dissipation scheme is that LED street lamp beads can greatly extend their lifespan when used under non overheated conditions, and aluminum alloy is generally used for easier heat dissipation. That is to say, the LED street light power supply beads are attached to the aluminum substrate, and the external heat dissipation area is maximized as much as possible.

Introduction to LED Grow Light LED Grow Light is an artificial light source that uses LED (Light Emitting Diode) as the light source to meet the lighting conditions required for plant photosynthesis. Classified by type, it belongs to the third generation of plant supplementary lighting fixtures! In environments lacking sunlight, this type of lighting fixture can act as sunlight, allowing plants to grow and develop normally or better. This type of lighting fixture has the function of strengthening roots, promoting, adjusting flowering period and color, promoting fruit ripening and coloring, and improving taste and quality! When planting plants indoors, lighting is indeed a problem, especially for plants that have a high demand for light. At this point, using plant lights to provide the necessary light energy for photosynthesis to plants is an ideal way, but many farmers may wonder if plant growth lights are useful? There is a reason for the problem. On the one hand, traditional plant lights have high power consumption, low lighting efficiency, and relatively short lifespan. LED plant lights are an ideal plant supplementary light source, breaking many limitations that traditional plant lights cannot break through, but the price is relatively high. There are Many Benefits to LED plant growth lights According to the latest market research report "Global LED Plant Lighting Market Share, Strategy and Forecast from 2015 to 2021", LED lights have lower costs and are more energy-efficient compared to other similar products. Therefore, LED lighting is rapidly being adopted. Due to the effective promotion of plant growth by LED lighting systems, LED plant growth lights are also widely adopted worldwide. Compared with previous high-pressure sodium lamps and metal halide lamps, LED plant growth light are more powerful, large, and efficient. They can save electricity and generate less heat. Less heat allows the plant light to be closer to the plants without worrying about them being burnt. The next generation of LED plant growth lights can activate a dramatic "power-saving mode", providing unparalleled product reliability. As demonstrated by the Everlight GL Flora LED plant lighting fixtures, LED plant growth lights are undergoing a transformation. They can accurately provide low-power, high-efficiency uniform light patterns and light distribution with appropriate wavelengths and color ratios, which are exactly what efficient photosynthesis requires. LED plant growth lights are different. Plant growth lamps can be used as artificial light sources for plant growth. The spectrum of the growth lamp is adjusted according to the needs of plant growth. The spectral range required for plant growth light is 400nm~700nm, ranging from blue light to red light. Horticultural lamps play an important role in the growth and development of plants. Plant growth is one of the functions of photosynthesis. There are three different ways in which plant growth lights work: Provide all the necessary lighting for plant growth Supplement sunlight during short periods of winter sunshine Increase the duration of "daytime" to promote special growth and flowering LED plant growth lights control plant growth by regulating lighting. The ability to consistently grow food locally represents a significant breakthrough for humanity. Growth lamps allow people to grow food indoors, and making full use of waste space is also an efficient way of producing food. Removing transportation costs from the food chain is also a major breakthrough. The ability to consistently provide fresh and hygienic food represents a significant shift in people's lifestyles and the achievement of quality of life. Growth lamps increase the density of food production by a factor of ten. This is of great significance. In certain places such as Japan, there are still shortcomings in the environment. The plant factory will continue to expand and use LED plant growth lights as large warehouse entities to provide food for the public and those in need of special nutrition. Susan Eustis, the main leader of the research team, said, "Solid state electronics will bring the same advantages to agriculture, just as it brings benefits to other industries. Growers have found that they can quickly achieve investment returns, using plant growth lamps can significantly reduce energy costs, prolong growth seasons, eliminate chemical pollution in food supply, and significantly reduce transportation costs in food production." As more and more people realize the importance of health and try to avoid the harmful effects of pesticides in food, greenhouse operators have found that plant growth lamps will have more potential markets. Large plant factories will focus on seedling cultivation work. Whether a plant lamp is useful or not depends on the correct use of the entire process before making a final decision. 1.when choosing a light, it is important to pay attention to the specific needs of the plants. If it is a light loving plant, buying a low-power ordinary plant light cannot meet the growth needs of the plants. If it is a shade tolerant plant, using a plant light that consumes too much energy is not cost-effective; In addition, if choosing LED plant growth lights, it is necessary to customize the lamp bead ratio according to the needs of the plants, and use the most energy-saving way to provide the best growth conditions for the plants. 2.Secondly, when using plant lamps, attention should be paid, (1)Regularly turn on and off plant lights, such as plants from 9am to 5pm, sunlight can meet the needs of plant growth, and the time for supplementing light can be around 7:00-9:00 and 17:00-21:00; (2)Set a reasonable lighting distance. If the distance from the plant is too far and the lighting is insufficient, the best plant supplementary lighting effect cannot be achieved. If the distance is too close to the plant, only local supplementary lighting can lead to uneven light reception of the plant, resulting in growth conditions not meeting expectations. 3.it is important to pay attention to the maintenance of plant lamps: following the instructions provided by the seller when purchasing plant lamps, installing, inspecting, and maintaining them may not be of great significance in the short term, but if they are not cleaned over time and are not cleaned in the correct way, it can cause significant harm to the lamp itself. Is LED plant growth light useful? Numerous studies by scientists and experiments by biologists have proven that LED plant lights are excellent plant supplementary light sources. You should know that red, clear, yellow, green, blue, and purple, the shorter the wavelength of the backward light, and the longer the wavelength, the more it can promote plant growth. Pink light is long wave light, which can promote plant growth and achieve supplementary lighting effects. In fact, you can use incandescent lamps or similar light to illuminate day and night, which is also long wave light. On the contrary, the light emitted by fluorescent tubes is short wave light. You can use two types of light together. In order to welcome the Olympics, Beijing has used this method to allow many flowers to bloom in advance. However, the composition of light is very complex. Plants have evolved for so long and have adapted to each component of light, with demands and dependencies. Therefore, the supplementary light you buy may only be able to supplement one aspect, and artificial lighting cannot fully imitate the effect of natural sunlight on plants. Just as no matter how good a perfume manufacturer is, it is impossible to completely simulate and produce a perfume with the fragrance of natural orchids. The best designer and manufacturer is nature. Moreover, different plants have different demands for light. Light can inhibit the growth of plant internodes, and this effect increases with the increase of light intensity and light duration. Therefore, seedlings are prone to internode growth and elongation under weak light and short light duration, while internodes tend to shorten under strong light and long light duration. Moreover, different light qualities can also affect the growth of seedlings and stems. Generally, red orange light is the most effective light for photosynthesis, which can accelerate the growth rate of seedlings, but the internodes are long and the stems are thin and weak; Blue and purple light can make seedlings grow shorter and stronger, among which ultraviolet light has the strongest effect on inhibiting seedling elongation and promoting seedling shorter and stronger. So, if you are a friend who is truly interested in plants or wants your own plants to grow better, there is actually no need to dwell on the question of whether LED plant lights are useful. Instead, you should understand the preferences of plants and master the correct lighting methods!

