Solar road studs are the core equipment for outdoor road safety protection, widely used in highways, municipal roads, park walkways, airport runways, and other scenarios. They rely on solar energy for autonomous power supply, without the need for external circuits, and are easy to install and have low operation and maintenance costs.
The core working principle is very clear: during the day, the solar panel absorbs natural light and converts it into electrical energy, which is stored in the battery; at night, when there is insufficient light, the battery releases electrical energy to drive the LED light bulbs to emit light, serving as a road warning and guidance for traffic.
In the entire equipment, the solar panel is responsible for energy collection, the LED light is responsible for emitting light display, and the battery is the core heart that determines the overall performance and service life of the equipment. The quality and type of the battery directly control the three core performance indicators.
The first is the battery life, which determines the duration of continuous lighting in the night and in rainy weather; the second is the operational stability, which affects the working state in complex outdoor climates; the third is the life cycle and maintenance cost, which determines the long-term investment budget of the project.
According to industry authoritative statistics, about 60% of the failure problems of solar road studs are caused by battery failure, degradation, or damage. It can be said that choosing the right battery type basically guarantees the long-term stable operation of solar road studs.
Currently, the energy storage batteries suitable for solar road studs on the market are mainly divided into three mainstream types, covering all scenarios from the low-end to the high-end, from short-term engineering to long-term infrastructure in the industry.
| Battery Type | Description | Typical Applications |
| Lithium-ion (Lithium / LiFePO4) | The current mainstream high-end battery technology in the industry. Lithium iron phosphate (LiFePO4) is the most widely used type, offering long lifespan, high efficiency, and excellent reliability. | Suitable for high-standard infrastructure projects and long-term road safety applications. |
| NiMH (Nickel-Metal Hydride) | A mid-range battery solution with strong environmental adaptability and excellent low-temperature performance. | Specifically designed for outdoor road projects in cold-climate regions. |
| Lead-acid (Lead-acid / SLA) | A traditional battery technology with mature manufacturing processes and low initial cost. | Commonly used in short-term temporary road projects and budget-sensitive installations. |
There is no absolute superiority or inferiority among the three batteries; only differences in scene adaptation exist. The core reference dimension for industry selection is: comprehensive cost, service life, climate adaptability, and energy density.
The performance differences in different dimensions directly determine the landing scenarios, operation cycle, and overall project cost performance of solar road studs, and are also the core basis for engineering procurement and project selection.
Lithium batteries are currently the battery type with the best overall performance for solar road studs, with core advantages concentrated in energy storage efficiency, service life, and operational stability.
Firstly, high energy density, with the same storage capacity, lithium batteries have a smaller volume and lighter weight, which can be adapted to miniaturized and integrated solar road studs structures without affecting the installation and compressive performance of the equipment.
Secondly, ultra-long cycle life, standard lithium batteries have a cycle life of over 1500–2500 times, far exceeding the other two batteries, significantly reducing the frequency of equipment replacement.
At the same time, lithium batteries have extremely low self-discharge rate, only 2–3% per month, and the battery’s charge loss is slow in long-term storage, rainy, and scarce sunlight environments, ensuring the equipment remains ready.
In addition, lithium batteries have a stable output voltage, allowing the LED light bulbs to have uniform brightness and no flicker, ensuring stable night-time warning effect and improving road safety.
Among lithium battery categories, lithium iron phosphate (LiFePO4) has completely replaced traditional lithium cobalt oxide batteries and become the exclusive mainstream battery for solar road studs.
Its greatest advantage is extremely high safety, with almost no risk of thermal runaway, resistance to high temperatures, and aging, perfectly adapting to harsh working conditions such as outdoor exposure to sunlight and rain erosion. Compared with other batteries, LiFePO4 is more suitable for long-term 24-hour uninterrupted operation in outdoor environments, with extremely low failure rate and minimal maintenance workload.
Currently, in high-reliability and high-safety infrastructure projects such as highways, airport runways, and national trunk roads, all adopt LiFePO4 battery solar road studs.
