Is your solar battery blackout-proof?

Living Well | Peter Nugent | Posted on 08 October 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.

Power blackout at a house

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.” 


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