Some people say that if LED street lights are not powered by solar energy, they will have no further value for use; Some people also say that solar power supply will only make the production cost of LED street lights more expensive, making it difficult for LED street lights to be promoted and used in real society; Some people also say that LED street lights should be powered by a combination of solar energy and AC power There are different opinions. Now let's take a look at why solar LED street lights can replace AC LED street lights?

At present, most LED street lights still use AC power supply. On the one hand, the technology of AC circuit lights is already very mature, while solar street lights have many uncertain factors. On the other hand, the main consideration is still that the initial investment in solar energy is too large, thus ignoring many fundamental advantages of solar power supply.

The most important advantage of solar energy, as we all know, is that it is an inexhaustible and cleanest renewable energy source! It can truly solve the problem of global warming! It will ultimately replace all energy sources!

However, truly replacing all energy sources with solar energy is still a long-term and difficult task. Although solar energy is ubiquitous, its collection requires a certain amount of irradiation area. Obviously, the desert is the most ideal location, but long-distance power transmission and distribution will consume a large amount of expensive copper materials, and only large cities adjacent to the desert have trial value. It is difficult to find such a spacious and open place in large cities with high population density. Rural areas are limited by economic conditions and it is unlikely to be widely promoted now. It is best to start with small activities for any new things, and adopt a "self-produced and self sold" method. Street lights are one of the best pilot projects that first use solar energy. Moreover, energy conservation, like emission reduction, must first be advocated by the government, and even promoted through government subsidies like in Germany. Fortunately, the street lighting project was originally a government project and was tendered by the government. So government decision-makers must be aware that LED street lights will definitely replace high-pressure sodium lights, and solar LED street lights will also replace AC LED street lights.