Lithium batteries have obvious limitations in low-temperature use. They cannot charge properly in temperatures below 0°C and require a dedicated protection circuit; otherwise, they are prone to battery damage and capacity reduction.
In terms of cost, lithium batteries are more expensive. The overall procurement cost is 30-50% higher than NiMH batteries and is the highest among the three types of batteries in terms of initial investment.
The biggest core highlight of NiMH batteries is their extreme adaptability to low temperatures. They can stably charge and discharge and operate normally at -20°C, without shutdown or capacity degradation.
They have excellent safety performance, with a stable battery structure, no thermal runaway, no risk of explosion or fire, and high safety coefficient for outdoor use, without the need for complex protective devices.
The cost and performance ratio is moderate, and the procurement price is lower than that of lithium batteries. It is an ideal choice for small-budget projects in cold regions that balance performance and cost.
Low energy density is the core weakness of NiMH batteries. Under the same storage capacity, the battery volume and weight are larger, increasing the overall volume of the solar road stud equipment, which is not conducive to miniaturization design.
The self-discharge rate is high, with a monthly self-discharge loss of 15-20%. In long-term cloudy or smoggy weather, the battery capacity loss is fast, and there is a problem of insufficient night-time power supply.
The cycle life is short, only 500-800 cycles, and the equipment replacement cycle is shorter, resulting in gradually increasing long-term operation costs.
Lead-acid batteries are the oldest and most mature energy storage battery technology. It has a complete production process and high market penetration, with almost no technical failure risks.
Its core advantage is extreme low cost, being the lowest among the three types of batteries in terms of procurement price, significantly reducing the initial investment cost of equipment.
In the early stage of the solar road stud industry development, lead-acid batteries were the mainstream standard solution, widely used in various ordinary road lighting and warning projects.
Lead-acid batteries are large in size and heavy, significantly increasing the overall weight of the solar road stud, not only making installation inconvenient but also affecting the design of the equipment’s anti-pressure and waterproof structure.
The deep discharge capacity is extremely poor, frequent deep discharge will directly cause irreversible damage to the battery, and the daily usage fault tolerance is extremely low.
Long-term outdoor use is prone to plate sulfation problems, resulting in rapid capacity reduction and shortened lifespan, and overall short lifespan.
At the same time, the adaptability to high and low temperatures is poor. High temperatures are prone to bulging, and low temperatures are prone to power loss. Under extreme weather conditions, the failure rate is extremely high, and it cannot adapt to long-term outdoor high-standard scenarios.
To facilitate quick selection, we conduct a comprehensive comparison of LiFePO4 batteries, NiMH batteries, and lead-acid batteries from multiple dimensions including core performance, cost, and adaptability. The data is clear and intuitive.
| Comparison Dimension | LiFePO4 Batteries | NiMH Batteries | Lead-Acid Batteries |
| Energy Density | Highest, compact and lightweight | Medium, slightly larger size | Lowest, bulky and heavy |
| Cycle Life | 1,500–2,500+ cycles | 500–800 cycles | 300–500 cycles |
| Monthly Self-Discharge Rate | 2–3% | 15–20% | 10–15% |
| Low-Temperature Performance | Poor (requires protection below 0°C) | Excellent (stable operation at -20°C) | Poor, prone to capacity loss in cold temperatures |
| Initial Procurement Cost | High (30–50% higher than NiMH) | Medium | Low |
| Long-Term Operating Cost | Very low, long service life with minimal failures | Medium, may require replacement during service life | High, frequent replacement and maintenance required |
Highways, airports, long-term infrastructure projects: Prefer LiFePO4 batteries, relying on their long lifespan, high stability, and low maintenance advantages, they are suitable for long-term high-standard operation requirements.
Cold and low-temperature areas (-20°C and below): Prefer NiMH batteries, which can avoid charging failure at low temperatures and ensure the normal operation of equipment in winter.
Short-term temporary projects, low-budget small-scale projects: Prefer lead-acid batteries, relying on their low cost advantage, they can meet short-term usage requirements and control project investment.
Solar road studs work in an open-air environment all the time. Climate conditions are the core external factors affecting battery lifespan and equipment stability. Different climate regions require targeted selection.
