If you’re considering adding a battery to your home solar system, you’re going to want to know– how long will it last? A home solar battery is a significant investment, and knowing what to expect in terms of lifespan and performance can help you decide whether it’s worth it.
Modern home batteries, like the FranklinWH aPower 2, Enphase IQ Battery 5P, and Tesla Powerwall, are built with lithium iron phosphate (LFP) chemistry, which is known for its long lifespan, efficiency, and safety. Here’s what you need to know about how long these batteries last and what you can expect from them.
How Long Will a Solar Battery Last?
Older solar batteries using flooded lead-acid or AGM technologies would often need replacing in a few years.
Most modern solar batteries today use lithium iron phosphate (LFP) chemistry and last between 10 to 15 years, with warranties covering a certain number of cycles or a specific timeframe. While your solar panels might last 25 to 30 years, a battery will likely need replacement at least once during that time, but it’s a massive improvement over older systems.
Average Lifespan of Common Solar Batteries
| Battery Type | Average Lifespan |
|---|---|
| Flooded Lead-Acid (FLA) | 3-7 years |
| Absorbent Glass Mat (AGM) | 4-10 years |
| Lithium-Ion (NMC) | 8-15 years |
| Lithium Iron Phosphate (LFP) | 10-20 years |
Battery Lifespan by Model:
- FranklinWH aPower 2 – 15-year warranty, 60 MWh throughput
- Enphase IQ Battery 5P – 15-year warranty, up to 6,000 cycles
- Tesla Powerwall – 10-year warranty, 37.8 MWh throughput
Each of these batteries is designed for daily cycling, meaning they can be used every day for self-consumption, time-of-use savings, or backup power.
What Affects a Battery’s Lifespan?
Several factors impact how long a home solar battery will last:
1. Battery Chemistry
All three of these batteries use lithium iron phosphate (LFP), which lasts longer than older lithium-ion (NMC) or lead-acid batteries. LFP batteries are also safer and more heat-resistant.
2. Usage Cycles & Throughput
Battery lifespan is typically measured in cycles or throughput, depending on the manufacturer. A cycle refers to a full charge and discharge of the battery, and most batteries are rated for thousands of cycles.
Throughput, on the other hand, measures the total amount of energy a battery can store and discharge over its lifetime. For example, a Tesla Powerwall with 37.8 MWh throughput means it can deliver 37,800 kWh of energy before its efficiency significantly declines.
If you cycle your battery daily and use around 10 kWh per day, that would be roughly 10 years of use. Both metrics help gauge a battery’s longevity, with higher values indicating a longer lifespan.
A study by NREL showed that even on modern batteries, a reduction in cycles extends battery life. So if you are not using your battery for self-consumption, and are using it for backup only, you may only cycle your battery a handful of times a year.
Since the batteries are built for daily cycling, backup-only installations may extend their battery life significantly.
3. Depth of Discharge (DoD)
Depth of Discharge refers to how much of a battery’s capacity is used before recharging. Older batteries were severely affected by depth-of-discharge, and it was recommended to never go below 50% in order to avoid damaging them. Fortunately, modern batteries allow for deep discharges without significant wear, due to LFP chemistry.
- FranklinWH aPower 2: 100% DoD
- Enphase IQ Battery 5P: 100% DoD
- Tesla Powerwall: 100% DoD
Even though these batteries allow full discharge, a study found that while LFP tolerates deep discharges better than other forms of batteries, regularly discharging your battery more than 80% does contribute to faster degradation.
If you are using your battery for time-of-use or self-consumption, it may be wise to set a 20% reserve, to maximize your battery’s lifespan. If you are just looking for whole-home backup, then letting it discharge up to 100% during outages should not be a problem.
4. Environmental Conditions
Batteries last longer when stored in temperature-controlled environments. Extreme heat or cold can degrade battery life, but modern batteries are drastically more tolerant than older lead-acid battery banks. Here’s what these batteries can handle:
- FranklinWH aPower 2: -4°F to 122°F (-20°C to 50°C)
- Enphase IQ Battery 5P: -4°F to 131°F (-20°C to 55°C)
- Tesla Powerwall: -4°F to 122°F (-20°C to 50°C)
While these batteries are built for outdoor use, installing them in a garage or shaded area can help maximize lifespan. While they are very tolerant of cold, placing them in a hot shed could shorten their lifespan due to our hot Virginia summers.
LFP batteries are significantly more tolerant of extreme weather than chemistries like NMC or lead-acid, but they can still benefit from a stable, mild temperature.
What Can These Batteries Power?
Home solar batteries vary in size, but here’s a general idea of what they can run:
- FranklinWH aPower 2 (15 kWh) – Can power a home’s essential loads for up to 10 hours, or run a 5-ton air conditioner briefly.
- Enphase IQ Battery 5P (5 kWh) – Works well for smaller loads like lights, refrigerators, and WiFi routers for 6–10 hours (for a fair comparison, it’s worth mentioning that the 5P is scalable, and would typically have 3x units for every one Powerwall or Franklin aPower 2).
- Tesla Powerwall (13.5 kWh) – Can power most appliances, including a fridge, lights, and some HVAC use for 8–12 hours.
Many homeowners install multiple batteries to increase backup power and capacity. For example, two or more Tesla Powerwalls or FranklinWH aPower 2 units can keep large appliances running for a long time.
Final Thoughts
Modern home solar batteries last 10 to 15 years, but their lifespan can be extended (or shortened) depending on how often you use them, and how they’re stored.
If you’re looking for a long-lasting battery, lithium iron phosphate (LFP) options like the FranklinWH aPower 2 and Enphase IQ Battery 5P are our favorite choices. By using your battery wisely and keeping it in a stable environment, you can maximize its lifespan and performance for years to come.
Interested in adding battery storage to your solar system? Get a free battery backup quote today.
