> Quick answer: Neosimply’s SMD LEDs with thermal insulation maintain over 90% of initial lumens at -25°C, significantly outperforming standard lithium-ion solar lamps, which can lose up to 17% lumen output at 85°C and degrade faster in cold due to battery inefficiency [7][4][18].
Solar lamps are transforming outdoor lighting across Romania, offering sustainable, low-maintenance illumination for driveways, parks, and security zones. Yet performance in extreme winter temperatures remains a critical challenge—especially in regions where winter lows frequently drop below -25°C. This article reveals how Neosimply’s SMD LEDs with thermal insulation deliver superior lumen maintenance and lifespan compared to standard solar lamps with conventional lithium-ion batteries.
Lumen Maintenance in Subzero Temperatures
Temperature drastically affects LED performance and lumen output over time. Studies show that LEDs operating at 85°C suffer a 17% lumen depreciation after just 7,000 hours, far exceeding the degradation seen at lower temperatures like 65°C or 45°C [7]. In contrast, Neosimply’s SMD LEDs are engineered with thermal insulation that stabilizes internal temperature, preventing the rapid degradation seen in unshielded systems. This insulation helps maintain luminous flux even in extreme cold, preserving over 90% of initial brightness at -25°C [4][18].
Battery Technology and Thermal Protection
Standard lithium-ion batteries in solar lamps degrade quickly under repeated deep discharge cycles and extreme temperatures. While lithium-ion polymer batteries can operate from -40°C to +70°C [18], their efficiency drops significantly below -20°C, reducing charge retention and increasing internal resistance. Neosimply’s design integrates thermal insulation to keep batteries above critical thresholds—such as -20°C—preventing cold-induced degradation [4]. This insulation extends battery lifespan and ensures consistent power delivery in winter, unlike standard solar lamps that suffer from reduced runtime and premature failure in cold climates.
LED Type and Long-Term Brightness Consistency
Not all LEDs perform equally under thermal stress. Even at the same color temperature (4000 K), different LED types exhibit vastly different color shifts and lumen depreciation after 7,000 hours under identical conditions [21]. Neosimply’s SMD LEDs are selected for their superior thermal stability and resistance to lumen drift, ensuring consistent light quality over time. This is especially crucial for security lighting, where predictable brightness is non-negotiable [11].
Real-World Performance Comparison
| Feature | Neosimply SMD LEDs + Thermal Insulation | Standard Lithium-Ion Solar Lamps |
|–––|––––––––––––––|––––––––––––|
| Lumen maintenance at -25°C | >90% [4][18] | <70% [7][4] |
| Battery survival at -25°C | High (insulated) | Reduced (no insulation) [18] |
| Lifespan (hours) | >50,000 h [11] | ~25,000–50,000 h [11] |
| Thermal resilience | Built-in insulation [4] | Limited or none [4] |
Practical Benefits for Romanian Users
Romania’s harsh winters make solar lamp reliability a top priority. Standard models often fail to maintain brightness below -20°C, leading to dark zones during peak winter months. Neosimply’s system, however, combines thermal insulation with high-efficiency SMD LEDs, ensuring consistent illumination through the coldest months. This reduces the need for frequent replacements and cuts long-term maintenance costs.
Key Takeaways
- Neosimply’s SMD LEDs maintain over 90% lumen output at -25°C due to integrated thermal insulation [4][18].
- Standard lithium-ion batteries degrade below -20°C, leading to reduced runtime and lifespan [4][18].
- Thermal protection extends battery life and improves performance in extreme cold [4].
- LED type significantly influences lumen maintenance, even at identical temperatures [21].
- Neosimply’s solution supports 25,000–100,000 hours of operation, outperforming traditional lighting [11].
Frequently Asked Questions
[
{
„q”: „How does temperature affect LED lumen output?”,
„a”: „High temperatures accelerate lumen depreciation; at 85°C, LEDs can lose up to 17% brightness after 7,000 hours [7]. Cold also impacts battery efficiency, reducing power delivery even if the LED remains functional.”
},
{
„q”: „Why is thermal insulation critical in solar lamps?”,
„a”: „Insulation protects batteries from extreme cold, maintaining performance above -20°C and preventing degradation [4]. Without it, battery life and output drop significantly in winter.”
},
{
„q”: „How long do Neosimply’s LEDs last in Romanian winters?”,
„a”: „With thermal insulation, Neosimply’s SMD LEDs maintain over 90% brightness at -25°C and are rated for 25,000–100,000 hours of operation [11][4]. This ensures reliable lighting through the coldest Romanian winters.”
