Is your solar battery blackout-proof?

Woman with candle in power blackout

Peter Nugent

Posted October 08, 2019

Forget candles. Solar batteries can keep the power running during a blackout.

As Victorians are being warned to prepare for potential power blackouts this summer, with serious doubts over the reliability of the electricity network, many households are considering installing solar panels with a battery at home.

A renewable energy system charges your battery using the sun’s rays and stores that power in a battery for you to use later.

But those considering buying a battery to protect against possible blackouts should ensure they choose the ‘back-up’ option, says RACV senior product manager energy, Kieran Davies.

Kieran explains that while many newer batteries have a back-up option that allows them to operate in the event of a blackout, not every battery will work when mains power fails.

He says Australian standards require that solar systems connected to the grid shut down in a blackout to prevent power flowing back into the grid, which could endanger electrical workers who may be fixing the problem.

The back-up function, which is standard in many newer battery systems, allows the batteries to operate by ‘islanding’ the whole system and the house from the grid. In the case of a blackout, power to the home will be cut for around 30 seconds while the system recognises the blackout and switches to blackout mode.

“If the power goes out they will be able to keep the lights on and run their refrigerator using the power of the battery,” says Kieran. “However, there is limited capacity, so if they use an air-conditioner or an electric oven this would drain the battery in just a few hours.”

He says there are two main types of backup systems. A whole-of-home backup will allow everything in the house to be powered by the battery in a blackout, but will drain quickly, especially if you continue to use power guzzlers such as air-conditioners. Alternatively, an electrician can set up your battery for essential load backup, by isolating certain circuits to power essentials such as lighting and fridges. This will help the battery charge last longer.

However, Kieran warns that solar batteries are not a UPS (uninterruptible power supply) and are not suitable for people who depend on essential medical equipment.

Some solar batteries automatically include a ‘back-up’ function, but for other models it is an option that will only be installed at an additional cost.

If you are not sure whether your solar battery has the ‘back-up’ function enabled, contact the RACV to organise a solar ‘health check’.

“If the need arose, and you have solar panels and a battery, you could store enough power by recharging daily to last theoretically for weeks,” Kieran adds. “But most black-outs only last an hour or two.”

Solar panels on the roof of a house

Solar vocabulary

Green energy

Green energy can generally refer to any power generated from a renewable and/or non-carbon producing source. There is an official GreenPower registration scheme in Australia that has some additional requirements, partially around when the generator was built as this affects whether it is considered to contribute to emission reductions or not.

Renewable energy

This refers to energy that is generated by renewable (or natural) sources, such as solar, wind, hydroelectric and geothermal power.

Clean Energy Council Solar Retailer Code of Conduct

This is a voluntary industry code, authorised by the ACCC, that is designed to lift quality higher than regulations require.

STC/LGC incentive scheme

Refers to the Clean Energy Regulator’s small-scale technology certificate (STC) and large-scale generation certificate (LGC). The Small-scale Renewable Energy Scheme creates a financial incentive for individuals and small businesses to install eligible small-scale renewable energy systems, such as solar-panel systems (and also small-scale wind and hydro systems, solar water heaters and air-source heat pumps). It does this through the creation of small-scale technology certificates which Renewable Energy Target liable entities have a legal obligation to buy and surrender to the Clean Energy Regulator on a quarterly basis. Small-scale technology certificates can be created following the installation of an eligible system, and are calculated based on the amount of electricity a system produces or replaces (that is, electricity from non-renewable sources).

Solar batteries

Usually referred to as home batteries, these are devices that are capable of storing power to be used at another time. In a solar application, this allows extra power produced during the day to be saved for later instead of being sent back to the grid. That way at night, the home can be powered from stored power that was generated from the panels rather than importing power from the grid (which would include non-renewable generation).

Solar optimiser

Solar optimisers are an optional accessory you can pay for when buying a solar system that helps to optimise the power output from each panel independently.

Reposit box

A controller for some home batteries that uses energy market data to identify times to export stored power directly to the grid when electrical spot prices are high.

Solar Feed-in Tariff (FiT)

The feed-in-tariff is a credit paid to households for excess energy that is sent back to the grid. This helps you ensure that excess solar energy produced by your panels is not going to waste and can help reduce your energy bills. As of 1 July 2019, the single-rate minimum feed-in tariff in Victoria is 12 cents per kilowatt hour (c/kWh).

Carbon offset

Carbon offset refers to the practice of reducing carbon emissions by an amount equivalent to emissions made in another activity. For example, I don’t want to contribute to global warming, but I need a car and can’t afford electric, so I work out how much carbon my car is producing and then pay to plant a number of trees that will capture the same amount of carbon from the atmosphere over their life as my car produces, thus offsetting the pollution. For more information visit Australia's Carbon Offset Project Registry.

Ready to go solar? RACV can help
Get a quote →