When you install a solar power plant with batteries, the investment is designed for many years. But a battery from the EU is more expensive, you can get it cheaper in China. This is influenced by a nuance - warranty terms.
Batteries from the EU are supplied through official channels and have a 10-year manufacturer's warranty. This is a standard required by European law. For batteries from China, even if it is the same Deye brand, most importers only offer a 5-year limited warranty. After that, the customer is left without protection.
What the statistics show
- Less than 1% of lithium batteries fail in the first 5 years.
- By the 10th year, 30–35% of batteries lose capacity below the warranty level (usually 70%) or fail completely.
Batteries age differently than inverters, but the trend is similar:
Accelerated degradation after 5–6 years, especially under high loads or temperatures.
Typical failures: cell imbalance, BMS errors, overheating — most of them are not covered by the warranty after 5 years.
Insurance companies provide the following statistics:
- 35–38% of warranty claims for batteries come between the 6th and 10th years.
- Performance loss of >30% by year 10 is common without proper operation.
Consequences of the lack of warranty
- Full block replacement. Batteries are practically not repairable - in case of failure, you have to buy a new one.
- System downtime. Without a local service, the wait can last for weeks.
- Waste of money and time. Buying a new battery after 5–7 years significantly increases the payback period of the entire solar power plant.