In the era of global energy transition and environmental protection, solar streetlights have gradually become a star product in the lighting field due to their excellent characteristics. These street lights not only light up the streets and alleys, but also bring a new lighting experience for various scenes with its energy-saving, environmental protection and economic advantages.
Advantages of solar street lights
(1) energy-saving pioneer
The energy source of solar street lights is solar energy, which is a clean, renewable energy. During the day, the solar panels on the top of the street lamp through the photovoltaic effect, the photons in the sunlight into electrons, thus generating direct current. A monocrystalline silicon solar panel of 1 square metre in area with a conversion efficiency of 20%, for example, can generate about 200 watts of electricity per hour under sufficient light conditions. This type of energy conversion greatly reduces the reliance on traditional thermal power and effectively lowers carbon emissions. According to statistics, a 30-watt solar street lamp can reduce carbon dioxide emission by about 100kg a year, which is equivalent to the carbon absorption of five adult trees.
(2) Cost-effectiveness
In terms of installation cost, although the initial investment of a solar led street light may be slightly higher than that of a traditional street light, the advantage is very obvious when considering the long-term operating cost. Traditional street lights need to lay cables and connect to the power grid, which involves high construction costs and subsequent electricity expenses. Solar street light adopts integrated design, without complex wiring project, easy to install. In the operation phase, solar street lights have almost zero electricity expenditure. Take a small community with 100 streetlights as an example, if traditional streetlights are used, the annual electricity expenditure is about RMB 50,000; while with solar streetlights, there is almost no extra energy cost except for a small amount of maintenance cost. Moreover, due to the relative simplicity of the structure of solar streetlights and the small number of components, the maintenance cost is much lower than that of traditional streetlights, which can generally save about 30% - 50% of the maintenance cost.
(3) Durable
Solar street lights in the design of the full consideration of a variety of harsh environmental factors. The lamp body is usually made of high-strength aluminium alloy, which has good anti-rust and corrosion resistance. The lampshade is made of PC material with high light transmission and impact resistance, which can effectively resist the erosion of rain, sand and ultraviolet rays. In addition, the waterproof rating of solar street lights is generally up to IP65 or above, which can work normally even in heavy rainy weather. In coastal areas, which are often hit by typhoons, traditional streetlights may be damaged by wind and flooding, but solar streetlights, with their sturdy structure and good waterproof performance, are able to maintain stable operation in inclement weather, ensuring the reliability of lighting.
(4) Intelligent Technology
Many solar street lights are equipped with advanced sensors and intelligent control systems. The light control sensor can automatically switch on and off the light according to the change of the ambient light without human intervention. Human infrared sensors can sense whether there are people around, when someone is close, the street lamp automatically increases the brightness, providing sufficient lighting for pedestrians; no one, the street lamp automatically reduces the brightness or extinguished, thus realising the perfect combination of energy saving and efficient lighting. Some high-end solar street lamps also have remote monitoring function, managers can monitor the working status of street lamps in real time through mobile phone APP or computer, such as power, light intensity, fault information, etc., to find and solve the problem in time, which greatly improves the management efficiency.
How does a solar street lights work?
(1) Solar Panel
Solar panel is one of the core components of solar street light, its main role is to convert solar energy into electricity. The common solar panels on the market today are monocrystalline silicon, polycrystalline silicon and amorphous silicon three types. Monocrystalline silicon solar panels have the highest conversion efficiency, up to 20% - 25%, but their cost is relatively high; polycrystalline silicon solar panels have a conversion efficiency of 15% - 20%, the cost is more moderate, the most widely used; amorphous silicon solar panels have a lower conversion efficiency, generally below 10%, but has a thin and lightweight, can be bent and so on, suitable for some special scenarios. During the day, when the sun shines on the solar panels, photons interact with the semiconductor materials in the solar panels to produce electron - hole pairs, and these electrons and holes move directionally under the action of the electric field to form an electric current.
(2) Battery
The DC current generated by the solar panel is transported to the battery for storage. Currently, the batteries commonly used in solar street lights are lead-acid batteries, colloidal batteries and lithium batteries. Lead-acid battery price is low, mature technology, but the energy density is low, the weight is big, the life span is short, the general charging and discharging times in the 300 - 500 times or so; colloidal batteries are improved on the basis of lead-acid batteries, the electrolyte is colloidal, has the advantages of sealing good, maintenance-free, long life, etc., the number of times of charging and discharging up to 500 - 800 times; lithium batteries have high energy density, light weight, long life, fast charging speed and other advantages, charging speed and other advantages. Lithium batteries have the advantages of high energy density, light weight, long service life, fast charging speed and so on, and the number of times of charging and discharging can be up to more than 1000 - 2000 times, but the cost is relatively high. When choosing batteries, it is necessary to consider the use of street lamps, lighting needs and costs and other factors.
