Lithium Battery Solar Street Lights: Comprehensive Guide 2025

In recent years, the competition in the solar street light market has been extremely fierce. It is also an inevitable trend that lithium battery solar street lights are gradually replacing lead-acid battery solar street lights. Traditional solar street lights mainly rely on lead-acid battery. However, with the continuous development of lithium battery technology, lithium battery solar street lights have now become the mainstream choice due to their long lifespan and low maintenance. Next, NOKIN will provide you with a detailed analysis of the advantages of lithium battery solar street lights from multiple aspects such as types, selection, installation and maintenance, hoping to offer some useful basis for your decision-making on the solar street light project.

Types and Comparisons of Lithium Battery in Solar Street Lights

Common Types of Lithium Battery for Solar Street Lights

At present, the lithium battery applicable to solar street lights mainly fall into three categories:

• LiFePO4 (Lithium iron phosphate) : It features extremely high safety, can withstand high temperatures (-20℃ to 60℃), and has a long cycle life. It is the preferred type for lithium battery solar street lights.
• NMC/NCA (nickel series) : It has a high energy density, but poor high-temperature stability and weak low-temperature performance. It is only suitable for short-distance projects in mild climates.
• Universal Li-ion: It has a relatively low cost, but a short cycle life (about 800 times) and insufficient safety. It is rarely used in outdoor solar street lights.

Comparison of Core Performance of Lithium Battery Types

Performance Dimension	LiFePO₄	NMC / NCA	Universal Li-ion
Safety	★★★★★	★★★★★	★★★
Cycle Life (times)	2000–3000	1200–1800	600–800
Temperature Adaptability	–20℃ to 60℃	0℃ to 45℃	–10℃ to 50℃
Cost ($/Wh)	0.15–0.20	0.12–0.18	0.10–0.15

 

Why is LiFePO4 the top choice for lithium battery solar street lights? Because it can withstand high temperatures and heavy rain in complex outdoor environments and ensure a service life of 5 to 10 years, significantly reducing maintenance frequency, it meets the demand for "long-lasting durability" of solar street lights.

Lithium battery vs. Lead-acid battery:

Lead-acid battery (including AGM, Gel, and Flooded types) were once the mainstream of solar street lights, but there is a significant gap compared with lithium battery. The specific comparison is as follows:

 

Comparison Dimension	LiFePO₄ Lithium Battery	Lead-acid Battery
Cycle Life	2,000–3,000 cycles (5–10 years)	300–500 cycles (3–5 years)
Weight (Same Capacity)	About one-third the weight of lead-acid	About three times heavier than LiFePO₄
Maintenance Requirements	Low maintenance (only regular BMS checks needed)	High maintenance (water refilling, voltage measurement, periodic inspection)
Energy Density (Wh/kg)	120–150 Wh/kg	30–50 Wh/kg
Installation Method	Lightweight; can be mounted on the back of the pole or placed in a compact battery box	Heavy; requires a fixed ground base or large battery compartment

 

In addition, the discharge efficiency of lithium battery in low-temperature environments is 20% to 30% higher than that of lead-acid battery, making them more suitable for solar street light projects in cold regions.

Key Factors Affecting Lifespan & Performance of Lithium Battery Solar Street Lights

The Core Variables Affecting the Lifespan of Lithium battery

The battery life of lithium battery solar street lights is not a fixed value and is mainly affected by the following factors:

• Depth of Discharge (DoD) : The lower the DoD, the longer the lifespan. For instance, the lifespan is approximately 2,500 times at 80% DoD and drops to 1,800 times at 100% DoD.
• Temperature: Long-term temperatures above 60℃ or below -20 ℃ will accelerate battery degradation. It is recommended to control the temperature through the insulation design of the casing.
• Charging rate (C-rate) : The charging rate of solar street lights is usually 0.1C to 0.2C (fully charged in 10 to 20 hours). A rate higher than 0.5C will damage the battery.
• Storage state of charge (SOC) : When stored for a long time, it is best to maintain the SOC at 50% to 60%. Both fully charged and undercharged storage will shorten the lifespan.

BMS: The Core Protector of Lithium Battery Solar Street Lights

BMS is the key to the safety and longevity of lithium battery. In solar street light systems, BMS effectively addresses the safety and performance issues of lithium battery during use through all-round monitoring and precise management. It is an indispensable and important component for ensuring the reliable operation of lithium battery solar street lights.

