---
title: Solar Battery Lifespan and Replacement Costs
description: How long a home battery really lasts, what shortens it, and what replacement costs in 2026, before the warranty conversation starts without you.
image: https://cleanvolts.co.za/hubfs/CleanVolts%20Battery%20lifespan%20and%20replacement%20cost.png
---

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# Battery lifespan and replacement cost

![Tony Lopes](https://cleanvolts.co.za/hs-fs/hubfs/clean%20volts%20launch%20post.png?width=48&height=48&name=clean%20volts%20launch%20post.png)

 Tony Lopes

September 28, 2026

If you're like most solar owners in Johannesburg, your battery went in during 2022 or 2023 to get you through load shedding. For its first couple of years it worked a few evenings a week, then sat full and waited for the next outage.

That's not its job any more. In 2026 most batteries run every single night, storing the day's solar so you don't buy expensive evening power from City Power. It's the right way to use the system. But it means the battery is ageing on a different clock from the one it was sold on, and it's now three or four years into a warranty that's probably narrower than you think.

Here's how long a home battery really lasts, what wears it out early, what a replacement costs in 2026, and what to have ready before you ever need to make a warranty claim.

## What "Lifespan" Actually Means

A battery doesn't die on a date. It fades. Each year it holds a little less energy than it did the year before, until one day it no longer covers what you need it to.

Two things wear it down:

- **Cycles.** Every time it's emptied and refilled, it ages a little. One full empty-and-refill is one cycle.
- **Time.** Batteries also age just sitting there. Heat speeds this up a lot.

Manufacturers usually treat a battery as worn out when it holds 60% to 70% of its original capacity. So "end of life" doesn't mean it stops working. A 10kWh battery at 65% is still a 6.5kWh battery. Whether that's a problem depends on whether 6.5kWh still gets your house through the evening.

## How Long a Home Battery Really Lasts

Almost every home battery installed in the last five years is lithium iron phosphate (LiFePO4, or LFP). Manufacturers typically rate them for 4,000 to 6,000 cycles or more, with a 10-year warranty and a design life of around 15 years.

The simple maths: one full cycle a day is 365 cycles a year. At that rate, 4,000 cycles is about 11 years and 6,000 is about 16. Most homes don't do a full cycle every night, so on paper a well-looked-after battery should outlast its warranty.

One local manufacturer puts it plainly: it expects its battery to last about 15 years when it cycles daily, and more than 20 years when it's used only for occasional backup. That gap is the load-shedding-to-tariffs shift in a single sentence. Same battery, very different workload.

If you have an older **lead-acid or gel** system, the picture is different. Those batteries typically last somewhere between three and seven years and don't like being run much below half full. If yours went in before 2020, it's likely near or past the end.

In practice, though, the rated number is a best case. How your battery was installed, where it lives and how it's set up decide whether you get close to it.

## What Shortens It

- **Heat.** The biggest one by far. Batteries age fastest when they're hot. A battery in a closed garage, a roof space, a cupboard with no airflow or against a north-facing wall can spend every summer afternoon well above the temperature it was designed for.
- **Sitting full while it's hot.** Many systems installed for load shedding were set to keep the battery at 100% all day, every day, just in case. A full battery in a hot room ages faster than one that's allowed to work.
- **Being left flat.** Running a battery completely empty and leaving it that way, for example after the grid goes down while you're away, is one of the few things that can damage lithium cells quickly.
- **Settings that don't match the battery.** The inverter should talk to the battery's management system (BMS) and charge it the way its manufacturer specifies. On rushed installs that link is sometimes missing, and the inverter is left guessing from voltage.
- **Being too small for the house.** An undersized battery gets drained hard every night and works at the limit of what it can deliver. Plenty of rush-era systems were sized for whatever was in stock rather than for the house.
- **Mixing old and new.** Adding a new module to an old bank, or mixing brands, can make the whole bank perform like its weakest module. It can also affect the warranty.

## Signs Your Battery Is Ageing

- Backup doesn't last as long as it used to.
- The charge percentage drops quickly in the evening, or the system cuts to the grid while the app still shows charge left.
- The app or the battery's own software shows a **State of Health** (SoH) figure that's falling. Some also show a cycle count. Note both down today so you have something to compare against in six months.
- The system logs battery alarms, especially about cell voltages being out of balance.

**If you see swelling or bulging of the battery case, smell something sweet or like solvent, hear hissing, or the case is hot while the system is idle, don't touch it or try to switch it off up close. Get everyone out of the room and call the fire service on 10177 or 112, and tell them there's a lithium battery on the property.** This is rare, but it's the one situation where speed matters more than anything else in this guide.

## What Replacement Costs in 2026

The good news is that batteries cost a lot less than they did during the rush.

