Solar Energy Storage Systems — How to Make Your Lithium Batteries Last Longer
Dec 15, 2025
"How to maintain and extend the lifespan of lithium batteries in a solar system"—is this something you've always been concerned about? Lithium battery maintenance requires consideration of many factors, such as charge/discharge management, environmental control, system compatibility, and daily monitoring. Below is a system maintenance guide:
1. Core Principles: Avoid "Three Highs and Two Lows"
Three Highs: High-rate charge/discharge, high/low temperature environments, and long-term storage at high capacity (100% SOC).
Two Lows: Over-discharge (low SOC), and low-temperature charging (below 0°C).
2.Charge and Discharge Management (The Most Critical Aspect)
(1) Avoid Over-Discharge
Set a reasonable discharge cutoff voltage (e.g., the voltage of a single lithium iron phosphate cell should not be lower than 2.5V). The system needs to be equipped with a BMS for protection.
It is recommended to maintain the battery level between 20% and 90% during daily use to avoid prolonged periods of low charge.
(2) Optimize Charging Strategy
Use multi-stage charging (constant current-constant voltage-float charging) to avoid prolonged high-voltage float charging.
Control the charging current between 0.2C and 0.5C (e.g., charge a 100Ah battery with 20A~50A) to reduce high-current surges.
Avoid low-temperature charging: Charging below 0°C can easily lead to lithium deposition, requiring regulation through a BMS or heating system.
(3) Shallow Charge and Discharge
Controlling the battery's depth of cycle (DOD) to below 70%~80% can significantly extend cycle life (e.g., using only 50% of the battery level per day may more than double the lifespan compared to using it at 100%).
3.Environment and Installation & Maintenance
(1) Temperature Control
Ideal Temperature: 15°C~25°C (Optimal charging/discharging range).
(2) High Temperature Protection:
Avoid direct sunlight; ensure proper ventilation in the battery compartment.
When the ambient temperature is >35°C, consider active cooling (fan/air conditioning).
(3) Low Temperature Protection:
Stop charging below 0°C; if necessary, install insulation or a self-heating BMS.
In extremely cold regions, consider underground insulated boxes or indoor installation.
(4) Installation and Connection
Keep the battery pack dry and clean, avoiding dust or corrosive gases.
Regularly check the tightness of cable connections to prevent poor contact leading to localized overheating.
When using batteries in parallel, select batteries of the same model and batch to ensure consistent internal resistance.
4.System Co-optimization
(1) The Importance of BMS (Battery Management System)
Individual cell voltage/temperature monitoring
Overcharge, over-discharge, overcurrent, and short-circuit protection
Temperature balancing function (active balancing is preferred)
Regularly check cell consistency via the BMS; if the voltage difference is >50mV, investigate the cause.
(2) Load Management
Avoid sudden high-power loads (such as motor starting); a soft starter can be installed.
Power design should include a margin to prevent prolonged high-rate discharge.
5.Daily Monitoring and Maintenance
(1) Regular Inspections
Monthly inspections of battery appearance (bulging, leakage), temperature, and connection terminals.
Quarterly capacity degradation analysis using BMS data (capacity tester available).
Annual professional testing: internal resistance test, equalization maintenance.
(2) Long-Term Storage Recommendations
If the system is not used for an extended period, maintain the battery charge at 40%~60% (half-charge state).
Disconnect the battery from the system and perform a top-up charge maintenance every 3 months.
Through the above measures, the key to maintaining and extending the lifespan of lithium batteries in solar energy systems lies in prevention rather than remediation. Keeping the batteries operating in their "comfort zone" is the most cost-effective maintenance method.