(3) LED lights
When night falls, the electricity in the battery is released to drive the LED lamps to emit light. LED lamps are solid-state semiconductor devices that can directly convert electrical energy into light energy. Compared to traditional incandescent and fluorescent lamps, LED lamps have a number of significant advantages. First of all, the LED light-emitting efficiency is high, generally up to 100 - 200 lumens / watt, while the incandescent lamp is only 10 - 20 lumens / watt, fluorescent lamps for 50 - 80 lumens / watt; Secondly, the LED lamps have a long lifespan, generally up to 50,000 - 100,000 hours, incandescent lamps 50 - 100 times, fluorescent lamps 5 - 10 times; In addition, the LED lamps have a fast response time, In addition, LED lights also have a fast response time, good colour rendering, energy saving and environmental protection, etc., can provide people with more comfortable, bright lighting environment.
(4) Controller
Controller is one of the core components of the solar street light system, it is like a commander, responsible for managing the operation of the entire system. The main functions of the controller include controlling the charging process of the solar panel on the battery, preventing the battery from overcharging or over-discharging, and prolonging the service life of the battery; automatically controlling the switching and brightness adjustment of the street light according to the changes of the ambient light and the signals from the sensors; and monitoring the system's working status, such as the battery charge level, the output voltage and current of the solar panel, etc., and alarming the system in time in the event of a malfunction. Currently, there are two types of controllers on the market: PWM (Pulse Width Modulation) controllers and MPPT (Maximum Power Point Tracking) controllers.MPPT controllers are able to track the maximum power point of solar panels in real time to improve the efficiency of solar energy utilisation, and can generate 10% - 30% more power than PWM controllers.
How Long Does a Solar Street Light Work?
(1) Life of each component
The service life of solar street light mainly depends on the service life of each component. Generally speaking, the service life of solar panel can reach 25 - 30 years, but its conversion efficiency will gradually decrease with the passage of time. For example, a new solar panel with an initial conversion efficiency of 20% may drop to about 18% after 10 years of use, and to about 15% after 20 years of use.LED lamps have a very long lifespan of 50,000 - 100,000 hours, which means that they hardly need to be replaced under normal use. However, the life of an LED lamp can be affected by poor heat dissipation or unstable operating voltage. Battery life is relatively short, generally 3 - 7 years, depending on the type of battery, the use of the environment and the number of times of charging and discharging. Such as lead-acid batteries in frequent charging and discharging and high-temperature environment, the life of the battery may only be about 3 years; while lithium batteries in the case of reasonable use, the life of up to 5 - 7 years. Controller life is generally about 5 - 10 years, its life is mainly affected by the quality of electronic components and the working environment.
(2) Maintenance and life extension
In order to ensure the long-term stable operation of solar street lights, regular maintenance is essential. Maintenance work includes cleaning the dust and debris on the surface of solar panels to improve their light-gathering efficiency. Research shows that for every 1mm of dust accumulated on the surface of the solar panel, its power generation efficiency will be reduced by about 5% - 10%. Therefore, it is recommended that solar panels be cleaned every 1 - 2 months. Checking the power level and health of the batteries and replacing aged batteries in a timely manner are also important maintenance tasks. For lead-acid batteries, it is necessary to check the level and specific gravity of the electrolyte regularly and replenish distilled water in time; for lithium batteries, it is necessary to avoid over-charging and over-discharging, and carry out deep charging and discharging regularly. In addition, it is also necessary to check the working status of LED lights and controllers to ensure their normal operation. Through reasonable maintenance and repair, it can effectively extend the service life of solar street lights and reduce the cost of use.
Application Scenarios of Solar Street Lights
(1) City Roads
On urban roads, the advantages of solar street lights are especially obvious. Its rapid installation features, without large-scale wiring and excavation works, greatly reducing the impact on traffic. Take a city's main road reconstruction as an example, in the installation of traditional street lights, the need to close the road for cable laying, the construction cycle of up to 3 months, the traffic caused great congestion; and in another road installation of solar street lights, the use of integrated design, no wiring, only 1 month to complete the installation, and the construction process of the impact on the traffic is minimal. Moreover, the zero energy cost operation mode saves the city a lot of electricity expenses. According to statistics, the city spends tens of millions of yuan on street light electricity every year, and if all the street lights are replaced with solar street lights, the electricity bill can be saved by about 80% every year. In some major cities on the main roads and secondary roads, solar street lights have become a bright landscape, not only light up the road, but also for the green development of the city to add a force.
