In high-altitude and cold regions, the road maintenance departments encounter common problems every winter: solar road studs that were operating stably and brightly in summer start to frequently malfunction in winter. The most common manifestations are a significant reduction in the duration of light emission and a noticeable decline in light brightness. In severe cases, the entire solar road stud completely stops working. When disassembled, it can be found that water has entered the equipment and components have frozen.
Most people would simply attribute the failure to "insufficient solar panel power generation in winter". However, the actual situation is more complex. The failure of solar road studs in winter is basically caused by a coordinated failure of the battery storage, charging system, and sealing protection in the core components. Understanding the core mechanism of the failure of solar road studs in winter not only enables precise fault detection but also helps road engineering procurement and maintenance personnel avoid inferior products and select high-quality solar road studs that can withstand harsh cold environments.
The battery is the core energy storage component of solar road studs and the most prone to problems in winter. The discharge performance of all mainstream road stud batteries in low-temperature environments will show varying degrees of degradation, which is the fundamental reason for the reduction in the battery's range in winter.
The low-temperature tolerance of different types of batteries varies significantly. The following are industry-standard low-temperature test data (-20°C environment), clearly comparing the winter performance of various batteries:
|
Battery Type |
-20°C Available Capacity (Relative to Normal Temperature) |
Core Characteristics of Low-Temperature Performance |
|
Lead-Acid Battery (AGM/GEL) |
50%–60% |
Experiences the most severe low-temperature degradation. Internal resistance increases sharply, while discharge capacity decreases significantly. |
|
Nickel-Metal-Hydride Battery (Ni-MH) |
70%–80% |
Offers the best low-temperature performance and is a mainstream battery choice for solar road studs used in cold regions. |
|
Lithium Iron Phosphate (LiFePO4) |
60%–75% (discharge state) |
Provides acceptable low-temperature discharge performance, but charging is severely restricted at low temperatures and requires a current-limiting protection circuit. |
Note: These are industry-standard test ranges, and actual performance is affected by factors such as cell manufacturing quality and has some fluctuations.
This set of data clearly shows the winter range dilemma of the road studs: A road stud that can fully charge for 10 hours at normal temperature will only have 6-7 hours of effective power in -20°C severe cold conditions.
Adding the problem of insufficient winter sunlight, the battery will remain in a "not fully charged, consumed quickly" state of depletion. Within just a few weeks, it will fall into a deep depletion state, causing irreversible damage to the battery. The industry often says "winter road studs starve, not freeze", which is precisely this principle.
Here is a correction of a common misconception: LED light beads themselves are adapted to low-temperature environments. The lower the junction temperature of semiconductor light beads, the higher the light emission efficiency. Therefore, the brightness of the road studs in winter is insufficient and has nothing to do with LEDs, the problem is entirely in the battery storage and charging system.
Many people mistakenly believe that low temperature will reduce the power generation efficiency of solar panels. In fact, the opposite is true. According to the public data of the US Department of Energy, the optimal working temperature for solar panels is 25°C. The higher the temperature, the lower the power generation efficiency. The power generation efficiency of solar panels in low-temperature environments is actually higher.
The core problem of charging for winter road studs is not "not generating electricity", but "not charging fully", mainly affected by three natural factors:
In high-altitude regions during winter, the day is short and the night is long, the effective sunlight duration is only half of that in summer, and the time for solar panels to generate electricity is significantly compressed.
In winter, the sun's rays are oblique, and the light cannot be vertically irradiated on the solar panel surface. The same area of solar panels receives significantly less light energy, and the daily electricity generation is significantly reduced.
During winter, there are frequent occurrences of cloudy days, snowfall, and smog. When snow covers the photovoltaic panels, it can cause the studs to generate almost no electricity for several consecutive days.
After the combination of these three factors, the single-day charging capacity of solar powered road studs in winter is only 30% - 40% of that in summer. If the product does not have a high-quality MPPT charging management system or does not have a low-temperature current-limiting design, the battery will remain in a semi-depleted state for a long time, eventually resulting in a failure such as "the light-on time getting shorter day by day".
Industry warning: Studded products that only indicate "full battery endurance time" but do not indicate "number of consecutive snowy days for operation" have no guarantee of reliability in the harsh winter environment.
Compared to batteries and charging issues, sealing failure is the most concealed and has the highest rework rate for winter studded faults. Many studded products that passed the IP68 static waterproof test completely break down after 1-2 years of use in winter, the core problem being that they cannot withstand the freeze-thaw cycles in winter. The aging and failure process of winter studded sealing has a fixed pattern and is a typical chronic damage:
The temperature difference between day and night in winter is extremely large. During the day, the studded is baked by the high-temperature road surface, and the internal air expands; at night, the low temperature cools it down, and the internal air contracts. The repeated expansion and contraction cycle will act like a pump, sucking in external water vapor and moisture into the equipment shell.
Common sealing rings and encapsulation adhesives have poor low-temperature resistance and will quickly harden and lose elasticity in extremely cold environments below -20°C. The originally tiny sealing gap is enlarged, and the waterproof protection barrier completely fails.
The water vapor that seeps into the shell freezes when it gets cold, and the volume will expand by about 9%. A single freeze-thaw cycle may crack the studded shell, break the internal circuit board, and cause permanent damage.