 

Functional Module	Main Function	Specific Description
Balanced Charging	Extends overall battery life	Balances the voltage of each cell to prevent single-cell overcharging or overdischarging
Abnormal Protection	Ensures safe battery operation	Automatically cuts off power when a single cell exceeds 3.65V (overcharge), falls below 2.5V (overdischarge), or when abnormal overcurrent occurs
Temperature Monitoring	Prevents temperature-related battery damage	Activates cooling protection when temperature exceeds 65℃; limits discharge when temperature falls below –25℃
Fault Alarm	Enables efficient O&M and quick troubleshooting	Provides real-time battery status and fault information through the communication interface for timely maintenance

 

How to Configure Lithium Battery for Solar Street Lights?

Step-by-step Selection Process for Lithium Battery Solar Street Lights

Step 1: Estimate the load of the lights

Load power (Wh/night) = light power (W) × number of hours of lighting per night (h)

Example: 40W LED light × 10 hours/night = 400Wh/night

Step 2: Confirm sunlight exposure and power generation

The daily power generation of solar panels (Wh) = solar panel power (Wp) × local average sunshine hours (h) × 0.8 (system efficiency)

Example: 100Wp solar panel × 4 hours of sunlight × 0.8 = 320 Wh/day

Step 3: Set the standby days

According to the frequency of local rainy and cloudy weather, the backup days are usually set at 3 to 5 days (5 days is recommended in areas with heavy rain and snow) to ensure the normal operation of solar street lights when there is no sunlight.

Step 4: Calculate the battery capacity and voltage

Core formula

Battery capacity (Ah) = (Load power × standby days) ÷ (System voltage × DoD)

(DoD is taken as 80%, that is, 0.8; the commonly used system voltage is 12V/24V/48V, and for high-power lights, a higher voltage is selected.)

Calculation example

Given: 40W light ×10h=400Wh/night, standby for 5 days, system voltage 24V, DoD 0.8

Battery capacity = (400 × 5) ÷ (24 × 0.8) ≈ 104 Ah

For actual selection, it is recommended to reserve a margin of 10% to 20%, and ultimately choose a 120Ah 24V LiFePO4 battery.

Step 5: Select the battery type and BMS specification

• Battery type: LiFePO4 is preferred. It is a must for harsh environments (high/low temperature).
• BMS specification: It should support overcharge/overdischarge/overcurrent/temperature protection, and be equipped with an RS485 communication interface (for remote monitoring).

Precautions for Battery Pack Configuration in Lithium Battery Solar Street Lights

• Series connection: It is used to increase voltage (such as two 12V batteryconnected in series to form 24V). It is necessary to ensure that the capacity and voltage of each battery are consistent to avoid circulating current.
• Parallel connection: It is used to increase capacity (such as two 100Ah batteryconnected in parallel to form a 200Ah battery). batteryof the same brand and batch must be used, and the BMS should support parallel protection.
• Safety margin: In addition to the capacity margin, the cable diameter should be one specification larger than the calculated value to prevent overloading and overheating.

Installation and Maintenance of Lithium Battery Solar Street Lights

Key Points for Installing Lithium Battery Solar Street Lights

Waterproofing and IP rating: The IP rating of the lithium battery box must be ≥IP65. The connection points should be sealed with waterproof rubber rings to prevent rainwater from seeping in.

Ventilation and heat dissipation: The box body should reserve ventilation holes to avoid direct sunlight (a sunshade can be installed), and prevent the battery from deteriorating due to high temperatures.

Wiring specification: The BMS and the controller should be connected with shielded wires to avoid signal interference. The positive and negative terminal connections must be firm to prevent loosening and sparking.

Weight matching: Although lithium battery are lightweight, when they are mounted on the back, it is necessary to check the load-bearing capacity of the bracket (≥2 times the weight of the battery) to prevent them from falling off.

