LED Grow Light Spectrum

This is a series of articles about plant lamp technology.

First, LED grow light spectrum

The basis of light research is spectrum. The application quality of light requires spectral analysis. The spectrum of LED plant lights is especially important. The The led grow lights manufacturer’s ability to design the spectrum of plant lights determines its market position. The spectrum of LED plant lights needs to be specially designed according to the planting process. To imitation.

The plant factory is a cross-border product. The research institute of the plant is divided into planting equipment technology and planting technology. The plant lamp spectrum technology is an important link between planting equipment and planting technology. It is necessary to clarify the planting process. Spectral design, the design and manufacture of plant lights is to ensure the best efficiency of the light quality required by the planting process. These characteristics of plant lights determine the complexity and diversity of plant spectral design.

1. Non-visual application of spectrum

Spectral applications are divided into visual applications and non-visual applications. Lighting is a visual application. Plant illumination is a non-visual application. Visual applications and non-visual applications have different physical dimensions. However, many plant lights are still used in lighting units. Labeling parameters, which can lead to cluttered parameter annotations, may come from the reference to “plant lighting.”

The spectral study of plant photosynthesis is based on the distribution of optical radiation power or photon of the wavelength domain (spectral mass), which is achieved by spectral data and spectrograms.

1.1 Solar spectrum

Planting requires studying the solar spectrum. The solar spectrum tested on the ground belongs to the absorption spectrum. The standard solar spectrum is shown in Figure AM1.5G (G173-03). Due to the geographical location and season, the amount of spectral radiation measured on the ground will be There are differences, but the morphology of the spectrum is the same.     

Plant photosynthesis, the general theory is to study the wavelength range of 400nm-700nm, the wavelength is limited to this range of AM1.5G (below) can be seen, the spectral shape is close to rectangular.

In order to provide a spectral design reference for an artificial light source, we give an AM1.5G map with a wavelength in the range of 350-850 nm for reference.

The solar spectrum has an important reference for the spectral design of plant lights, but it does not have dependence. Trying to imitate the spectrum of sunlight to plant lights is a futile and inefficient approach.

The ratio of red, green and blue radiation of AM1.5G in the wavelength range of 400-700nm is:

Red light accounted for 32.62%, green light accounted for 35.38%, and blue light accounted for 32.69%.

Analysis of the sunlight in a given area is important for planting in the area and should be measured locally by professional instruments so that it can be accurately analyzed. The picture below shows the relative spectrum of Foshan Nanhai in September 2013.

The ratio of red, green, and blue radiation in this spectrum in the 400-700 nm wavelength range is:

Red light accounted for 28.7%, green light accounted for 36.58%, and blue light accounted for 35.43%.

It can be seen that the geographical location is different, the red, green and blue components in the spectrum are different, which has a great influence on the design of solar-type and hybrid plant factories.

Accurate analysis of the local solar spectrum can provide a scientific photosynthetic reference for the planting process of solar and hybrid plant factories, which can correctly provide the basis for the replacement of the fill lamp, for the solar plant factory, accurate spectrum Analyze the way that is more conducive to SPA.

It should be noted that the spectrum of the solar spectrum is different from that of the artificial light source. The solar spectrum is suitable for the description of the radiation dimension, and the artificial light source is suitable for the description of the quantum dimension. For this problem, a special article is introduced.

1.2 Spectrum and limit parameters of LED light source

The spectrum of the LED plant lamp is mainly discussed because the spectrum of the LED light source can be designed according to the planting process requirements. At the same time, the spectrum of the LED light source can realize the control of the variable spectrum through the dimming technology, and the LED light source is currently the only one that can be realized. The variable spectrum of plant light source, the plant light variable spectrum technology is mainly for light form control, and has little effect on energy saving. The ordinary plant lamp can also save energy through the adjustment of the photoperiod, and the application cost of the variable spectrum will be much improved.

1.2.1 The highest PPF can be derived from the spectral shape of the LED

The spectral shape of the LED source is shown in the following table:

After the spectral shape of the plant lamp is determined, the highest YPF or PPF corresponding to this spectral form can be calculated, which is very important for evaluating the application of LED plant lights, and is also the main method for comparing the performance of LED plant lights with other types of plant lights. You can refer to the table we made:

Spectral shape and electric
power of LED light source

Actual measurement
YPF  (umol/s)

Radiation efficiency35%
YPF  (umol/s)

Radiation efficiency40%
YPF  (umol/s)

Spectrum with a wavelength of 445nm
P=1.12   (w)

1.505

1.5102

1.7227

Spectrum with a wavelength of 660nm
P=0.784   (w)

1.2238

1.5058

1.72

Spectrum with a wavelength of 3000K
P=0.48   (w)

0.6118

0.8394

0.9557

Blue + Pink  P=0.48   (w)

1.2595

2.1602

2.4698

Red blue light  P=24   (w)

43.61

44.3685

0.8152

This article only lists some of the spectra, more content will be shared in the “Plant Light Spectrum Technology Forum”.

