In the field of outdoor lighting, human body sensor (PIR) solar lights have become a popular choice for yard, road, parking lot and other scenarios by virtue of the advantages of “no wiring, automatic sensing, energy-saving and environmental protection”. In the field of outdoor lighting, PIR solar lights have become a popular choice for yard, road, parking lot, etc. However, in long-term use, due to the influence of environment and aging parts, the lamps and lanterns may have malfunctioning sensing and not lighting up, etc. In this paper, we will look at PIR solar lamps from the perspective of the human body. In this article, we will start from the working principle of PIR solar lights, analyze the causes of malfunction, list the common problems, and provide step-by-step repair procedures to help you efficiently solve the problems of the light fixtures and restore their normal function.
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To accurately repair a PIR solar light, you first need to understand its core components and the logic of their collaboration — the function of each component directly affects the operation of the light, and when troubleshooting, you will also be able to “The PIR solar light consists of five main components.PIR Solar Lights are made up of five core components, each of which has a function and role as shown in the table below:
| Core Component | Main Function | Impact on Lamp Operation |
| Solar Panel | Captures sunlight and converts it into electrical energy | Directly determines charging efficiency; if shaded or damaged, the battery cannot fully charge |
| Battery | Stores electricity generated by the solar panel during the day and powers the lamp at night | Reduced storage capacity shortens lighting duration or may prevent the lamp from turning on |
| LED Chips | Consume electricity to emit light and provide illumination | Aging or loose connections can cause dimming or complete lighting failure |
| PIR Sensor | Passively detects infrared radiation; triggers the lamp when detecting movement from people or animals | Malfunction may cause the light to fail to turn on or trigger incorrectly |
| Charge Controller | Regulates charging current from the solar panel to the battery, preventing overcharge or overdischarge | Damage can shorten battery lifespan or cause unstable power supply to the lamp |
The PIR sensor is at the heart of the “auto-sensing” function: it does not emit energy itself, but only detects sudden changes in infrared light in the environment. When a heat source, such as a human body (at a temperature of around 37°C), enters the detection range, the sensor recognizes the temperature difference and triggers the light to come on; when the heat source leaves, the light goes off automatically according to a preset time.
PIR solar light failures are not coincidental, and are often related to “environmental effects, power supply issues, and sensor calibration”. Understanding these causes can help you quickly narrow down your investigation.
PIR Solar Lights are exposed to the outdoors for long periods of time. Extreme temperatures, humidity, rain, sunlight, debris and other environmental factors can cause direct damage to components. High temperatures accelerate shell aging and battery degradation, low temperatures reduce battery efficiency or even freeze, but also interfere with the detection of temperature differences in the PIR sensor; poor sealing, rain and dew infiltration will cause circuit board short circuits, terminal corrosion; solar panels anti-reflective film aging, leaves and dust are blocking the sunlight or blocking infrared detection, coastal, rainy and other regions of the lamps and lanterns will be more rapid loss.
PIR sensors and LED beads rely on a stable power supply, and a failure of the power supply system can cause the lamps to fail. Commonly used lithium batteries, lead-acid battery life is usually 2-3 years, aging power storage capacity plummeted, resulting in daytime charging is not enough, can not run at night; charge controller damage will cause the battery over-charging bulging or over-discharge failure, and then let the sensor power outage to stop working; solar panels, batteries and controllers between the wiring if loose or corrosion, will disconnect the circuit, so that the lamps and lanterns are in a “blackout state “.
The modern PIR solar light sensor supports sensitivity, detection range, and light-up duration adjustment, improper setting or not calibrated will trigger abnormal function. If the sensitivity is too high, the wind blowing leaves, small insects flying by, sudden temperature change will trigger the light by mistake, wasting power; sensitivity is too low will lead to sensing failure, the human body close to the light does not light up or need to be triggered by the very close distance; if there are new obstacles around the light or seasonal changes, the sensor detection range will be interfered with the sensor, can not work properly.
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The first type is that the solar light does not light up at all (blackout), there is no sign of charging during the daytime, and it does not light up at night no matter whether there is a heat source close to it or not. The core cause is mostly in the power supply system, which may be a dead battery, disconnected wiring, damaged controller, or burnt out LED beads, resulting in failure to emit light even when the power supply is normal.