Maintenance Checklist for Lithium Battery Solar Street Lights

Maintenance Cycle	Maintenance Content	Objective
Monthly	Check the appearance of the battery box and the cleanliness of ventilation holes	Ensure there is no physical damage and no dust blockage
Quarterly	Review BMS alarm logs and measure the total voltage of the battery pack	Confirm no fault alarms and ensure the voltage is within the normal range
Every Six Months	Check the tightness of terminal blocks and the waterproof sealing condition	Ensure there is no loosening and no water ingress
Before Winter	Remove snow from the battery box and check the low-temperature protection function	Ensure normal discharge at –20℃

Long-term Storage Tips for Lithium Battery Solar Street Lights

If solar street lights are out of use for a long time (such as project delays), lithium battery need to:

Storage environment: Temperature 0℃ to 25℃, humidity ≤60%, keep away from fire sources;

• SOC control: Charge to 50% - 60% before storage and recharge every 3 months (to 70%).
• Regular inspection: Measure the battery voltage monthly. If it drops below 2.8V per cell, charge it immediately.

Common Fault Troubleshooting for Lithium Battery Solar Street Lights

Fault Phenomenon	Possible Causes	Solution Steps
Insufficient battery life of solar street lights	Battery capacity decline; BMS failure	Measure battery capacity; Check the BMS alarm log
Lithium battery does not charge	Controller malfunction; Solar panel has no output	Measure the voltage of the solar panel; Reset the controller
BMS alarm light remains constantly on	Overcharge / overdischarge; Abnormal temperature	Cut off the power and check the battery voltage; Check for heat dissipation

Safety & Compliance Standards for Lithium Battery Solar Street Lights

Potential Risks & Control Measures for Lithium Battery Solar Street Lights

The main risk of lithium battery solar street lights is thermal runaway (caused by overcharging and short circuits). The prevention and control measures include:

• Design aspect: BMS dual protection (hardware + software), insulation layer added between battery cells, and explosion-proof valve reserved in the box.
• Selection level: Reject inferior lithium batteryand give priority to products that have passed IEC 62133 and UN38.3 certifications;
• Installation level: Avoid direct contact between the battery and the light(the heat generated by the lightwill be conducted to the battery). Insulate the positive and negative terminals with insulating sleeves.

Transportation & Disposal Compliance for Lithium Battery Solar Street Lights

• Transportation: Lithium batteryare classified as dangerous goods and must comply with UN38.3 transportation standards. The packaging should be marked with "Lithium Battery" and "Anti-drop" labels. For international transportation, an MSDS report must be provided.
• Disposal: Random discarding is strictly prohibited. It must be handed over to a qualified recycling enterprise for disposal (for example, in the United States, it must comply with RCRA regulations; in the European Union, it must comply with the WEEE directive). When making a purchase, it is necessary to confirm whether the supplier provides scrap recycling services to reduce environmental risks.

Cost & ROI Analysis of Lithium Battery Solar Street Lights

Cost Composition of Lithium Battery Solar Street Lights

In the total cost of solar street lights, lithium battery account for approximately 25% to 35%. The specific composition is as follows (taking a 100W solar street light as an example) :

 

Cost Item	Proportion	Cost per Set (USD)	Notes
Lithium Battery	30%	180–220	24V 120Ah LiFePO₄
Solar Panel	25%	150–180	120Wp monocrystalline silicon
LED Light	20%	120–150	40W, 120 lm/W
Controller + BMS	15%	90–110	With remote monitoring function
Installation & Auxiliary Materials	10%	~80	Includes brackets, cables, and labor

Lithium Battery vs. Lead-Acid Battery Solar Street Lights: ROI Comparison

Based on a 5-year project cycle, the investment return differences of a single set of solar street lights are as follows:

 

Cost Type	Lithium Battery Solar Street Light	Lead-acid Battery Solar Street Light	Difference (USD)
Initial Cost	600–740	450–550	150–190
Maintenance Cost (5 years)	50–80	200–250	150–170
Replacement Cost (5 years)	0 (no replacement required)	200–250 (battery replacement in year 3)	–200 to –250
Total Cost of Ownership (TCO)	650–820	850–1050	–200 to –230

 

It can be seen that although the initial cost of lithium battery solar street lights is high, the five-year TCO is 200 to 230 US dollars lower than that of lead-acid battery, and it is more economical in the long term.

Procurement & Acceptance Guidelines for Lithium Battery Solar Street Lights

Core Procurement Criteria for Lithium Battery Solar Street Lights

Battery parameters: Confirm capacity (Ah), voltage (V), cycle life (≥2000 times), and temperature range (-20℃ to 60℃);

Certification report: IEC 62133 (Safety), UN38.3 (Transportation), and MSDS (Chemical Safety) reports are required to be provided.