The current LED package technology delivers the highest radiation efficiency of less than 40% in volume.

Radiation efficiency of light source = (radiation power / electric power) × 100%

1.2.2 The spectral design of LED plant lights reflects the manufacturer’s quality capabilities

The spectral design of the LED plant lamp is the equipment support capability required for the planting process. It is related to the market competitiveness of the plant lamp manufacturer. It is the main feature to measure the technology and process of the manufacturer. The spectral design of the plant lamp reflects the manufacturer’s LED chip. With the choice of packaging, plant lamp spectral analysis and calculation capabilities, luminaire design, light quantum field uniformity control, drive technology, heat dissipation technology, product reliability control, installation structure design, etc., marking the manufacturer The technical strength of the products in the market, the application of the above aspects to evaluate plant lamp products can reduce investment risks and procurement risks.

2. Spectral design points of LED plant lights

The spectral design of the LED plant lamp is the technical expression ability required for the planting process and reflects the manufacturing qualification of the manufacturer.

2.1 Plant lamp manufacturing process affects PPFD value

Usually, the planting process needs to propose a daily radiation amount based on a certain light quality, or a PPFD value of the planting surface (some planting processes require YPFD values) and a photoperiod, which determines the PPFD value and photoperiod, and the designer according to the PPFD value. Calculate the PPF value (or YPF value) of the LED light source, and then perform the spectral design; here, it should be noted that under the same light source PPF value, different light distribution design, heat dissipation design, and drive design lead to significant differences in PPFD values. The manufacturing process has a great influence on the power utilization efficiency of the plant lamp. This effect can be measured by the PPF value and the PPFD value of the electric power per watt. The higher the value, the better.

For the LED light source: PPF/w, for the planting surface: PPFD/w, comparing the two indicators of the plant light of the same spectral form, the manufacturer’s manufacturing process level can be evaluated.

2.2 Plant lamp spectrum is not the best, only the most suitable

Because the spectrum of LED plant lights can be designed, the spectrum of LED plant lights shows diversity. The spectrum of each plant light is best advertised by designers. Here we emphasize that the spectrum is not the best, only the most suitable. A certain planting process, attempting to make the LED spectrum universal is not a good design idea, and the high compatibility spectrum design is at the expense of planting efficiency and wasting power.

2.3 Focus on the radiation field uniformity of the radiating surface

For a variety of single-wavelength lamp-bead combination plant light spectrum, the uniformity of the radiation surface after mixing a variety of radiation needs to be considered, mainly the arrangement of the lamp bead, the light distribution design, the installation height of the lamp, etc.; the uniformity of the radiation field Influencing the photosynthetic efficiency, for the three-dimensional planting of the shelf structure, the Langmu light distribution is used as much as possible. For the greenhouse-filled plant lamp with the lens, the uniformity of the radiation field needs more attention. It is necessary to improve the radiation by increasing the installation height. The result of face uniformity is to reduce the PPFD value at the 2nd power rate of the distance.

2.4 Focus on the efficiency of plant lamps

The lamp efficiency of the plant lamp is the ratio of the PPF value of the lamp to the PPF value of the light source. This value is less than 1, which is related to the secondary optical distribution design. The efficiency of the LED plant lamp is usually between 0.9 and 0.5, and the efficiency of the lamp affects the plant. The energy consumption index and planting efficiency of the lamp, the efficiency of the plant lamp with lens design will not exceed 0.8.

2.5 Weighting of plant lamp spectra

Plant lamp spectral weighting (RQE) can better solve the contradiction between plant absorption efficiency and energy consumption. The same as the visual effect function of illumination is the absorption efficiency function of plants (also called action curve). The spectral weight of some plant lights is Use the Mokley curve (below) or Japan’s tendency to increase the plant’s correction curve based on the Mokley curve (below).

Mokley curve


Japanese correction curve

It should be noted that Mokley’s research is not the use of LED light sources. At the same time, Mokley’s research is based on low-radiation and a few varieties of indoor and outdoor comprehensive planting data, although the Japanese correction curve adds plant varieties, but The above problems still exist. Compared with the German industrial standards, their weight is in the blue light. We believe that these weights are not completely suitable for the LED light source. The spectral V-weighting (slightly) for the LED light source is only a The idea, how to weight the spectrum is still the direction of research in various countries.

