Solar Battery Degradation

How fast do solar batteries degrade?

Solar batteries degrade over time — losing capacity with each charge cycle. Typical degradation: 1-3% per year (lithium-ion). After 10 years: 70-90% original capacity remaining. After 15 years: 60-80%. After 20 years: 50-70%. Manufacturer warranties: Tesla Powerwall — 70% at 10 years. GivEnergy — 60% at 10 years (12,000 cycles). BYD — 60% at 10 years. What affects degradation: (1) Temperature — keep batteries in cool, ventilated spaces. (2) Depth of discharge — avoid regularly draining to 0%. (3) Charge rate — slower is gentler. (4) Cycles per day — more cycles = faster degradation. Even at 70% capacity after 10 years, a 10kWh battery still provides 7kWh — enough for most evening needs.