Driven by the wave of smart city construction and the concept of low carbon and environmental protection, solar street lights are accelerating towards intelligence. With its unique advantages, solar street light with sensors not only innovates the traditional lighting mode, but also brings new possibilities for city management and life scenarios.
Solar streetlights with sensors integrate a variety of key sensors, each playing a unique role.
Photosensitive Sensor: By accurately detecting the ambient light intensity, the street light can be automatically switched on/off and adjusted in brightness. The triggering threshold is usually adjustable between 5-50 Lux. When there is insufficient sunlight, the street light will be lit in time; when there is sufficient light, it will be switched off automatically to ensure energy saving and high efficiency.
Motion/Human Infrared Sensor: It can keenly detect the movement of pedestrians and vehicles. When detecting the target approaching, the street light quickly increases the brightness, and when the target leaves, it automatically reduces the brightness, which not only ensures safety, but also saves energy. The general detection distance is up to 8-12 metres and the angle is 120°.
Temperature sensor: real-time monitoring of the internal temperature of the lamps and lanterns, effectively preventing overheating damage and optimising battery performance. Its working range is usually -40℃-85℃, and its accuracy can reach ±1℃.
Microwave radar sensor: non-contact detection capability, compared with infrared sensors, penetration is stronger, in the rain and snow and other bad weather is still stable work. The detection distance can be up to 20 metres, supporting multi-target tracking.
Environmental monitoring sensors: can monitor air quality (PM2.5, CO, etc.), humidity, wind speed and other indicators, to provide important data support for urban environmental management, such as real-time detection of PM2.5 concentration in the range of 0-1000μg/m³.
There are limitations of a single sensor, and multi-sensor fusion technology can significantly improve the reliability of the system. For example, through the light-sensitive and radar double trigger switch, can avoid the energy waste caused by light misjudgment or false trigger. A brand of street light adopts ‘photosensitive + infrared + temperature’ three sensors to work together, in the case of insufficient light and detecting someone's movement, the street light is automatically adjusted to 100% brightness; in the case of unoccupied state, the brightness is reduced to 30%, and the energy saving rate is increased by 40%.
Solar led streetlights with sensors can realise dynamic lighting on urban main roads. During peak traffic hours at night, the street light remains fully illuminated; in the early hours of the morning, when traffic decreases, it is automatically adjusted to 30% brightness; and when vehicles or pedestrians are detected passing by, it instantly returns to full illumination. This mode not only saves energy by more than 50%, but also reduces light pollution and improves safety when pedestrians cross the road and other unexpected situations.
microwave radar sensors are installed on the street lights to monitor real-time traffic flow, speed and other data. After these data are connected to the city traffic management platform, it can assist in optimising traffic light timing and achieve congestion warning. For example, a smart road in Shenzhen, with the help of street light sensor data, intersection traffic efficiency by 18%.
In communities and parks, human infrared or microwave sensors play an important role. When residents travel at night, the street light automatically enhances the brightness; in the children's play area, steps and other areas, the brightness is increased from the conventional 150Lux to 300Lux when detecting people's activities; some street lights can also be linked with the park map guide screen, which is automatically lit when triggered by sensors to provide night-time navigation services.
When the sensor detects abnormal movement, such as climbing over the fence, the street light automatically shines brightly, and at the same time triggers the security camera to capture and push the information to the property centre. After the installation of such streetlights in a community, the number of nighttime intrusions was reduced by 72%, greatly improving security.
In rural and remote areas, light and energy supply are unstable. The combination of photosensitive and microwave sensors enables the street light to be lit only when people and vehicles pass by, and to remain slightly bright (5-10 Lux) during normal times. Combined with high-capacity batteries, the street light can meet the lighting demand even if the weather is cloudy and rainy for 10 consecutive days. Although the initial investment increases by 20% compared with traditional solar street light, the energy saving cost can cover the price difference in a 5-year cycle.
monitors rural air quality and climate change in real time by deploying environmental monitoring sensors such as PM2.5, temperature and humidity. These data can be used for agricultural planting decisions, such as early warning of frost; can also be used for public health tips to protect the health of residents.
In highways and tunnels, microwave radar sensors monitor the density of vehicles in real time and dynamically adjust the lighting brightness according to the situation. For example, when the tunnel is congested with vehicles, the street light is fully lit; when there are fewer vehicles, the brightness is reduced to 30%. Combined with reflective guide labels, it effectively enhances traffic safety. After the application of a tunnel, the visual fatigue of drivers was reduced by 25%, and the accident rate decreased by 38%.
In scenic areas and trails, human infrared sensors can trigger the light show effect. When pedestrians pass by, the lights on both sides of the trail change colour with their movement, enhancing the tourists' experience. At the same time, by reasonably adjusting the light intensity, reduce the impact on the ecology of plants and animals at night.
Solar street lights with sensors have outstanding performance in energy saving. Taking urban main roads as an example, the traditional solar street light consumes 0.96kWh per day according to 80W power and 12 hours of work per day; the average power of the street light with sensors is 40W and the daily energy consumption is 0.48kWh, with an energy-saving rate of 50%, and the 100 street lights can save about 21,900 yuan in electricity costs per year. In the community road scenario, the energy saving rate can reach 58%, and the annual electricity cost can be saved about 13,140 RMB.
These streetlights are not only lighting devices, but also data collection nodes. Municipalities can use the streetlight sensor network to build a city lighting and environmental database to support smart city decision-making, such as optimising sanitation routes and predicting the spread of diseases. In the commercial field, the human flow data collected by sensors can be used for precise positioning of advertising, pushing commercial advertisements in high-frequency crowd areas to create additional revenue.
There is a compatibility problem with multi-sensors working together, and the protocols of sensors from different vendors may conflict. It is recommended to choose an integration solution that supports standardised interfaces (e.g. Modbus, Zigbee). In areas with harsh environments such as high temperature and humidity, it is necessary to strengthen the protection of sensors by adopting IP68 encapsulation and regularly cleaning dust to ensure that the sensitivity is not affected.
The cost of sensors accounts for about 15%-25% of the initial investment in solar street lights with sensors. The cost can be shared by applying for special subsidies such as the government's New Infrastructure Fund or adopting the contract energy management (EMC) mode. In terms of long-term operation and maintenance, choose lamps with remote monitoring function, real-time feedback sensor status through LoRa/NB-IoT, and reduce the cost of manual inspection.
In the future, solar street lights with sensors will be deeply integrated with AI algorithms. Through the analysis of sensor data, predictive maintenance will be achieved, and passive maintenance will be transformed into active optimisation. For example, Philips CityTouch system, with the help of AI analysis data, maintenance efficiency is increased by 40%.
Streetlights are expected to become ‘urban energy nodes’, and in the future, they will integrate functions such as charging piles and 5G micro-base stations. At the same time, sensor data and energy management in depth synergy, for example, according to the charging load of electric vehicles, intelligent scheduling of street lamp energy supply.
Solar streetlights with sensors have gone beyond the scope of traditional lighting and become an important foundation for smart city construction. It has significant advantages in energy saving, safety, management, etc., and is suitable for new roads, transformation projects and various intelligent demand scenarios.
Municipal project selection, it is recommended to give priority to the ‘photosensitive + microwave radar + environmental monitoring’ combination, taking into account the lighting and data collection; community, park focus on human infrared sensors and security linkage; remote areas to ‘photosensitive + microwave’ as the main, to ensure that the Low energy consumption and high reliability.