In high-temperature environments, lead-acid batteries are prone to bulging and sulfation, while NiMH batteries have a faster capacity decline. However, LiFePO4 batteries have extremely strong thermal stability and can withstand high temperatures and resist aging.
Their extremely low self-discharge rate can adapt to long-term strong sunlight exposure conditions, and their service life is significantly better than the other two types of batteries, reducing the equipment failure rate in high-temperature environments.
LiFePO4 batteries cannot be charged below 0°C. In extreme cold weather, the equipment is prone to power failure and failure. While NiMH batteries can work stably at -20°C and are suitable for extreme cold scenarios.
For some low-cost projects in cold environments, a lead-acid battery system with a heating module can be selected to balance cost and low-temperature working performance.
In rainy and cloudy weather, the charging efficiency of solar panels significantly decreases, and the battery needs to have low self-discharge and high storage efficiency characteristics.
LiFePO4 batteries have a monthly self-discharge rate of only 2%-3%, with extremely strong battery capacity retention, capable of supporting continuous 7-15 days of rainy weather and normal lighting, suitable for southern rainy and coastal foggy weather scenarios.
Apart from battery type, the matching degree of core parameters directly determines the implementation effect of solar road studs. When selecting, it is necessary to focus on checking the following two key parameters.
The mainstream industry-compatible voltages are 3.2V and 12V. They need to be precisely matched with the LED lights of the road studs and the voltage system of the solar panels to avoid overload and power failure damage to the equipment.
Select based on the required duration of project operation. The larger the capacity, the stronger the battery capacity retention in rainy weather, suitable for high-standard road projects.
The standard selection requirement is ≤ 0.5C. Excessive charging current will accelerate battery aging and shorten the equipment service life.
LiFePO4 batteries support deep discharge up to 80% or more. NiMH and lead-acid batteries are prone to damage the cells when deeply discharged. The selection must match the discharge requirements.
Preferentially choose batteries with high cycle count. For long-term projects, it is recommended to be above 1500 cycles; for short-term projects, a specification of around 500 cycles can be adapted.
Based on the local climate of the project, select battery models that are compatible with the extreme temperature limits to avoid climate compatibility failures.
The core reason is that it has the best overall performance, featuring three core advantages: extremely long cycle life, high safety stability, and extremely low self-discharge rate. At the same time, the operation and maintenance cost is extremely low, and there is no need for frequent replacement. It is suitable for the vast majority of outdoor long-term road projects, and the cost performance throughout the entire life cycle far exceeds NiMH and lead-acid batteries.
Not yet. NiMH battery has an irreplaceable advantage in low-temperature scenarios. In small and medium-sized road projects in northern cold and high-altitude areas, it is still the core selection scheme for solar road infrastructure, specifically compensating for the short-term failure of lithium batteries in low temperatures.
It has extremely high short-term use value. The initial procurement cost of lead-acid battery solar road infrastructure is the lowest. For temporary road construction, short-term lighting projects, and low-budget rural road projects with low budgets, it can meet the short-term usage needs and has a highly precise cost performance.
LiFePO4 battery has the longest service life. The standard cycle life can reach more than 1500–2500 times, which is 3-4 times that of NiMH batteries and about 5 times that of lead-acid batteries. The long-term usage advantage is extremely prominent.
The battery is the core heart of the solar road road stud, determining the stability, endurance, lifespan and overall usage cost of the equipment. It is a crucial aspect that cannot be ignored in the project selection process.
Looking at the industry trend, the battery selection for solar road road studs has undergone iterative upgrades. The overall evolution path is: lead-acid battery → NiMH battery → LiFePO4 battery.
However, there is no universal battery model. The optimal selection requires a comprehensive judgment based on three core factors: the climate conditions of the project location, the project usage period, and the overall project budget.
For long-term high-standard infrastructure projects, LiFePO4 batteries are preferred. In cold regions, NiMH batteries are suitable. For short-term projects with a low budget, lead-acid batteries can be selected. Precise selection can maximize both cost-effectiveness and stability.