(2) Remote villages
For remote villages, the emergence of solar street lamps has solved the long-standing lighting problems. As these areas are often far from the power grid, the installation cost of traditional street lights is extremely high, and the power supply is unstable. For example, in some remote villages in the west of China, to lay grid lines to the village, the cost per kilometre up to tens of thousands of yuan, and due to the complexity of the terrain, the construction is difficult. The solar street light, with its independent energy supply system, does not need to rely on the power grid, as long as there is sunlight, it can bring light to the village at night. It not only facilitates the villagers' night travelling, but also promotes the economic development and cultural exchanges in the villages. After the installation of solar street lights in some villages, the number of night fairs and cultural activities has increased, enriching the spiritual life of villagers.
(3) Highways
Highways have special lighting needs, and the installation and maintenance costs of traditional streetlights are high. Solar street lights, on the other hand, have become the ideal choice for highway lighting with their convenient installation and stable lighting effect. They are arranged along both sides of the motorway, providing clear lighting for passing vehicles and guaranteeing driving safety. For example, after installing solar street lights on a certain motorway, the incidence of traffic accidents at night has been reduced by about 30%. Moreover, the intelligent control system of the solar street light can automatically adjust the brightness according to the traffic flow and light changes, which further improves the efficiency of energy utilisation. In times of low traffic flow, the street light automatically reduces its brightness to save energy; in times of high traffic flow or bad weather conditions, the street light automatically increases its brightness to ensure driving safety.
(4) Car parks and commercial areas
In car parks and commercial areas, the application of solar street lights can not only meet the demand for high-brightness lighting, but also effectively control costs. Traditional street lamps in these areas have higher operating costs, while solar street lamps have zero electricity costs and low maintenance cost advantages. Take the car park of a large shopping centre as an example, if traditional street lights are used, the annual electricity and maintenance costs can be as high as hundreds of thousands of yuan; while the use of solar street lights, only a small amount of maintenance costs need to be paid annually, about 1/5 of the traditional street lights. in addition, the solar street lights can be combined with the intelligent parking system to achieve a more intelligent management. When the vehicle enters the car park, the street light is automatically lit to guide the vehicle parking; when the vehicle leaves, the street light is automatically extinguished. In some large shopping centres and car parks, solar street lights have become standard, providing a comfortable and safe lighting environment for businesses and customers.
(5) Parks and Scenic Spots
Parks and scenic spots are good places for people's leisure and entertainment, and the installation of solar street lights adds a romantic and warmth to these places. They not only provide safe lighting for visitors, but also design a variety of shapes according to different landscape needs, blending with the surrounding natural environment to create a unique atmosphere. For example, in a famous scenic spot, solar street lights with antique modelling are installed, which complement the ancient architecture of the scenic spot and attract more tourists to visit. At night, the solar street light illuminates the paths of the park and the scenic spots, so that tourists can enjoy the beauty of the scenery at the same time, feel a sense of tranquility and comfort. Moreover, the intelligent control system of solar street lights can also adjust the brightness and colour of the lights according to different time periods and visitor flows, bringing visitors a richer experience.
(6) Disaster-prone areas
In disaster-prone areas such as earthquakes and floods, the power grid is often easily damaged, resulting in power outages. The solar street light, as an independent energy system, is not affected by the power grid and can continue to provide lighting at the moment of disaster. For example, in a certain earthquake disaster, the power grid in the disaster area was all paralysed, and traditional street lights could not be used, but solar street lights still worked normally, providing lighting for the rescue teams and facilitating the rescue work. In some areas that have experienced natural disasters, solar streetlights have become an important part of the reconstruction infrastructure, providing strong support for the recovery and development of the affected areas. They not only provide the affected people with the convenience of life, but also give them comfort and hope psychologically.
With its unique advantages and wide range of application scenarios, solar-powered street light has become an important development direction in the field of modern lighting. Whether it is in the prosperous city, or in the remote countryside; whether it is on the highway, or in the park scenic spots, solar street lights are silently playing a role in bringing light and convenience to our lives. With the continuous progress of technology and further cost reduction, I believe that solar street lights will be used in more areas, to build a greener, low-carbon, sustainable future to make greater contributions. Let's look forward to the solar street lights in the future development to create more miracles, lighting up every corner of our lives.
