Case study: How solar PV is powering our Alexandra Canal depot – and beyond

Rooftop solar plus a state-of-the-art battery from Tesla have turned our Alexandra Canal depot into a green power plant for the neighbourhood. Here’s how.

Generating green energy and using it when the sun goes down

More than 1,600 solar panels sit atop the City of Sydney’s new Alexandra Canal depot, which opened in June 2018 and provides waste, maintenance and construction services for the southern city area. But rooftop solar isn’t the only green feature that sets the facility apart.

The depot is also home to a grid-scale Tesla Powerpack battery – the first to be installed and operational in the Sydney metropolitan area.

The battery can store up to 500 kilowatt hours of electricity, enough to meet the daily needs of about 50 homes in the City area and equivalent to the storage capacity of 50,000 mobile phone batteries.

The battery charges during the day from excess power produced by the solar panels, and the stored energy is used at the site after the sun goes down. Together, the battery and solar installation are helping the depot minimise its reliance on electricity from the grid.

Electricity transmission provider TransGrid installed the battery on the City’s behalf as part of an ongoing trial of customer-based energy storage. Put simply, that means TransGrid plans to support the local grid with the battery’s stored energy when demand is high, such as on hot summer days.

Giving back to the city

Transgrid has already begun making use of the stored energy, taking control of the battery in times of high demand and redistributing energy to other local buildings in the neighbourhood. This process – known as “demand management” – aims to reduce or defer the need for investment in new grid infrastructure, ultimately reducing the cost of electricity bills.

At the same time, the Alexandra Canal depot has begun contributing energy to the local grid because the site produces more than it uses, meaning it’s a net producer of energy.

The City of Sydney’s goal is for 50 per cent of all electricity in our local government area to come from renewables by 2030. The massive rooftop solar installation at the Alexandra Canal depot is a big boost for this plan.

Is a solar battery suitable for your home or business?

A growing number of Australian households and businesses are adding batteries to their rooftop solar setups. Here are the pros and cons of this developing technology.


  • A solar battery helps you get the best value from your solar panels by storing any excess electricity generated while the sun is shining

  • A battery makes you less reliant on the grid when the sun isn’t shining and can keep you powered up during blackouts.


  • Today’s solar batteries are expensive: based on current pricing, it takes about 20 years to recoup the cost of a rooftop solar setup plus battery. However, the technology is advancing quickly, which means batteries could be cheaper, smaller and more powerful in a few years’ time.
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