Changing all street lights to solar street lights can save the power generation of a Three Gorges hydropower station

LED street lights are more energy-efficient than high-pressure sodium lights and have long been recognized by people. However, there may still be a lack of quantitative concepts. It is now recognized that 100 watt LED street lights can replace 250 watt high-pressure sodium lights, so it can be simply assumed that each LED street light can save 150 watts of electricity.

However, if solar power is used instead, even this 100W of electricity can be saved, which means that each street lamp can save 250 watts of electricity. According to relevant estimates, the total number of street lights in China is about 100 million or more, and it is growing at a rate of 20% per year. In 2008, 20 million new street lights were added. If these 100 million street lights can be converted into 60 million 250 watt street lights, and if all these 60 million street lights are converted into solar LED street lights, a total of 15 million kilowatts of power can be saved. Assuming that each street lamp works 12 hours a day, it will save 65.7 billion kilowatt hours of electricity within one year. The total power generation of the Three Gorges Hydropower Station in 2007 was 61.603 billion kilowatt hours. Therefore, the electricity saved by converting all streetlights nationwide to solar streetlights will exceed the annual power generation of a Three Gorges hydropower station. This is an extremely astonishing number.

Moreover, solar energy is a clean and renewable energy source that not only saves electricity but also reduces carbon dioxide emissions. Each 250 watt high-pressure sodium lamp will produce 1290 kilograms of carbon dioxide within a year, so converting all 60 million street lamps to solar powered ones will reduce 77.4 million tons of carbon dioxide. So after switching to solar energy, not only did it save electricity costs, but it also saved the cost of reducing carbon dioxide. The reduction cost per ton of carbon dioxide is $345-404. Reducing 77.4 million tons of carbon dioxide is equivalent to saving $31 billion in carbon dioxide reduction costs!

The preceding numbers are just a comparison between LED street lights and high-pressure sodium lights. For both 100W LED street lights, the energy-saving comparison between using AC power and using solar energy can be obtained by dividing the above data by 2.5. That is to say, if all 60 million 100 watt LED street lights are powered by solar energy, they can save 26.28 billion kilowatt hours of electricity compared to when all AC power is used, and the cost of reducing carbon dioxide emissions is 12.4 billion US dollars.

The efficiency of AC power supply will be 15% lower than that of solar power supply

Because when using AC power supply, a switch mode power supply must be used to convert it into DC. The efficiency of a typical switching power supply is about 80%. So for a 100W LED street light, its AC input power is approximately 120W (120W is used in the comparison table below). When using solar power supply, as long as a DC/DC constant current source is used, its efficiency can reach up to 95%. Therefore, the total efficiency of using AC power is about 15% lower when combined. So the above numbers should be increased by 15%.

AC power supply and power factor issues

In relatively low-end switch mode power supplies, the lack of power factor compensation will lead to a decrease in the overall efficiency of the power grid if widely adopted.

The biggest problem with using AC power supply is reducing the lifespan of the entire lighting fixture

Because alternating current must be rectified and filtered to become direct current, electrolytic capacitors must be used for filtering in all switching power supplies. As is well known, the lifespan of electrolytic capacitors is very low, with a typical lifespan of only 1000 hours and a long-lived lifespan of only 10000 hours. Moreover, for every 10 degrees increase in ambient temperature, the lifespan decreases by half. In high-power LED street lamps, the temperature rise is very high, so the lifespan of electrolytic capacitors is also shorter. The usual requirement for the lifespan of LED street lights is over 50000 hours. The lifespan of the entire lighting fixture will inevitably be affected by the short lifespan of the electrolytic capacitor. It can be considered that many low-quality LED street lights in the past quickly failed, not only because the heat dissipation problem of the LED itself was not properly handled, which accelerated its light decay, but also because the failure of the electrolytic capacitor in the AC power supply was an important factor. In solar powered systems, there are no electrolytic capacitors. So the lifespan of its constant current source can be guaranteed to match the lifespan of the LED.

The overall cost of solar powered LED street lights is much lower than that of AC powered LED street light systems

Although the initial installation cost of solar street lights is higher, the cost of laying AC power cables and long-term electricity bills is much higher than that of solar systems. Let's do a detailed analysis below.