BMS function: It is required to support overcharge/overdischarge/overcurrent/temperature protection, and be equipped with communication interfaces (RS485 or LoRa).

Warranty period: Lithium battery are guaranteed for no less than 5 years, and BMS is guaranteed for no less than 3 years. Suppliers that offer a "capacity attenuation commitment" (attenuation ≤20% within 5 years) will be given priority.

Delivery & Acceptance Key Points for Lithium Battery Solar Street Lights

Visual inspection: The battery box has no deformation or scratches, and the terminal blocks have no oxidation.

Performance test: Discharge with a capacity tester. The actual capacity should be ≥ 95% of the nominal capacity. The BMS self-check has no fault alarm.

Power-on test: Connect the solar panel to the light, simulate charging/discharging, and confirm that the solar street light is working properly.

How to Choose a Reliable Lithium Battery Solar Street Light Supplier?

Give priority to suppliers with over 5 years of experience in lithium battery solar street lights and those providing localized technical support (such as on-site installation guidance), and avoid purchasing "three-no" products.

FAQ About Lithium Battery Solar Street Lights

Can LiFePO4 lithium battery solar street lights really last for 10 years?

Answer: Under good usage conditions (DoD≤80%, temperature -20 ℃ to 60℃, and high-quality BMS protection), the cycle life of LiFePO4 battery can reach 3,000 times, corresponding to a service life of approximately 8 to 10 years. However, if exposed to high temperatures for a long time or overcharged, the lifespan may be shortened to 5 to 6 years.

Can lead-acid battery solar street lights still be used? When to choose lead-acid?

Answer: It can still be used, but is only suitable for "cost-sensitive + short-term projects" (such as temporary lighting for 1 to 3 years). When the project cycle is no more than 3 years, the budget is limited, and the local climate is mild (0℃ to 3℃), lead-acid battery can be a temporary option. However, for long-term projects (≥5 years), it is still recommended to choose lithium battery solar street lights to avoid the additional costs caused by frequent replacements.

Why is BMS so important for lithium battery solar street lights?

Answer: BMS is the "intelligent manager" of lithium battery. The absence of BMS will lead to three major risks: First, overcharging or overdischarging of a single battery cell will accelerate the overall degradation; Second, it is impossible to monitor the temperature, and thermal runaway may occur at high temperatures. Thirdly, there is no fault alarm. Battery faults are difficult to detect in time, which eventually leads to the solar street lights stopping. High-quality BMS can extend the lifespan of lithium battery by 30% to 50%.

Will the battery capacity of lithium battery solar street lights be affected by the seasons?

Answer: Yes. When the temperature is low in winter (< 0℃), the capacity of LiFePO4 battery will decrease by 5% to 15% (for example, a 120Ah battery may drop to 102 to 114Ah), but through the BMS low-temperature protection function (limiting the discharge current), basic battery life can be guaranteed. When the temperature is high in summer (above 45℃), if the heat dissipation is poor, the capacity will temporarily decrease by 3% to 8%, and it can be restored after the temperature drops. It is recommended that when selecting the model, an additional 10% capacity be reserved for extreme seasons.

Is there a difference in installation cost between lithium battery and lead-acid battery for solar street lights?

Answer: Yes. The installation cost of lithium battery is lower: On the one hand, the weight of lithium battery is only one-third that of lead-acid battery, and there is no need for heavy lifting equipment. The labor installation cost can be saved by 40% to 60%. On the other hand, lithium battery can be hung on the back or embedded in the light post box without the need to separately pour a concrete base (lead-acid battery require a base, and the cost of a single base is about 80 to 120 US dollars). The overall installation cost is 100 to 180 US dollars lower per set than that of lead-acid battery.

How to determine whether the battery of a lithium battery solar street light needs to be replaced?

Answer: Replacement is required in the following three situations: First, the capacity attenuation exceeds 30% (for example, for a battery with a nominal capacity of 120Ah, the actual discharge capacity is less than 84Ah), and the battery life is shortened to less than 70% of the designed value; The second issue is that the BMS frequently reports "capacity attenuation faults", and the problem remains unsolved even after multiple calibrations. Thirdly, the battery may suffer physical damage such as bulging, leakage, and cracking of the casing, posing safety hazards. Under normal use, the battery replacement cycle of LiFePO4 is usually 8 to 10 years.