The second is the radar induction fault (part of the lamps and lanterns), with the radar module instead of the PIR sensor lamps and lanterns, when the fault is either there is an object moving does not light up, or there is no object when the light is automatically lit up and frequently start and stop. The main reason is that the radar module is damaged, or the detection range is interfered by metal objects such as iron fences and metal billboards, resulting in abnormal signal reception.
The third is that the LED beads do not light up or the brightness decreases, the PIR sensor functions normally, you can hear the triggering sound or see the indicator light with your hand close to it, but the LED beads never light up or the brightness decreases dramatically. The core cause is the aging of the lamp bead to reach the service life, or the lamp bead and the circuit board indirect line loose, false welding, resulting in the current can not be normal through.
The fourth type is frequent starting and stopping of lamps or sudden stopping of work, the lamps go out soon after lighting, start and stop repeatedly when there is no heat source, or suddenly stop all functions. This type of failure is mostly due to improper calibration of the sensor, the sensitivity is too high false triggering or too low resulting in unstable power supply, may also be insufficient battery power, unable to provide stable voltage for the sensor and lamp beads.
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When a luminaire fails, there is no need to directly replace the luminaire with a new one, you can follow the steps below to troubleshoot and repair the problem, and most of the problems can be solved by yourself.
Without disassembling the light fixture, check for non-component damage through appearance and simple operation. Wipe the solar panel with a dry cloth, remove debris and check whether there is cracking and yellowing; make sure the light is installed in an unobstructed area with at least 4-6 hours of direct sunlight per day, and move it in time if it needs to be adjusted; wipe the surface of the PIR sensor and check whether the shell is broken; open the battery compartment to observe whether the battery is bulging and leaking, and if there is a low-battery indicator light, it flashes, which means that it is not enough power.
After the basic check, use two methods to test whether the sensor fails. Manual trigger test without tools, will be placed in a dark environment or black cloth cover solar panels simulate the night, wait 5-10 minutes, with the palm of the hand at 1-3 meters near the sensor, light is normal, not light is tested with a multi meter; multi meter adjusted to the on-off or DC voltage file, disconnect the battery and contact the sensor “VCC, GND “ terminal to measure the power supply, there is voltage and palm close to the ”OUT” terminal changes or beeping, indicating that the sensor is normal, and vice versa is damaged and needs to be replaced.
The sensor is normal but the lamp does not light up, need to check the power supply system. Open the shell to check the wiring, tighten the loose terminals, grinding the rusty parts and apply rust cream, replace the broken wires; use a multi meter to measure the no-load voltage of the battery, lithium batteries less than 3.2V, lead-acid batteries less than 12V need to be recharged, ineffective or the battery leakage leakage of the battery bulging packs will be replaced with the same type; solar panels during the day to align the sunlight to measure the voltage at the input side of the controller, less than the solar panels rated value is the controller may be damaged, need to change the same specification products. Replacing the PIR Sensor
After confirming that the sensor is damaged, follow the steps to replace it with one that requires simple soldering. Prepare a new sensor compatible with the original sensor model, matching voltage, detection angle and wiring, and at the same time ready soldering iron, solder wire, tin sucker and corresponding screwdriver; screwdriver to open the lamps and lanterns shell, find the sensor where the PCB circuit board, with a soldering iron to heat up the old sensor terminals, remove the suction of solder and remove it, pay attention to do not damage the copper foil; will be the new sensor pins aligned with the soldering point welded firmly, reconnected to the battery Test, if normal, put back into the shell, the gap can be coated with waterproof glue to enhance sealing.
After repairing the PIR solar lamp, do two things to minimize subsequent failures and prolong the life of the lamp. First, regular cleaning and inspection, every 1-2 months to wipe the solar panel and sensor surface, every 3 months to open the shell to check the wiring and batteries, rainy season, after winter should be more focused on checking; Second, timely replacement of wearing parts, battery life before the expiration of the battery (usually 2-3 years) in advance of the replacement of high salt spray, rainy areas every year to change the terminal rust cream, to enhance the ability to resist corrosion.
