What factors to consider when choosing the LED garden lighting system? How to achieve energy efficiency?

In the light of horticultural lighting enterprises, will face a number of considerations, including: light intensity, spectrum, light distribution uniformity, energy efficiency and service life of the lamp. Garden lighting system can be converted to electrical energy for growth and development of plants, promote the photosynthesis of light, and the light source based on LED can provide for the application of frequency tuning. However, the determination of solid-state lighting (SSL) system efficiency or effectiveness is a challenge. There are several factors that affect the overall efficiency of the lighting system. This paper discusses how to design the lighting effect of energy efficiency, energy efficiency and how to influence the controlled plant growth environment overall profitability.

In fact, garden lamp converts electrical energy into light effect available for plant growth in a controlled environment agriculture (CEA) success. Figure 1 is a controlled environment agriculture (CEA) is an example of a vertical farm.

Figure 1. the lighting solution is installed in the crop canopy within a few inches is the vertical agricultural application breakthrough. With poorly designed LED solutions and other lighting technologies (such as HPS and fluorescent lamps) compared to a properly designed LED solution can achieve higher yield per square foot.

Relevant indicators of gardening

The main use of plant photosynthesis in 400-700nm wavelength of visible light (Figure 2), therefore, this section is often referred to as photosynthetically active radiation (PAR). Photosynthetic photon flux (PPF) of total PAR production per second measurement of lighting system. When measuring, using integral ball, for almost all photon capture and emission measurement of lighting system. The PPF unit is Moore per square meter per second photon number (mol/s).

Figure 2. to photosynthetically active radiation (PAR) the average response of plants

Photosynthetic photon flux density (PPFD) measurement of PAR content of the plant canopy at. PPFD said the area and per unit time in the wavelength range of visible light photons number, unit is mol/m2/s. PPFD also said the number of photons and the correlation between photosynthesis.

Finally, we discuss the effect of photon. Effect of horticultural lighting system refers to the photon is converted to electrical energy efficiency PAR photon. If the PPF and input optical power are known, the photon effect can easily calculate horticultural lighting system. The given PPF units for mol/ s, the measurement unit is Watt joule per second (J/s), the number of seconds in the numerator and denominator elimination, the unit of mol/ J, this unit is used to that effect. The higher the number, said lighting system converts electrical energy into PAR photon is more effective.

The common method of horticultural lighting

Next, we have to understand the nuances of lamp design, and the reasons for such horticultural lighting system. The world horticulture lighting system is the most commonly used high intensity discharge (HID) based on the lighting and HPSL (HPS). High pressure sodium lamp was not specifically designed for planting plants, is designed for light rail and parking. However, ready availability and high output level to be widely used in gardening, because they provide very high light intensity, most of the light emitted in the 565-700 range of nm, the effective band can accelerate photosynthesis.

A disadvantage of using high pressure sodium lamp for horticultural lighting is to produce a lot of heat radiation. The surface temperature of the high-pressure sodium lamp can reach more than 800 DEG F temperature (about 430 DEG C), so between the plant canopy and HPSL must have sufficient distance to avoid damage to plant tissue. Mounting height of luminaire, inverse square law began to take effect, it can reduce the rate of lighting. With the passage of time, increase the energy efficiency of high pressure sodium lamp, HPS lamp and double end, photon can achieve 1.7 mol/J performance.

Turn to LED

We review the use of LED in the process of horticultural lighting. In 2014, the highest efficiency LED horticulture lighting system and double end efficiency as high pressure sodium lamp. Compared with the LED high pressure sodium lamp, long service life (L70 = 50000 hours) that many growers use LED instead. However, compared with the high pressure sodium lamp, LED garden lighting system cost is relatively high, limiting the transition to LED lamp.

LED chip manufacturers have improved the existing component effect in the past few years, so that they can significantly improve the efficiency of photon, and every year to continuous improvement. In fact, based on gardening LED lighting system now can be realized than the photon efficiency of double end high pressure sodium 45%. Although the efficiency of individual components to improve the efficiency of LED garden lighting, but it is also a variable LED over high pressure sodium lamp.

LED heat system

About LED lighting the heat generated when there is a common misunderstanding. Many growers think that LED produces less heat than high pressure sodium lamp, the LED lamp with low wattage when driving is really. If there is a 600W LED and a 600W double end lamp high pressure sodium lamp, from a macro point of view, they generate heat in roughly the same range.

The main difference between LED and high pressure sodium lamp is how many of the two 600W PAR generated energy, how to heat from the lamp in the. Most of the heat from the high pressure gas lamp down radiation to the crop canopy, and most of the heat is LED in components and the printed circuit board (PCB) generated by the connecting parts, heat is usually transmitted to the PCB, may also be the heat sink, and by removing the upward convection.

Therefore, LED is one of the main advantages of horticultural lighting system can be placed in the vicinity of plants and can make plants from heat radiation damage. However, if no heat through the heat management system appropriate for effective removal of PCB from the LED, the life of the components will be significantly reduced