Is a Solar Battery Worth It? The September 2026 Answer

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We get asked this most weeks. The honest answer is that for some houses it stacks up now, and for others it does not yet. Here is how we work it out, with the numbers as they stand in September 2026.

What has changed this year

Feed-in tariffs. South East Queensland has no regulated minimum, and what we see on customers' bills is all over the place. Some plans pay 3c per kWh. Some now charge you to export in the middle of the day. Exporting is worth very little, and on some plans it costs you.

Grid power. The regulator's headline for this year was a price drop. We have not seen it on a single customer bill. Usage rates run from around 30c up to 55c per kWh depending on the plan, and supply charges from about 90c up to $2.20 a day. The two tend to trade off. The plans charging 55c for usage usually have supply around 90c, and the cheap usage plans make it up on supply. A battery cuts the usage side of the bill. It does nothing about the supply charge.

The rebate. The federal Cheaper Home Batteries Program went to a tiered structure on 1 May 2026. The first 14kWh of usable capacity gets the full rate, the next block gets a reduced rate, and above 28kWh you get very little. The certificate rate is 6.8 per kWh until the end of December. It steps down again on 1 January 2027.

The maths, plainly

Every kWh of solar you store instead of exporting, then use that night, saves you the gap between what you would have paid and what you would have been paid. On a 30c plan that is around 27c for every kWh you store. On a 55c usage plan it is closer to 50c, and that is where a battery starts to make real sense.

A 10kWh battery cycled most days shifts somewhere around 8 to 9kWh a day averaged across the year after cloudy runs and short winter days. Call it $800 a year on a 30c plan, and closer to $1,500 a year on a 55c plan.

On a time-of-use tariff, with peak pricing from 4pm to 9pm, the gap is wider and the saving is higher. If you run a pool pump, ducted air conditioning in the evening, or charge an EV overnight, the battery does more work and pays back faster.

Set against the installed price after the rebate, straight bill payback on a 30c plan with modest evening use is often past ten years. On a high usage rate plan, or time-of-use with a heavy evening load, it comes in well under that. And ten years is not the end of the battery, which is the next point.

How long a battery actually lasts

This is where the ten year payback number gets misread. A ten year warranty is not a ten year life.

The lithium iron phosphate batteries we install are rated for somewhere between 6,000 and 10,000 cycles. One full cycle a day is 365 a year, and most home batteries do fewer than that once you count cloudy days and light-use days. At 6,000 cycles you are looking at 16 years or more. At 10,000 it is past 25. Sigenergy's cells, for example, are rated to 10,000 cycles by the cell maker. Calendar age catches up before the cycle count does, so 15 to 20 years of useful service is the realistic expectation rather than 27.

Degradation is real, but it is gradual. The warranties on the GoodWe, Sigenergy, Sungrow and Tesla systems we install all guarantee at least 70% of original capacity at the ten year mark. A 10kWh battery still holding 7kWh or more in year ten is still shifting most of your evening load, and it keeps doing that after the warranty ends. The battery does not stop on its tenth birthday. It just holds a bit less.

So when you work out payback, count the years after the warranty as well. On a 30c plan that turns a marginal case into a reasonable one. On a 55c plan it was already there.

What the numbers do not capture

Backup. Storm season on the Sunshine Coast means outages, and a battery set up for backup keeps the fridge, lights, internet and some power points running. Whole-home backup is possible on some systems, essential circuits on others. It is not a dollar figure, but for a lot of households it is the actual reason they buy.

Where power prices go over the next ten years is the other unknown. They came down this year. I would not plan on that, and I am not going to forecast it either way.

When we tell people not to bother yet

• Low evening usage. If you use under 8kWh between sunset and sunrise and you are on a cheap usage plan, a big battery will sit half full. A smaller one, or waiting, is the honest advice.
• Undersized solar. A battery with nothing to charge it in winter does not save you much. Sometimes the right answer is more panels first, or both at once.
• A cheap battery. There are plenty on the market. We do not install them. A battery that fails in year six has a worse payback than no battery at all.

How to get a straight answer for your place

Pull your last twelve months of usage from your retailer's app, ideally the half-hourly data if you have a smart meter. We look at your evening load, your tariff, what solar you already have, and what your switchboard needs. The person quoting is a qualified electrician. If it does not stack up for your house, we will tell you.

Questions we get asked

Can I add a battery to my existing solar system?

Usually, yes. If your inverter is a few years old we can AC couple a battery alongside it, or replace it with a hybrid inverter and keep the panels. Which way to go depends on the age and size of what you have. We design around what is already there rather than starting again.

Should I just switch to a cheaper electricity plan instead?

Do both. Switch to the best plan for your usage first, then work out the battery on those numbers. A battery on a cheap usage plan still saves you money, it just takes longer. A battery on a 55c plan you never got around to changing is paying for someone else's problem.

Will the battery run my house in a blackout?

Only if it is set up for backup, and that is not automatic on every system. Essential circuits, meaning lights, fridge, internet and some power points, is the common setup. Whole-home backup is possible on some systems but ducted air conditioning and electric ovens will drain a battery fast. Tell us what you want to keep running and we will design for it.

How big a battery do I need?

Work off what you use between sunset and sunrise. For most homes on the Sunshine Coast that is 10 to 20kWh. Your retailer's app or a smart meter download will show it. Buying more than you can fill in winter is money sitting on the wall.

Can I get the rebate if I already have solar?

Yes. The Cheaper Home Batteries Program rebate is on the battery, not the panels. It applies to new or existing solar, one rebate per property, and it has to be installed by an accredited installer to be claimed. If your existing battery has already had the rebate, adding modules to it will not get a second one.

Should I wait for battery prices to come down?

Battery prices have been coming down, but the rebate has been stepping down at the same time, so the price you actually pay has stayed about the same. The next rebate step is 1 January 2027. If you wait, you are betting the hardware drops faster than the rebate does, and so far it has not. You also pay full price for another summer of evening power in the meantime. If your numbers stack up now, waiting rarely improves them. If they do not stack up, waiting is fine and we will say so.