Estimate how many years your solar battery will last based on rated cycle life and daily cycling frequency. Plan battery replacement timing and costs.
Every battery has a finite number of charge-discharge cycles before it degrades below useful capacity (typically defined as 60–80% of original). The rated cycle life at a given depth of discharge tells you how many full cycles the battery can perform over its lifetime.
For solar applications, most home batteries cycle once per day — charging from solar during the day and discharging at night. Some configurations cycle more (time-of-use arbitrage) or less (backup-only use). The cycling frequency directly determines how many years the battery will last.
This calculator converts the manufacturer's rated cycle count into an expected lifespan in years based on your cycling pattern. A battery rated for 6,000 cycles at one cycle per day would last about 16.4 years — well beyond most warranties.
Quantifying this parameter enables systematic comparison across facilities, time periods, and equipment configurations, revealing optimization opportunities that reduce both costs and emissions. This analytical approach supports both immediate cost reduction and long-term sustainability goals, helping organizations balance economic and environmental priorities in their energy management.
Knowing your battery's expected lifespan in years helps you plan replacement costs, compare battery options, and evaluate the true lifetime economics of your solar-plus-storage investment. Data-driven tracking enables proactive energy management, helping organizations reduce operational costs while progressing toward environmental sustainability goals and carbon reduction targets. This quantitative approach replaces rough estimates with precise figures, enabling facility managers to identify the most cost-effective opportunities for reducing energy consumption.
Lifespan (years) = Rated Cycles / (Cycles per Day × Days per Year)
Result: 16.4 years
6,000 rated cycles / (1 cycle/day × 365 days/year) = 16.4 years. This battery would likely outlast its warranty (typically 10–15 years). At 1.5 cycles per day (TOU arbitrage), the same battery would last about 10.9 years.
Lithium iron phosphate (LFP): 5,000–8,000 cycles at 80% DoD. Lithium NMC: 3,000–5,000 cycles at 80% DoD. Lead-acid (AGM): 500–1,000 cycles at 50% DoD. Lead-acid (flooded): 1,000–2,000 cycles at 50% DoD. Saltwater: 3,000+ cycles at 100% DoD.
A typical grid-tied solar battery cycles once per day: charging during solar hours, discharging in the evening/night. TOU arbitrage may add a second partial cycle. Backup-only batteries may go weeks without a full cycle, dramatically extending their cycle-based lifespan.
Batteries don't fail suddenly — they gradually lose capacity. Monitor your battery's state of health through the manufacturer's app. Plan for replacement when capacity drops below 70% or when it no longer meets your nightly energy needs.
One full cycle is a complete discharge and recharge of the usable capacity. Two partial cycles (50% each) count as one full cycle. Batteries track cumulative energy throughput rather than discrete discharge events.
Tesla warrants the Powerwall for unlimited cycles over 10 years, with a guaranteed 70% capacity retention. Independent testing suggests 5,000+ cycles before reaching 70% capacity. At daily cycling, that's roughly 13–15 years.
Yes. Shallow cycles (30–50% DoD) cause less stress than deep cycles. A battery rated for 4,000 cycles at 80% DoD might last 8,000+ cycles at 40% DoD. This is why some systems limit cycling depth below maximum.
Batteries degrade over time even without cycling, due to internal chemical reactions. Calendar aging typically limits lithium batteries to 15–20 years regardless of cycle count. A battery that's rarely cycled won't last forever.
Replace when capacity drops below your minimum requirement (usually 60–80% of original). If your 13.5 kWh battery drops to 9 kWh usable and you need 12 kWh, it's time. Most homeowners replace after 10–15 years.
Yes, significantly. Battery costs have fallen from $1,100/kWh in 2010 to $150–$200/kWh in 2025. By the time you need a replacement in 10–15 years, costs are projected to be $50–$100/kWh, making replacement quite affordable.