(1) The cost of LED lamp holders and poles for the two systems is generally the same, with the main difference being the solar panels. The power of solar panels is usually about three times that of LED lighting fixtures. If the LED is 100 watts, then a 300 watt solar panel is required. At present, the price of solar panels has been reduced to 23 yuan/watt, and 300 watts is 6900 yuan. In addition, solar systems also require batteries, but their cost is equivalent to the cost of switching power supplies in AC power supply. So the two can offset each other. So the main difference in the cost of the lighting fixtures themselves is the solar panels.

(2) The maximum expenditure for the initial installation of AC powered LED street lights is the laying of cables. Most people think that the main cost is the cable itself, but in addition to the cable itself, its laying, auxiliary facilities (inspection wells, distribution equipment), etc., are much more expensive than the cable itself. Assuming a 10 kilometer long road as an example, with one LED street light placed every 30 meters on the opposite side, a total of 666 LED street lights are needed. If solar street lights are used, the cost can be recovered within five years and an additional 430000 yuan can be saved. After five years, the annual electricity bill can be saved by 1.22 million yuan.

AC circuit lights and cables are the best targets for theft

This is no longer sensational news. Reports of street light cables being stolen can be seen everywhere online. Only Changfeng Avenue in Wuhan has been in operation since 2005, and more than 36000 meters of cables have been stolen. A total of 1900 kilometers of street light cables have been stolen in Hangzhou, of which 140 kilometers have been stolen. Even the street light cables on the Shanghai Inner Ring Road and the Shanghai Nanjing Expressway have been stolen. Even the street light cables on the Fifth Ring Road in Beijing are often stolen. It can be seen that this kind of thing does not only happen in remote and impoverished areas, but is a common occurrence everywhere. Perhaps it is because the voltage of the street light cable is relatively low, the current is relatively high, the cable is relatively thick, and the copper content is relatively high. This is an important issue that must be considered when choosing AC power supply.

The safety of AC power supply is a hidden danger

In addition to posing a personal safety hazard to thieves who steal cables and appliances, it can also pose a certain safety hazard to nearby farmers digging soil.

AC power supply may also pose safety issues for equipment

AC power operates online, and due to lightning strikes and other reasons, high-voltage surges often occur online, posing a certain threat to the safety of equipment.

Solar LED street lights, on the other hand, do not have the aforementioned drawbacks at all. Their composition is very simple and consists of only five parts:

How can solar LED street lights replace AC LED street lights?

And its installation is very simple, just make a cement base, stand up the lamp pole, and install the foundation screws. Especially, there is no need to trouble the power system personnel to design, install and construct, dig trenches, lay cables, dig inspection wells, install transformers, etc. This is a very important advantage.

Shortcomings of solar street lights

Some people are concerned about the environmental pollution caused by lead-acid batteries. In fact, the largest user of lead-acid batteries is automobiles. Currently, China produces and sells 7 million cars annually, and each car uses at least one lead-acid battery. And lead-acid batteries in cars have long had a very complete recycling system, in which the lead plates will be recycled and regenerated. So the lead-acid battery in the solar street light system can be fully utilized by the car's recycling system without causing environmental pollution. Moreover, the cost of lithium batteries has now been reduced to the point where they can be practically adopted*** A company that produces solar LED street lights (KESC) has developed street lights using lithium iron batteries. There are also factories in Dongguan, China that produce lithium-iron automotive batteries. It can be guaranteed for five years.

The only issue with solar street lights currently is the cost of solar panels, but their prices are currently decreasing at an astonishing rate. In 2008, it had already reduced its price by one-third. The price of its main raw material, polycrystalline silicon, has decreased from $300 per kilogram in 2007 to $200 in 2008. It is expected that the price of polycrystalline silicon will decrease to $100 per kilogram by 2009. Especially in China, the production of polysilicon is growing rapidly. After all 33 ongoing projects are put into operation, the production will reach over 146000 tons, while the current domestic demand is only 8000 tons. Therefore, how to expand domestic demand is the top priority. Vigorously developing solar LED street lights is undoubtedly the best way.

In summary, the use of solar energy in street lights has many advantages but no disadvantages. Why not do it? Do you still doubt whether solar LED street lights have the power to replace AC LED street lights now?

LED street lights refer to street lights made from LED lighting fixtures, which have unique advantages such as high efficiency, safety, energy conservation, environmental protection, long service life, fast response speed, and high color rendering index. They are of great significance for energy conservation in urban lighting.