What are the design requirements for solar LED lighting systems?

What are the design requirements for solar LED lighting systems?

Solar energy is a clean energy with many advantages, but it also has great shortcomings: large dispersion, low density, and light intensity is greatly affected by seasons, climate and environment, so how to use solar energy efficiently has always been a problem that plagues people’s design. In order to improve the utilization rate of solar energy, in addition to improving the efficiency of the system components themselves, improving the matching efficiency between the components of the system is the key to improving the reliability and efficiency of solar LED lighting systems.

The structure of the solar LED lighting system is relatively simple, mainly composed of the following four parts: solar cell array, controller, battery and LED lamps. The solar LED lighting system has different application forms, ranging from solar lawn lights of 0.3~2W to advertising light boxes of several hundred watts, but its composition and working principle are basically the same. Figure 1 shows the basic structure of a typical solar LED lighting system. The characteristic of the system is that the LEDs in the system can be directly powered by 12V DC, so there is no need to use inverters and other equipment. The whole system has a simple structure and is easy to operate. However, most solar LED lighting systems currently use independent structures, so the mutual matching of various components of the system directly affects the operating performance and reliability of the system.

Figure 1 - Basic structure of solar LED lighting system
Figure 1 – Basic structure of solar LED lighting system

(1) The specific requirements of each component of the solar LED lighting system in the design and application

①Solar cell array
The solar cell array is the power supply system of the system. The main purpose of its design is to generate enough electrical energy to meet the needs of the system power consumption. The design content includes the power and inclination of the cell array.

The battery stores the energy of the solar cell array and uses it when it is discharged at night. The purpose of the design is to store enough energy to ensure the energy consumption of the system. The design content is mainly for the selection of capacity and charge and discharge performance.

The main function of the controller is to control the charge and discharge, protect the overcharge and discharge of the battery, and adjust the system to ensure the reliability of the system operation.

④LED lamps
LED lamps include power supply design, lamp head design and structural design. The main purposes of the design are: to drive the LED to work normally and stably, to design a reliable structure to ensure that the system can be placed safely, and to design a reasonable light distribution to meet the lighting requirements.

Including the design of the power distribution equipment and the placement of the battery, usually a system with a slightly higher power needs to set up a power distribution box and bury the battery as a base, and a low-power system can also be integrated on the lamps.

When designing the system, the required power can be determined according to the requirements of lighting, and then the power of the solar cell array can be determined according to the power of the load, and finally the energy of the battery can be determined. In actual design, mutual verification can also be performed to obtain better performance.

(2) Design requirements for the LED lighting system at the project site

When designing a solar LED system, a fixed configuration cannot be used in different places, and it is usually necessary to collect data on the project site for special design to get better results. Therefore, the information on the project site is very important to the design of the solar LED lighting system.

①Project requirements for lighting conditions This includes requirements for light distribution and photometry, which directly affects the selection of lamps and the power of light sources. The efficiency of the luminaire directly affects the power of the light source, and the power of the light source directly determines the energy consumption level of the entire system. Therefore, the power of the light source selected to meet the engineering requirements will determine the design parameters of the entire system.

②The requirements of the project for lighting time If the project requires a long time for lighting, the energy consumed every day will be large, which requires a solar cell array with high power to provide sufficient charging energy, and the requirements of the battery are also increased accordingly.

③The solar radiation situation of the project site needs to know the geographical location of the project site, including location, latitude, longitude and altitude; meteorological data of the area, including monthly total solar radiation, direct radiation and scattered radiation, annual average temperature And the highest and lowest temperature, the longest continuous rainy days, the maximum wind speed and special meteorological conditions such as hail, snowfall, etc. These parameters are very important to the independent solar system, and a reasonable inclination and azimuth of the solar cell array can be designed.

④Allowable continuous rainy days The length of the continuous rainy days that the solar LED system needs to work directly determines the size of the battery capacity. The continuous rainy days must increase the capacity of the battery, and the power of the solar cell array needs to be increased accordingly to ensure that the battery can be filled.

(3) Design content and matters needing attention

The design of solar LED lighting system can be divided into two levels: hardware design and capacity configuration. The main purpose of hardware design of solar LED lighting system is to select suitable hardware according to the actual situation. The equipment includes LED lamps, solar cell array selection, bracket design, inverter selection, cable selection, control measurement system design, Lightning protection design and power distribution system design, etc. The main purpose of the solar LED lighting system capacity configuration is to calculate the number of solar cell arrays and batteries required for the system to work reliably throughout the year. At the same time, attention should be paid to the relationship between the maximum reliability, reliability and system cost of coordinating system work, and the system cost should be reduced as much as possible on the basis of satisfying the maximum reliability of system work. When designing the system, it is necessary to comprehensively consider the hardware design and capacity configuration of the system.

In the specific design, it is necessary to take into account the comprehensive situation of the project site for debugging, so that the system can achieve the optimal effect. The specific precautions are as follows.

① Changes in solar radiation at the engineering site. Many solar radiation data are the total annual radiation. In fact, there are certain changes every year. The ideal situation is that the daily radiation is constant, but the actual radiation is very variable. Therefore, when designing the solar cell phalanx, it should be possible to generate the maximum amount of electricity when the solar radiation is the weakest.

② The charging, discharging and energy storage of the battery are greatly affected by the environment of the project site. In a relatively high-power system, the substrate should be buried as much as possible, which can reduce the impact of environmental changes on the battery.

③The electronic devices of the system also need energy consumption. The heat dissipation of components, especially the heat dissipation of LEDs, needs to be fully considered, and reasonable heat dissipation is designed to ensure the normal operation of the devices and reduce energy consumption.

④The topography of the project site will sometimes affect the reliability of the system operation. The design should avoid blocking as much as possible, and special design should be carried out in the unavoidable area.