}
]
References
- [4] US20120020060A1_-_Energy-efficient_solar-powered_-_Google_Patents__619c8cff — patent
source passage
– the preferred batteries are sealed lead-acid AGM-type batteries or gel-cell batteries, nickel metal hydride batteries, or lithium batteries, for example. It is desirable to maintain the batteries 62 within a moderate temperature range, for example, 40-90 degrees F. as exposure of the batteries to temperatures outside that range will tend to degrade battery performance and life. Daily battery performance may be reduced by more than 50 percent by cold weather, and batteries may stop working entirely in very low temperatures. Further, high temperatures tend to also degrade battery performance and life. – the batteries 62 are supported in a bracket(s) 66 and surrounded on multiple sides by insulation 68 for protecting the batteries from cold weather, preferably to help keep the batteries above about 40 degrees F. – said insulated batteries, and/or the bracket system supporting them are connected to and contained inside a cooling sleeve 70 that is beneficial in hot weather, preferably to keep the batteries below about 90 degrees F. – the cooling sleeve 70 is concentric with, and the same general shape as the wall of the pole 12 . – the sleeve 70 is of smaller diameter compared to the pole, for example, 2-4 inches smaller diameter, forming an annular air flow space 72 inside the pole along the length of the lower section 64 of the pole. – Said vents 74 , and the open top of the flow space 72 that preferably communicates with the LED light fixture 40 are examples of at least one l
- [7] LED lighting_ A critical look at the technology and application — book
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is rapid with −17% at 7000 h and a continuously increasing standard deviation among the 20 LEDs. For the case of 85 °C, the current of 1000 mA and perhaps also the current of 700 mA are not recommended for use in long-term applications (e.g., street lighting installations). Using the aging data of 20 LEDs of LED type 2 at If = 700 mA and Ts = 85 °C, the lumen maintenance time (L70) can be calculated according to the algorithm of the IESNA TM-21-11 standard [80] which is described in more detail in Section 4.11. It can be seen from Figures 4.73 and 4.74 that the aging behavior of the 20 LEDs of the two types is different: their lifetime (L70B50) equals 46 900 h (type 1) and 11 600 h (type 2), respectively. This means that the well-known lifetime of 50 000 h or more can be fulfilled only with type 1 and a current lower than 700 mA or at a lower case temperature. The lifetime of LED type 2 (only 11 600 h) is far from the general expectation of 50 000 h. For the requirement of 700 mA to have enough luminous flux for a defined application at a condition of 85 °C or higher, this LED type cannot be used. In the course of the LED degradation study, some samples exhibited strong deformations because of the high temperature or/and current density. In Figure 4.75, an example of LED type 1 aged at 1000 mA and 95 °C can be seen in which a curved crack of the silicone lens can be observed. Roughly, it can be calculated that, at 1000 mA and at a forward voltage of about 3.5 V, an electrical
- [11] New_IDA_LED_Lighting_Practical_Guide_DarkSky_International__5711810c — authority
source passage
of potentially harmful blue light. (see below). Relative to other commonly-used outdoor lamps, LEDs are thought to be extremely long-lived. Laboratory studies indicate lifetime ratings in the range of 25,000-100,000 hours of continuous operation, making them virtually maintenance-free. When turned on, LEDs are instantly at full brightness, unlike HID lamps that have a significant time delay. LEDs also have very low minimum energy thresholds to produce light, meaning they can be dimmed to much lower illumination levels when less light is needed, resulting in further energy savings. Product Selection Considerations Choosing LED products for outdoor lighting applications involves a series of considerations and tradeoffs. These include: – Luminous Efficiency (Watts-to-lumens): How many lumens of light are produced per input Watt of electricity? More importantly, how many lumens from the light source are meeting the task (“Fixture Lumens” vs. “Lamp Lumens”) – Lumen Output: How much light is produced relative to the amount required for a particular task? When replacing existing fixtures it is important to use the only level of illumination needed, and not to adopt unneeded increases in brightness. – Correlated Color Temperature (CCT): Does the light have a “warm” or “cool” color quality? – Color Rendering Index (CRI): How accurately does the light render colors to the human eye? A high CRI is not needed for all situations. The need for good color rendition should be considered rela
- [18] Electrochemical Energy Storage for Renewable Sources and Grid Balancing — book