TEST REPORT

Item

Content

Description

Product specifications
and identification

2835 200pcs

Based on sample label

Electric power (w)

18.2

Product configuration drive power

Optical radiation power (w)

5.2733

Wavelength range:  380nm-800nm

Radiation efficiency Pr (w)

0.28974

Wavelength range:  380nm-800nm

Luminous flux  ( Pr/P)

7.22.499

Wavelength range:  380nm-800nm

Luminous efficiency (LM)

39.6977

Wavelength range:  380nm-800nm

Peak wavelength (lm/w)

655

 

PPF (μ  mol/s  )

22.358

Wavelength range:  400nm-700nm

PPF / w (μ  mol/s.w  )

1.2285

Wavelength range:  400nm-700nm

Uncorrected YPF

28.075

Wavelength range:  380nm-800nm

Ultraviolet radiation powe(w)
and radiation content

0.0000558   

0.0011%

Wavelength range:  380nm-399nm

Blue radiant power(w) and
radiation content

0.50991

9.6698%

Wavelength range:  400nm-499nm

Green radiant power(w)
and radiation content

0.62578

11.8671%

Wavelength range:  500nm-599nm

Red radiant power (w)
and radiation content

3.1774

60.2551%

Wavelength range:  600nm-699nm

Infrared radiation power (w)
and radiation content

0.9601

18.2070%

Wavelength range:  700nm-800nm

2.6 About spectral ratio

So far, many plant lights are still using the ratio of the lamp to the ratio of the spectrum when talking about the spectral ratio. Since the lamp bead ratio cannot reflect the amount of radiation, this problem needs to understand the specifications of the LED chip. The LED chip is according to the same chip size. The radiant power is divided into grades and supplies. The LED spectrum provided by the lamp-bead ratio may have a 30% deviation. This is one of the reasons why the different batches of the same product have different planting effects. The correct spectrum is matched. The ratio of the radiant power ratio of the RGB band according to the wavelength range of PAR is such that the product provided will have data basis. The following is the data analysis of a product for your reference.

2.7 Need to add spectrum of UV and IR bands

Increasing the spectrum of UV and IR segments, the planting process is mainly to control the light form of plants. For LED plant lamps with increased UV and IR segments, it is not appropriate to use micromolar expression in UV and IR segments, but to use radiation parameters. Expression, while providing PPF and YPF values, otherwise, the UV and IR radiation requirements of the implant process cannot be correctly expressed.

3.clear planting process determines the spectral design of plant lights

The design of plant lights is based on the planting process. If the daily radiation of lettuce is too large, it will lead to physiological calcium deficiency, and photoinhibition may occur. Reasonable combination of daylighting is very important. Planting techniques include: plant photosynthesis. The amount of daily radiation and the total amount of radiation in the planting cycle, plant species and provenance, and whether LDP or SDP, planting methods and substrates, planting environment and control; for plant light spectrum and daily radiation closely related to planting, first Determined by the planting process of planting varieties, in the design specification of the research institute of Haoliang Solid Light Source, we adopt the planting process expert system. The daily radiation amount of plant planting in the system determines PPFD and photoperiod, PPFD determines PPF, PPF determines plant Lamp design and art, PPFD determines the installation height and quantity of lamps, PPDF also determines the amount of ventilation and carbon dioxide supplement, these parameters can be calculated by calculation, through the total amount of radiation can be derived from planting costs; here can be seen, the spectral shape and The amount of radiation (light quality) first needs to determine what environment to use to plant what varieties Correct design of the spectrum of LED plant lights, plant planting process is an intrinsic factor that closely links agricultural planting with industrial control. Therefore, the spectral design basis of plant lamp can only be derived from the planting process requirements.

Regarding the planting process, we will conduct further analysis in the Plant Light Spectroscopy Technology Forum.

3.1 Hybrid greenhouse fill light

For greenhouse planting and hybrid plant factories that use a combination of sunlight and fill light, it is accurate to perform a natural field radiation field spectral analysis to determine the amount of fill light. For sites where conditions are not analyzed, the illuminance value can be tested. The average value, by dividing the average value of the illuminance by 55, can be used to obtain the PPFD value of the planting surface under sunlight, and use this value to determine the amount of light supplemented by the plant lamp. This simple method is very useful for project planning and cost accounting. The greenhouse fill light can reduce or eliminate the green light band. Whether it needs to be supplemented by green light radiation needs to be determined by measuring the amount of green light radiation from direct sunlight and scattered light. Regarding the mechanism of action of green light radiation on plant cultivation, we will The Light Spectrum Technology Forum was featured.

