Solar battery lifespan: how long a home battery lasts in Melbourne

How long do solar batteries last?

A battery’s life is counted in years and in the energy it delivers. One full cycle is charging it to full and using all of it. Charged by solar, a battery fills at most about once a day, and less often in winter.

Five of the eight makers we compared cap the guarantee with a throughput limit: the total energy, in megawatt-hours (MWh), the battery may deliver. Divide it by the usable capacity to get full cycles. GoodWe’s 46.72 MWh on a 12.8 kWh Lynx Home F G2 is about 3,650 cycles: 10 years at one a day. Sungrow and Tesla set none for self-consumption and backup.

Datasheet cycle life is not the warranty

Some datasheets quote their own cycle life: Sigenergy 10,000, from a cell test down to 60% of capacity (its warranty covers about 3,046); GoodWe more than 4,000, from a cell test down to 80% of capacity (its warranty covers about 3,650). Those are lab tests of cells. Compare batteries on the warranty: it is the figure the maker stands behind.

Estimate your yearly cycles

What does a battery warranty guarantee?

A battery warranty covers defects and promises how much capacity the battery keeps. The last column shows when each energy limit would arrive if the battery did one full cycle every day, which a solar battery rarely does. At that rate Alpha ESS, BYD and Sigenergy would reach theirs before the 10-year term ends. For Fox ESS and Enphase the limit ends the whole warranty; for the others, only the capacity guarantee.

Sungrow and Tesla allow unlimited cycles only for the uses their warranties list, such as self-consumption and backup. Any other use, or a mix that includes one, has a throughput limit (Sungrow: 35.84 MWh for other uses on an SBR128; Tesla: 37.8 MWh for any other use). Neither warranty mentions a virtual power plant, so if you join one, ask the maker how its use counts.

Offline and registration clauses

All eight warranties want the battery registered, monitored or online. Two spell out the cost of going offline:

• Tesla: If it isn’t registered, or stays offline for an extended period, Tesla says it may honour only 4 of the 10 years.
• Sigenergy: Must stay online: over a year disconnected cuts the term to 5 years.

Solar and battery warranties

Solar battery types: LFP, NMC and sodium-ion

All eight batteries we compared are lithium battery systems with lithium iron phosphate (LFP) cells, by the makers’ documents and the approved list. The approved list is lithium too: the Clean Energy Council describes it as over 1,000 lithium-based batteries. When we read every row in November 2026, the only model labelled nickel manganese cobalt (NMC) was the LG RESU6.5, and one, the Zenaji AEON, was lithium titanate. We don’t rank chemistries: the warranty shows how each maker expects its cells to age.

Sodium-ion batteries in Australia

Sodium-ion cells store energy with sodium in place of lithium. None was on the approved list when we read it in November 2026. For the federal rebate a battery must be included on the Clean Energy Council (CEC) approved battery list, so check a sodium-ion model is listed before you count on the rebate. Standards Australia’s new safety specification, SA TS 5398, published 3 October 2025, adds lead acid batteries and leaves room for other technologies later; the Clean Energy Council is moving its list to it.

Lead-acid, flow and salt-water batteries

You won’t find these older or niche chemistries in a rebated quote for a grid-connected Melbourne home. The reason is the rebate: every chemistry the approved list named was lithium-based when we read it in November 2026, and no row named lead-acid, flow or salt-water, so you can’t count on the federal battery rebate for one today. That may change for lead acid as listings are made under SA TS 5398.

How the battery rebate works

What does a battery management system (BMS) do?

The battery management system is the electronics that watch the cells. The Clean Energy Council’s Battery Safety Guide defines a battery module as “one or more cells linked together. A battery module may also have incorporated electronics for monitoring, charge management and/or protection.” Sungrow’s SBR datasheet, for example, lists over and under voltage, over current and over and under temperature protection. The BMS is why a battery may hold off charging on a cold morning, and why makers want it online: they read its data and update its firmware remotely.

Modular vs fixed-size batteries

A modular home battery is a stack of modules on one controller or inverter, so it can be built at several sizes and grow later. Six of the batteries we compared work this way, in steps from 2.56 or 2.76 kWh (BYD) to 9.3 kWh (Alpha ESS). Enphase and Tesla sell fixed-size units of 5 kWh and 13.5 kWh and grow by adding whole units.

The limits of a modular battery system

• A minimum size. BYD, GoodWe, Sungrow and Fox ESS start at two modules or more, so the smallest system isn’t one module.
• The inverter caps the stack. GoodWe’s Lynx Home F G2 stack goes to 28.8 kWh, but at most 22.4 kWh on GoodWe’s single phase EHB inverter and 19.2 kWh on its EH.
• The inverter sets the power. Fox ESS, GoodWe and Sungrow rate the battery higher with each module, but the inverter decides what reaches the home.
• Weight and floor space. A floor-standing stack gets taller and heavier with each module: the Sungrow SBR goes from 89 kg to 279 kg (sizes and weights).
• More connections. Every module adds connectors and cabling for the installer to make and check.