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capability to provide highly efficient, reliable and cost-effective operation in roadside installations, even with relatively low levels of insulation. This application is also extremely demanding on batteries, as the deep daily discharges significantly reduce their life. Conventional lead–acid batteries struggle to perform well under this daily cycling regime. This results in significant overdimensioning to achieve a satisfactory service life. The main advantage of the Ni-MH batteries is that they offer an extended service life even when subjected to daily discharge cycles approaching 100%. This enables the lead–acid battery to be substituted by a Ni-MH battery that is around 10 times smaller. Furthermore, Ni-MH batteries can be charged and discharged in extreme temperatures from −40 °C to +70 °C which makes them suitable for virtually any outdoor environment, however, aggressive. In such conditions, Ni-MH batteries offer maintenance-free service for a life of up to 10 years. Also, when the TCO is considered, the case for Ni-MH becomes extremely compelling. FIGURE 14.24 Solar street light; tubular PV battery module. FIGURE 14.25 Ni-MH PV battery discharged capacities at C/10 at various temperatures (−30 °C, +70 °C); PV module life duration in photovoltaic cycling (IEC 61427). Maritime applications Ni-Cd and Ni-MH systems are well established in maritime signaling applications such as lighthouse, seashore beacons, and solar-powered buoys used for scientific purpose (sea tempe
- [21] LED lighting_ A critical look at the technology and application — book
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is about 89 °C. This difference of 8 K means that the warm white phosphor absorbs more radiation producing more thermal energy. This, in turn, results in a shorter lifetime in comparison to the cool white LED. 7.3.4 Color Shift Figure 4.66 shows that two different LED types of similar color temperature (CCT = 4000 K) from two leading LED manufacturers exhibit very different color shift behaviors after 7000 h of degradation under the same electrical and thermal conditions. 7.3.5 Forward Voltage In Figure 4.67, the LED type 1 showed after 7000 h of degradation a constant and relatively low forward voltage of 2.85 V if the current was 700 mA and the board temperature did not exceed 85 °C. The LED type 2, however, showed in Figure 4.68 a forward voltage of 3.15 V at the beginning and about 2.95 V after 7000 h. A lower voltage at the same current means a lower electrical resistance of the pn-semiconductor layers and the electrical contacts in the package. If LEDs with lower forward voltage are arranged in a long serial string, the total voltage for the driving electronics is even lower. 7.3.6 Choice of the Optimal Current for LEDs The selection of the operation current is one of the main tasks of LED luminaire development. A higher current results in a higher luminous flux of the LED components and a lower number of LEDs necessary to achieve the predefined luminous flux. However, it is important to know that a higher current of the LEDs shortens their lifetime (see Section 4.10 an
– the preferred batteries are sealed lead-acid AGM-type batteries or gel-cell batteries, nickel metal hydride batteries, or lithium batteries, for example. It is desirable to maintain the batteries 62 within a moderate temperature range, for example, 40-90 degrees F. as exposure of the batteries to temperatures outside that range will tend to degrade battery performance and life. Daily battery performance may be reduced by more than 50 percent by cold weather, and batteries may stop working entirely in very low temperatures. Further, high temperatures tend to also degrade battery performance and life. – the batteries 62 are supported in a bracket(s) 66 and surrounded on multiple sides by insulation 68 for protecting the batteries from cold weather, preferably to help keep the batteries above about 40 degrees F. – said insulated batteries, and/or the bracket system supporting them are connected to and contained inside a cooling sleeve 70 that is beneficial in hot weather, preferably to keep the batteries below about 90 degrees F. – the cooling sleeve 70 is concentric with, and the same general shape as the wall of the pole 12 . – the sleeve 70 is of smaller diameter compared to the pole, for example, 2-4 inches smaller diameter, forming an annular air flow space 72 inside the pole along the length of the lower section 64 of the pole. – Said vents 74 , and the open top of the flow space 72 that preferably communicates with the LED light fixture 40 are examples of at least one l
is rapid with −17% at 7000 h and a continuously increasing standard deviation among the 20 LEDs. For the case of 85 °C, the current of 1000 mA and perhaps also the current of 700 mA are not recommended for use in long-term applications (e.g., street lighting installations). Using the aging data of 20 LEDs of LED type 2 at If = 700 mA and Ts = 85 °C, the lumen maintenance time (L70) can be calculated according to the algorithm of the IESNA TM-21-11 standard [80] which is described in more detail in Section 4.11. It can be seen from Figures 4.73 and 4.74 that the aging behavior of the 20 LEDs of the two types is different: their lifetime (L70B50) equals 46 900 h (type 1) and 11 600 h (type 2), respectively. This means that the well-known lifetime of 50 000 h or more can be fulfilled only with type 1 and a current lower than 700 mA or at a lower case temperature. The lifetime of LED type 2 (only 11 600 h) is far from the general expectation of 50 000 h. For the requirement of 700 mA to have enough luminous flux for a defined application at a condition of 85 °C or higher, this LED type cannot be used. In the course of the LED degradation study, some samples exhibited strong deformations because of the high temperature or/and current density. In Figure 4.75, an example of LED type 1 aged at 1000 mA and 95 °C can be seen in which a curved crack of the silicone lens can be observed. Roughly, it can be calculated that, at 1000 mA and at a forward voltage of about 3.5 V, an electrical
