How Long Do Solar Batteries Last? Years, Cycles, and Hours Per Charge

A lithium iron phosphate (LiFePO4) solar battery lasts about 10 to 15 years or more, and a flooded lead-acid battery lasts about 5 to 8 years. The batteries we carry are rated for 6,000 to 8,000 cycles (lithium) versus 1,900 cycles (lead-acid), with warranties up to 15 years. On a single charge, a 16 kWh battery runs about 1,000 watts of essentials for roughly 14 hours.

"How long" means two things, so this guide covers both: how many years a battery lasts, and how many hours it runs your house per charge.

How many years do solar batteries last?

Battery life is rated in cycles. One cycle is one full charge and discharge. Here is what the manufacturers rate the batteries in stock at Krato Power:

Lithium figures are from each product's spec sheet. Trojan figures are from Trojan's SPRE 06 415 data sheet.

Turning cycles into years

• 6,000 cycles at one full cycle a day is about 16 years on paper.
• 8,000 cycles at one cycle a day is about 22 years on paper.
• 1,900 cycles at one cycle a day is about 5 years, and that is only using half the battery each day.

Batteries also age with time, not just use, so plan on the warranty term as the realistic life: about 10 to 15 years for lithium. A battery that only covers outages cycles far less than one that runs your house every night, so backup-only batteries usually reach the long end.

Lithium vs lead-acid: why the gap is so big

• Depth of discharge: lead-acid lasts longest when you use about half its capacity. To get 5 kWh a night from lead-acid, you buy about 10 kWh of batteries. Lithium is built to use most of its rated capacity every cycle.
• Maintenance: flooded batteries need regular watering and equalizing. LiFePO4 batteries have a built-in battery management system (BMS) and no watering.
• Upfront cost: lead-acid costs less per battery. Lithium costs more up front but lasts several times as many cycles.

Compare both types in our solar batteries collection.

What shortens a solar battery's life?

• Temperature. Cycle ratings are tested around 77°F. Lithium also has charge limits: the Deye battery, for example, charges between 32°F and 131°F. Keep batteries indoors or pick a heated model for cold garages.
• Deep daily cycling. Every cycle uses up part of the rated cycle life. Daily solar cycling wears a battery faster than backup-only use.
• Lead-acid left partly charged. Flooded batteries lose capacity if they sit undercharged or run low on water.

How long will a solar battery run my house?

Use this formula: usable kWh x 0.9 / load in kW = hours. The 0.9 accounts for about 10% lost in the inverter. If a spec sheet lists a smaller usable capacity than its rated capacity, use the usable number.

• Essentials (about 1,000 W): fridge, lights, Wi-Fi, a furnace blower. A 16.1 kWh battery like the MNPOWERFLO16 runs that for about 14 hours (16.1 x 0.9 / 1 = 14.5).
• Whole house: the EIA puts the average U.S. home at about 899 kWh a month, or about 30 kWh a day. The same 16.1 kWh battery covers about half a day of normal use.
• With solar: panels recharge the battery each day, so a right-sized system can carry essentials through a multi-day outage.

For full sizing, see How Big a Battery Do You Need to Run a House?, or shop battery backup for home.

Need help sizing? Call 1-888-855-7286. Tell us what you need to run during an outage and we will match you to the right battery.

When should you replace a solar battery?

• It no longer gets you through the night or the outage it used to.
• Your monitoring app or BMS shows capacity well below the original rating.
• It reaches the end of its warranty term and is losing capacity. Check what capacity your warranty guarantees at the end of the term.
• For lead-acid: cells will not hold a charge or specific gravity readings stay low after equalizing.

Solar battery lifespan FAQ

How long do solar batteries last? LiFePO4 lithium batteries last about 10 to 15 years or more, with ratings of 6,000 to 8,000 cycles. Flooded lead-acid batteries last about 5 to 8 years.

How many years is 6,000 cycles? About 16 years at one full cycle per day. Fewer cycles per day means more years, though age still wears the battery.

Do solar batteries last longer if they are only used for backup? Yes. A backup-only battery may go weeks without a full cycle, so it uses up its cycle life much more slowly.

How long will a 10 kWh battery last during a power outage? About 9 hours at a 1,000 watt load (10 x 0.9 / 1), or about 4.5 hours at 2,000 watts.

Is lithium or lead-acid better for a home battery? Lithium lasts several times as many cycles, uses more of its capacity, and needs no watering. Lead-acid costs less up front and still works well for budget off-grid banks.

More on rack batteries: How Long Do Server Rack Batteries Last and What They Cost.

Shop Battery Backup for Home