Advertised prices for a single 5kWh LFP module from brands common in Johannesburg homes ran from about R14,500 to R28,000 in September 2026, with most between R15,000 and R22,000. That's roughly R3,000 to R4,500 per kWh of capacity. A typical 10kWh bank, two modules, comes to roughly R30,000 to R44,000 for the batteries alone.

On top of the batteries, budget for:

- **Installation and commissioning** by a registered electrician, including setting the inverter up properly for the new battery.
- **Paperwork.** Battery work is electrical work on your installation, so ask the electrician whether it needs a Certificate of Compliance covering it. We explain why that matters in [your legal duty as a solar system owner](https://cleanvolts.co.za/guides/solar-owner-legal-responsibility).
- **Anything the old install got wrong.** Undersized cables, a missing battery isolator or poor ventilation should be fixed while the work is being done, not carried over to the new battery.
- **Disposal.** Old lithium batteries can't go in the bin. They need to go to a licensed handler.

Two questions before anyone quotes you. Will your inverter work with the new battery? Not every battery talks to every inverter. And is the size still right? A battery sized for load shedding isn't necessarily the right size for cutting your bill.

## Replace, Add, Re-tune or Leave It?

There are four options, and replacing everything isn't always the right one.

1. **Leave it.** A battery at 70% that still covers your evening peak is doing its job. Keep an eye on it.
2. **Re-tune it.** If the system is still set up for load shedding, changing how it charges and discharges can take pressure off the battery and cut your bill. It's usually the cheapest fix. See [tariff re-optimisation](https://cleanvolts.co.za/tariff-optimisation).
3. **Add to it.** Adding modules works best when the existing ones are fairly young and the same model. One manufacturer suggests new modules can go alongside old ones up to about five years or 1,500 cycles, after which replacing is better.
4. **Replace it.** When the battery no longer covers your needs, is showing faults or is unsafe.

The right answer depends on your battery's actual health, which is a number you can measure rather than guess.

## Get Ready for the Warranty Conversation

Most owners first read their battery warranty on the day they need it. By then it's usually too late to fix the gaps. A few things are worth knowing now:

- **It's years or cycles, whichever comes first.** Many warranties end at 10 years *or* a set number of cycles or amount of energy delivered. A battery that works hard every night can reach the cycle limit before year ten.
- **It guarantees capacity, not perfection.** The warranty typically promises the battery will still hold 60% or 70% of its original capacity. A battery that has faded to 75% is usually working as warranted.
- **Some depend on registration.** One widely used brand in South Africa gives a shorter standard warranty that extends to 10 years only if the battery was registered with the manufacturer. Check whether yours was.
- **Claims need evidence.** Expect to be asked for the invoice from an authorised seller, the serial numbers and the battery's own logs. Tamper seals must be intact.
- **Common exclusions.** Mixing with other batteries, not installing it to the manufacturer's instructions, physical damage and lightning are often excluded.
- **Claims usually go through the installer.** If your installer has closed down or stopped answering, you can still approach the distributor, but you'll need the paperwork yourself.

## What to Do This Week

1. **Find the invoice.** The original one, showing the battery model and who sold it.
2. **Photograph the labels.** The model and serial number are on a label on the outside of each module. Don't open anything.
3. **Look up the warranty document** for your model. Note the years, the cycle or energy limit, and the capacity it guarantees at the end.
4. **Check the registration** if your brand offers one.
5. **Open the app.** Write down the State of Health and cycle count if it shows them, and roughly what time the battery runs out on a normal evening.
6. **Check where it lives.** Go and stand next to it on a hot afternoon. If the room is hot and stuffy, that's worth mentioning to whoever looks at your system.
7. **Phone your insurer.** Ask whether the battery is on your policy, and whether lightning and power surge damage are covered.

## How We Help

We check existing solar systems across Blairgowrie, Linden, Randburg, Ferndale, Northcliff, Fairland, Emmarentia, Greenside, Parkhurst and the suburbs around them.

A Solar Health Check reviews your system's data and history, including what the battery has been doing, and gives you a written report of what we found. A Full Solar System Audit goes further, with a battery health assessment using the battery's own data and, where the battery supports it, a controlled capacity check. Monthly [monitoring](https://cleanvolts.co.za/monitoring) tracks battery health over time, so you see the decline coming rather than finding out on a cold evening.

If a battery does need replacing, we specify it, supply the components at cost with the supplier's invoice, and manage the job for a transparent project management fee. The electrical work is done by a registered electrical contractor you contract directly, who issues any certificate in their own name.

## Book a Health Check

Not sure how much life your battery has left? [Book a Health Check](https://cleanvolts.co.za/health-check) and find out before you need to.

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