Is a household solar battery right for me?

Chris Williams , CEO & Founder speaks with

Is a household solar battery right for me?

Is a home battery for me?

Even with a subsidy and low-interest loans, purchasing a home battery and, for some households, new solar panels, is a financial commitment that will take a number of years to reap returns and justify the initial investment. For that reason, asking the right questions at the outset is vital to ensure the right outcomes.

Chris Williams, chief executive officer of qualified system provider Natural Solar, says the key questions range from the financial to the philosophical. He says for those who have neither a home battery nor solar panels, the first question is simple: “Do you have available roof space for solar panels because, if you don’t, the battery is redundant.”

If your roof allows for enough access to sunlight to warrant the installation of panels, he says the next step is to grab a copy of your latest electricity bill and find out how many kilowatt hours of power you use each day. Then assess how much of that power you use during daylight hours and how much at night.

“What we are trying to drag out of the data is how much power is the household using at night when the solar is not operating and can we generate enough during the day to store that throughout the day in the battery to discharge in the evening,” Williams says. “If you are using less during the day and more at night, you would gravitate towards a larger battery.”

For smaller households who consume less power in general, a smaller battery may be in order, although Williams warns that depending on the size of electricity bills, such households may find it harder to break even on their investment. For the rare households that do not use any power at night, a battery is pointless.

“Most people use about 65 to 70 per cent of power in the evening and therefore a large battery does make sense,” he adds.

Overall, planning ahead for a household’s future energy needs is key: “Do we expect electricity consumption to increase? Are you perhaps looking at an electric vehicle, do you have kids who are getting older and perhaps using more power, might there be someone at home during the day using power? These are the variables to consider,” he says.

If you decide a battery is for you, consider whether you have a suitable place for it. Battery systems can’t be installed in habitable rooms – including a lounge, dining or bedroom – with garages the preferred site. If you have no space undercover, an outdoor enclosure may have to be built, usually on the outside wall of your house. Williams also recommends you consider the goals of your household: “Is your motivation purely a reduction in carbon emissions? That changes the weight of the financial return in your equation. Or is the motive purely to get your electricity bills down to make the system cash-flow positive?”

In that case, he advises comparing how much your energy costs will fall post solar and battery installation and consider whether you will at least break after paying off the finance used to pay for the scheme over a number of years. “Is the cost of the finance and principle actually going to be less than the saving on the bill?” he asks. “Quite often it’s ‘yes’, with the help of the subsidy, in which case you are cash flow positive and you own the asset after five to seven years.”

Williams says the best return on investment on a solar and battery system his company was observing outside of South Australia was six to eight years. “It’s really exciting to see that extra subsidy up to $6000, which pushes it over that tipping point which gets a five to five and a half year return on investment for a technology that does last for warranteed period of 10 years but is expected to last for 20 years,” he says.

While any South Australian household connected to the grid is eligible for a subsidy, not everyone will be eligible for the extra low-interest finance. Only those with the capacity to repay the loan will qualify. He says households who currently have the benefit of a very generous feed-in tariff under an old scheme should note that they will lose access to that subsidy when they install a battery.

What’s in a battery?

Consider what you are looking for in a battery. Each battery has a specific cycle life – the period in which a battery is fully charged and then discharged is one cycle – and some batteries guarantee more cycles over their lifetime then others. These are usually more expensive but should last longer and give you a better return on investment. “The return on your investment might be over seven or eight years, but what about after that?” Williams asks. “How long will that system actually function for? The longer it works the greater the return you are going to get.”


Household storage: 5kWh

Subsidy: up to $3000

$500/kWh for non-concession

$600/kWh for concession.


Household storage: 7.5kWh

Subsidy: up to $4500

$500/kWh for non-concession

$600/kWh for concession


Household storage: 10kWh

Subsidy: up to $6000

$500/kWh for non-concession

$600/kWh for concession

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These costs are based on the SA Power network in Adelaide but prices may vary depending on your circumstances. This comparison assumes a general energy usage of 4000kWh/year for a residential customer on Energy Locals Time of Use Tariff – (TOU – Peak, Off-Peak & Solar Sponge).

The reference price is set by the Australian Energy Regulator (AER) for a financial year in relation to electricity supply to residential customers in the distribution region and is based on an assumed annual usage amount. Any difference between the reference price and the unconditional price of a plan is expressed as a percentage more or less than the reference price. The terms of any conditional discounts are shown, along with any further difference between the reference price and the discount applied if a condition is met, expressed as a percentage more or less than the reference price.