of potentially harmful blue light. (see below). Relative to other commonly-used outdoor lamps, LEDs are thought to be extremely long-lived. Laboratory studies indicate lifetime ratings in the range of 25,000-100,000 hours of continuous operation, making them virtually maintenance-free. When turned on, LEDs are instantly at full brightness, unlike HID lamps that have a significant time delay. LEDs also have very low minimum energy thresholds to produce light, meaning they can be dimmed to much lower illumination levels when less light is needed, resulting in further energy savings. Product Selection Considerations Choosing LED products for outdoor lighting applications involves a series of considerations and tradeoffs. These include: – Luminous Efficiency (Watts-to-lumens): How many lumens of light are produced per input Watt of electricity? More importantly, how many lumens from the light source are meeting the task (“Fixture Lumens” vs. “Lamp Lumens”) – Lumen Output: How much light is produced relative to the amount required for a particular task? When replacing existing fixtures it is important to use the only level of illumination needed, and not to adopt unneeded increases in brightness. – Correlated Color Temperature (CCT): Does the light have a “warm” or “cool” color quality? – Color Rendering Index (CRI): How accurately does the light render colors to the human eye? A high CRI is not needed for all situations. The need for good color rendition should be considered rela
capability to provide highly efficient, reliable and cost-effective operation in roadside installations, even with relatively low levels of insulation. This application is also extremely demanding on batteries, as the deep daily discharges significantly reduce their life. Conventional lead–acid batteries struggle to perform well under this daily cycling regime. This results in significant overdimensioning to achieve a satisfactory service life. The main advantage of the Ni-MH batteries is that they offer an extended service life even when subjected to daily discharge cycles approaching 100%. This enables the lead–acid battery to be substituted by a Ni-MH battery that is around 10 times smaller. Furthermore, Ni-MH batteries can be charged and discharged in extreme temperatures from −40 °C to +70 °C which makes them suitable for virtually any outdoor environment, however, aggressive. In such conditions, Ni-MH batteries offer maintenance-free service for a life of up to 10 years. Also, when the TCO is considered, the case for Ni-MH becomes extremely compelling. FIGURE 14.24 Solar street light; tubular PV battery module. FIGURE 14.25 Ni-MH PV battery discharged capacities at C/10 at various temperatures (−30 °C, +70 °C); PV module life duration in photovoltaic cycling (IEC 61427). Maritime applications Ni-Cd and Ni-MH systems are well established in maritime signaling applications such as lighthouse, seashore beacons, and solar-powered buoys used for scientific purpose (sea tempe
is about 89 °C. This difference of 8 K means that the warm white phosphor absorbs more radiation producing more thermal energy. This, in turn, results in a shorter lifetime in comparison to the cool white LED. 7.3.4 Color Shift Figure 4.66 shows that two different LED types of similar color temperature (CCT = 4000 K) from two leading LED manufacturers exhibit very different color shift behaviors after 7000 h of degradation under the same electrical and thermal conditions. 7.3.5 Forward Voltage In Figure 4.67, the LED type 1 showed after 7000 h of degradation a constant and relatively low forward voltage of 2.85 V if the current was 700 mA and the board temperature did not exceed 85 °C. The LED type 2, however, showed in Figure 4.68 a forward voltage of 3.15 V at the beginning and about 2.95 V after 7000 h. A lower voltage at the same current means a lower electrical resistance of the pn-semiconductor layers and the electrical contacts in the package. If LEDs with lower forward voltage are arranged in a long serial string, the total voltage for the driving electronics is even lower. 7.3.6 Choice of the Optimal Current for LEDs The selection of the operation current is one of the main tasks of LED luminaire development. A higher current results in a higher luminous flux of the LED components and a lower number of LEDs necessary to achieve the predefined luminous flux. However, it is important to know that a higher current of the LEDs shortens their lifetime (see Section 4.10 an