3.2 Spectra in a fully artificial environment

Planting in a fully artificial environment, although the red and blue light has a significant effect on the cultivation of leafy vegetables, the taste of hydroponic vegetables is still the key to improving the quality of vegetables. We recommend using white light plus red light spectrum, completely Spectral design in artificial environment requires comprehensive consideration of carbon dioxide concentration, ventilation, ambient temperature, substrate or nutrient solution control, shelf structure design and other factors. Many stacked three-dimensional planting in order to increase the number of planting layers and minimize nutrient solution tanks Height, this method will reduce the balance of nutrient solution and affect the absorption efficiency of the spectrum. The important goal of spectral design under complete artificial environment is the quality control of planting, but the planting process of plant growth is not competitive in the market.

4. About the full spectrum

Some LED plant lights are nominally full spectrum, and may be intended to express their rich spectral content. There is a key concept here, that is, how is the definition of “full” of the full spectrum defined by whom, in the end of the wavelength range? Width can be called “full”, although the spectrum of sunlight is the most comprehensive, when studying plant photosynthesis under solar illumination, the PAR value is only described in the range of 400nm-700nm, many nominal full spectrum LED plants The lamp is supplemented with UV and IR partial bands, but PPFD is used to express the parameters. Since PPFD does not describe the amount of UV and IR radiation, the parameter description of this full-spectrum plant lamp shows a low-level error. We believe that the wavelength range of the plant lamp It is only the domain of the spectral absorption efficiency function, not the value range of the absorption efficiency function. The absorption efficiency of the spectrum is an indicator for measuring the effect of photosynthesis. The broad-band or multi-band spectrum is called the full spectrum and cannot represent the plant light. Effectiveness and compatibility, the use of full-spectrum representation of plant lights is not rigorous and often misleads the applicator’s application; the wavelength range of the spectrum is still set with Planting process is related to the planting process to determine the domain of spectral design, rather than planting based on the spectrum. Plant lights and plant factories are cross-border products. Some phenomena are industrial people busy researching planting, and agricultural people are busy studying spectra and knowledge. The extension is only for communication and understanding. The professional cooperation and professional division of spectrum design will help the industry to improve rapidly.

5. Complexity of plant lamp spectroscopy studies

For the LED light source, the same PPFD value, the spectral shape can be different; the same PPFD, the secondary optical design requires different ppf values; the same ppf value, the efficiency of the luminaire is different, the PPFD value is also different; ppfd is the same, The morphology of the spectrum is not correct, and the planting efficiency is different; even if the above conditions are the same, the plant sources are different, the growth environment is different from the substrate, and the planting effect is different; in addition, the same LED plant lamp is also subject to carbon dioxide concentration, ventilation, Environmental factors such as temperature control affect the planting effect. Under the planting efficiency and quality meet the requirements of planting process, it is very important that the plant lamp needs the manufacturing process to ensure that the energy consumption index is minimized. The complexity of the spectral research shows that the current The diversity of plant lights, because there is no evaluation standard at present, the plant lights on the market are all blooming, and hundreds of families compete.

6. Cooperation with professional technology is the best way to improve the industry

Plant lamps involve a wide range of technologies and are cross-border products. No matter how strong the funds are, it is difficult to integrate multidisciplinary talents from the perspective of development costs. Enterprises need to start from their own conditions and solve technical and cost problems. More importantly, It is to solve the technical support problem of after-sales products. For cross-border products, the mature experience is the road of cooperative development; the agricultural people research the good planting process, this is the key to the success of plant lamps and plant factories, and the industrial people do well in accordance with the requirements of planting process. Equipment, this affects planting costs and economic benefits, professional cooperation can promote the rapid development of new

agricultural planting with controllable artificial environment;

Radiation field analysis

Plant lights and lighting are different. The application of lighting products is the end customer, which can be used for marketing with concepts and forward-looking. Plant lights are only tools for agricultural planting. Whether the effect is not described by propaganda can be described by actual application. Whether the application of plant lamp can achieve the expected effect is not only the problem of the plant lamp itself, but also related to other technical factors. It is necessary to provide reasonable technical solutions. The marketing of plant lamp belongs to the technical means of technical support as the main means of marketing. Cases often reflect successful technical services. In the absence of technical standards, providing technical solutions is critical and companies need to face them seriously.

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