This is also the limitation of the IP68 waterproof test: the static water immersion test in the laboratory cannot simulate the real temperature difference cycles and freeze-thaw impacts in the outdoor environment. High-quality cold-resistant studded products will use low-temperature polyurethane encapsulation adhesives and cold-resistant sealing rings to avoid freeze-thaw damage from the material level.
In snowy areas, the physical impact from snow removal operations is an important external force factor for the damage of solar studded products. The protruding installation form of the studded on the road surface makes it highly susceptible to continuous impact from snow removal equipment and ice-mixed substances.
During snow removal operations, the scraper will directly scrape and hit the road surface studded, causing the shell to deform, the fixation to loosen, and the studded to shift or fall off.
The snow-melting agent sprayed during snow removal operations and the high-speed flying ice-mixed substances will continuously wear down the protective structure on the surface of the studded, gradually thinning the sealing layer and accelerating water ingress failure.
studded shell made of ordinary PC material will become much more brittle in low-temperature environments, with a significant drop in impact and crushing resistance. Once there are minor cracks, they will quickly spread under the impact of vehicle rolling and wind-snow impact, causing permanent damage.
From the installation scenario, the damage rate of studded products in the center of the lane is much higher than that on the shoulder. The core reason is that the main sweeping path of the snow removal equipment is concentrated on the traffic lane, which is also the area that needs to be carefully inspected during winter road maintenance.
Winter is the "trial gold" for testing the quality of solar studded products. Inferior studded products often cannot survive the first winter, and their core defects are concentrated in four dimensions, all caused by cost trade-offs during the production stage:
The actual energy storage capacity of solar studded products is far lower than the nominal parameters, and it further decays at low temperatures, making it prone to rapid depletion and scrapped.
Cheap solar energy road studs lack the design features of low-temperature charging current limiting and discharge protection. In extremely cold environments, charging will accelerate battery wear and cause lithium precipitation and bulging problems.
Using ordinary rubber sealing rings and inferior potting materials, the potting is not fully filled, and the sealing fails at low temperatures, with a very high probability of water ingress and freezing.
Low-quality solar energy road studs use ordinary recycled PC materials, which have severe low-temperature brittleness, and have extremely poor impact resistance and crush resistance, unable to withstand winter snow removal and vehicle crushing.
Industry consensus: In summer, the performance differences of almost all solar energy road studs are minimal. Only in winter can the quality of products be truly distinguished. The winter stability of the road studs directly represents the true quality of the product.
For already installed road road studs, conduct systematic inspection and maintenance before winter sets in, which can significantly reduce the failure rate in winter and extend the service life of the equipment. For newly purchased products, special parameter verification can be used to avoid inferior products.
Conduct random checks on the brightness of the lights and battery endurance of road studs in different sections, record basic data, and facilitate subsequent comparison of fault issues.
Focus on key points such as curves, ramps, and unlit sections, as the failure of road studs in these areas will directly affect driving safety, and are the focus of maintenance.
Complete special inspections within 24 hours after each heavy snowfall or snow removal operation, check the integrity of the shell, the firmness of anchoring, and promptly repair loose or damaged equipment.
Prioritize referring to the "continuous snowy days continuous operation time" parameter. This parameter can more accurately reflect the winter working performance of the road studs than the conventional "full battery endurance time".
Require solar energy road stud suppliers to provide complete low-temperature test reports, with a focus on verifying three core indicators:
Battery low-temperature capacity retention rate, low-temperature charging protection function, and temperature difference cycle sealing test report
Refuse to rely solely on the static waterproof report of IP68 as the protection basis
Pay attention to the freeze-thaw cycle and temperature difference aging test data of the product.
The winter failures of solar energy road studs almost never have uncontrollable factors. All failure problems arise from the cost trade-offs made by manufacturers in battery selection, charging system design, sealing process, and raw material quality.
High-quality road studs that can stably withstand three or more winters have a very small cost gap with inferior road studs, but the reliability of winter operation and service life differ significantly.
For engineering procurement and road maintenance parties, there is no need to worry about conventional endurance parameters. Focus on the two core indicators: the number of days the road studs can work in continuous snowy days and the low-temperature battery capacity retention rate at -20℃, to accurately judge the winter cold resistance reliability of the road studs.
Not necessarily. Most of the problems such as battery capacity reduction and shortened battery life in winter are caused by low temperatures, which lead to battery capacity degradation and insufficient charging, resulting in a temporary deep discharge. These are recoverable states. However, if the battery remains in a depleted state for a long time, it will cause irreversible damage to the battery and eventually lead to its complete failure.
LiFePO4 batteries have a long lifespan and high safety at high temperatures, but they have a significant weakness in low-temperature performance. The discharge capacity drops significantly at low temperatures, and they cannot be charged at low temperatures. Using this battery in extremely cold regions requires a dedicated low-temperature protection circuit; otherwise, problems such as lithium leaching and battery failure may occur.
Yes. IP68 is only a laboratory static water immersion waterproof certification and cannot simulate the outdoor temperature differences between day and night and freeze-thaw cycles. The breathing effect in winter will continuously pump water vapor into the housing. When the water vapor freezes and expands, it will directly cause damage inside the equipment.
No. The power generation characteristics of photovoltaic modules are "high efficiency at low temperatures and low efficiency at high temperatures". The low-temperature environment in winter is actually conducive to improving power generation efficiency. The core reason for the insufficient charging of the road studs in winter is the short duration of sunlight, low solar altitude angle, and rain and snow weather blocking, rather than the decline in the efficiency of the photovoltaic panels.