Adding modules later

Adding capacity years later mixes new modules with aged ones, and makers limit that (GoodWe: within a year of installation); read the maker’s warranty on additions before you plan one. The federal rebate allows one battery claim per property: an addition can claim only if the first battery didn’t, and only if it adds at least 5 kWh. So size the battery for your evening use the first time.

Compare battery sizes

Heat, cold and where it’s mounted

Each maker sets the temperatures its battery runs in, down to −20 °C for six of the eight. For a Melbourne winter the charging limits matter more: Fox ESS, GoodWe and Sungrow don’t charge below 0 °C, so on an exposed wall on a frosty morning the battery waits until it warms. Some slow down above freezing: BYD derates power below 5 °C and Enphase charges at reduced power below 15 °C. In summer, Enphase charges at reduced power above 45 °C and Tesla may de-rate performance above 40 °C.

A garage or a wall out of the afternoon sun keeps a battery nearer the middle of its range. The spot must also suit its rating and AS/NZS 5139:2019, which never allows a battery inside a habitable room, or in a ceiling space or wall cavity.

Where a battery can go

Are solar batteries safe?

An approved battery that is installed and inspected properly has passed several safety checks, though faulty products do get recalled. To get the rebate, its model must be on the Clean Energy Council list of batteries that meet its Battery Safety Guide (moving to SA TS 5398). It must be installed to AS/NZS 5139:2019, and in Victoria an independent licensed inspector checks the work before it is switched on.

Does a home battery need a smoke alarm?

The standard recommends one. Solar Victoria’s Notice to Market 2025–26 explains its own rule this way: “It is recommended to install a smoke alarm in the same room as an energy storage solution in the battery installation standard AS/NZS 5139.” For batteries installed under its solar battery loans (closed to new applications in May 2025), it is mandatory: where the battery is in “a room under the same roof as a residence (e.g. a garage or storeroom)”, a smoke alarm in that room to AS 3786:2014 or AS 3786:2023, ideally hard wired and interconnected with the home’s other smoke alarms, or with some other alert inside the home. Where “the use of the area is likely to result in smoke alarms causing spurious signals”, detection to the fire detection standard AS 1670.1 takes its place. Victoria’s general law, as Fire Rescue Victoria sets it out, asks for at least one smoke alarm on each level of a house and alarms between each sleeping area (bedroom) and the rest of the house; it doesn’t name the room a battery is in. If your battery goes in an attached garage, ask for one in your quote.

Keeping a home battery safe, and what to do if it alarms, smells, swells or smokes

• Keep it online and registered. Warranties, firmware fixes and recall notices depend on it.
• Don’t leave it flat. Sigenergy’s datasheet: “Battery must be recharged within 7 days after being fully discharged to keep battery healthy.”
• Keep the space around it clear. No boxes, paint tins or fuel stacked against or on it, and nothing over its vents.
• Know where its shutdown sign is. Solar Victoria’s guidance counts it among the most important labels: a site-specific shutdown procedure, next to the inverter the battery connects to and visible from the switches it tells you to operate.
• Act on alarms. If the app shows a fault, call your installer. Look, don’t touch: only a licensed electrician should work on it.

Fire Rescue Victoria’s lithium-ion advice lists the warning signs: strong odours, colour change, extreme heat, change in shape, leaking or unusual sounds (for example popping or hissing). If a home battery shows them, keep away and call your installer. If it smokes or burns, get everyone out: “If your battery catches fire ring 000 immediately and wait in a safe location for firefighters to arrive.” Use the shutdown procedure only if you can reach it safely.

Where a battery can go

Home battery and hybrid inverter recalls: Sigenergy, GoodWe, Tesla and LG

Recalled LG cells may sit inside SolaX, Opal, Redback, Red Earth, Eguana and VARTA systems, so use LG’s serial-number check even if your battery isn’t LG-branded. Energy Safe Victoria: “If a battery is subject to recall, it should be switched off immediately.”

Inspection and approvals

End of life: replacement and recycling

There is no set replacement date: the warranty promises a floor of 70% at 10 years, not an end date. Replace the battery when it no longer covers enough of your evening use, or when it develops a fault outside warranty.

An old battery can’t go in a bin. Solar Victoria counts solar panels, inverters and energy storage equipment at the end of their useful life as e-waste, which Victoria bans from landfill. EPA Victoria warns: “Lithium Ion batteries can cause fires if disposed of incorrectly.” Solar Victoria says retailers must make sure decommissioned equipment is removed from customers’ homes, and recommends recycling certified to AS 5377.

Removing old solar and batteries

What a new battery costs

Battery lifespan and safety: your questions