Is it still worth getting a home battery in Australia if I can’t install solar panels on my roof?

Some households aren’t suited to solar – but do batteries make environmental or financial sense on their own?

Many people want to reduce their carbon footprint but for various reasons can’t install solar panels. Some roofs face the wrong way, others are overshadowed or subject to heritage restrictions, and apartment blocks often lack space.

Landlords are also often reluctant to install solar systems in rental properties since the benefits flow to the tenants rather than the property owner.

So is there value in installing a battery anyway?

Financial cost v environmental benefit

David Collins, a retiree, wanted to install solar, but his roof is shaded by an old tree in the back yard.

Instead, inspired by local community group Electrify Mackellar, Collins spent $14,000 on a 15 kilowatt hour (kwh) battery. He’s saving about $100 a month on electricity bills, so his investment will take 12 years to pay off – longer than the battery’s 10-year warranty.

But the resident of Sydney’s bushfire-prone Northern Beaches thinks it’s a good deal because the battery provides backup power if he’s isolated from the electricity network.

“We’ve had trees come down and take out the power lines,” he says. “I wanted to be self-sufficient in case of a power outage.”

Collins’ retailer provides 100% renewable energy and buys back power at peak times. The battery is set to automatically draw from the grid when electricity is cheap in the middle of the day and enables Collins to sell power later when prices rise, booking a modest profit.

When we speak, just after 4pm, Collins checks an app that shows his electricity price is 24 cents per kwh. “That’s quite expensive,” he says. “Earlier today I was paying nine cents.” A separate app tells him his house is now drawing power from the battery.

“It’s really a brilliant system,” says Collins, though he stresses his primary motivation for getting a battery was environmental, not financial.

I tried to figure out whether we could do something similar in our Melbourne apartment.

Our electricity retailer offers a time-of-use tariff of 9 cents per kWh between 10am and 3pm. Outside those hours, we pay about three times as much.

In theory, if we filled a battery with discount power during the middle of the day and drew on it the rest of the time, we could have non-stop cheap electricity. We’d reduce emissions, soak up excess renewable energy and ease pressure on the electricity network when demand peaks.

Rough calculations show that a battery would take more than 17 years to pay for itself. Given that batteries last about 15 years, this isn’t a great deal.

What subsidies are available?

Labor is promising big subsidies for home batteries if it wins the election, but they would only apply to households with solar panels that buy batteries that can be networked as part of a “virtual power plant”, feeding electricity into the grid to balance supply and demand in real time.

The Greens and independent MP Sophie Scamps also have household battery proposals, but the Coalition is yet to offer one.

If our household qualified for Labor’s subsidy, the payback time would fall to a little over 12 years, making it closer to break-even. Double dipping with state-based home battery schemes could make it more viable still, as would selling power back into the grid.

So why not extend subsidies to homes without solar?

Ben McLeod, an analyst at the Climate Council, thinks it is wise to prioritise homes with solar because it is a big enough market to make a real impact.

“Storing energy where it is generated and used also keeps excess power out of the grid,” he says. “That’s especially important in areas where high solar uptake is already pushing the limits on new connections.”

McLeod thinks there are more cost-effective ways for households without solar to support the transition to renewable energy, such as heating hot water during the day instead of at night.

What about renters?

Tristan Edis, the director of the analytical and consulting firm Green Energy Markets, says people who install solar panels and batteries are paying a share of the upfront cost of a shift to renewables that is reducing wholesale energy prices. “They help all energy consumers to a degree,” he says.

The Smart Energy Council has backed a Greens’ proposal to give renters access to solar panels. It says the case for installing batteries without solar will get stronger as batteries become cheaper and more efficient.

Edis says it’s also worth investigating the potential of combining portable batteries with balcony solar for renters and people living in apartments. This is popular in Germany but faces regulatory hurdles in Australia.

David Collins is keen to eventually power his battery with rooftop panels. “I would love to go completely solar,” he says. “That old tree in back yard might need to come down one day, and when that happens, I will.”