Central Melbourne could generate three-quarters of its power from solar panels, study suggests

12th November, 2021.      //   General Interest, Technology  // 

Solar panels in central Melbourne

Central Melbourne has the potential to generate three-quarters of its electricity needs from solar power, according to new modelling.

By integrating more solar panels into roofs, walls and windows, the City of Melbourne could generate 2,354 gigawatt hours of energy a year – equivalent to 74% of its current electricity consumption, the Monash University research suggests.

Prof Jacek Jasieniak, a co-author of the study, said the capacity of solar panels currently installed in central Melbourne was only a fraction of what was possible. “There’s a massive opportunity to build photovoltaics into a city, and Melbourne CBD … could be, as a collective, a distributed energy powerhouse,” he said.

The modelling focused on the City of Melbourne, a 37.4 sq km municipal area that includes the central business district, mid-rise developments in the inner-city suburbs of Carlton and South Yarra, and the industrial area of Port Melbourne.

Rooftop panels accounted for the vast majority – 88% – of the potential solar energy the area could generate.

Generating 2,354 gigawatt hours annually was “an ambitious target,” Jasieniak said. “That’s assuming that you’re getting pretty high-efficiency devices and you’re covering about 80% of the rooftops that are available.”

To produce that amount of energy, Jasieniak estimated several million solar panels would need to be installed in central Melbourne.

The researchers used 3D models that simulated how much sunlight would illuminate buildings during the day.

The modelling took into account seasonal variations in the direction of the sun, the shadows cast by buildings, and building properties such as rooftop space and window-to-wall ratios.

Jasieniak said the challenge was that many buildings have multiple tenants “and it’s not clear whose responsibility is it to ensure that there are maximised photovoltaics on those buildings”.

The study made calculations based on the efficiency of PERC photovoltaic cells, an existing rooftop solar technology developed by University of New South Wales researcher Martin Green.

It also assumed that solar panels would be integrated into building facades and windows, generating 8% and 4% of the calculated energy respectively.

“True building-integrated photovoltaics replaces the wall,” Jasieniak said. While the technology to do that exists, he said, “it hasn’t been done at scale” on buildings in Australia yet.

Solar windows – photovoltaic cells that generate energy but are transparent like glass – have been less commercially viable to date, because of their low efficiency of only 2% to 3%, Jasieniak said. “We’re working on technologies that increase efficiency by a factor of four or five.”

His research group Exciton Science is collaborating with the CSIRO to develop solar windows made of a crystal material known as perovskite.

Producing solar electricity close to where it is used minimises energy losses during transmission.

“It needs to be a distributed network,” Jasieniak said, meaning it is spread across the city.

He said there needs to be photovoltaics in fields to support areas where high density or solar integration was not possible. “You also want it to be in cities and in buildings.”

Future building design could take sunlight and shadowing into account to maximise the potential of solar power, Jasieniak said.

“In Melbourne, you could imagine that you could have slightly higher buildings towards the southern part of the city, so they can capture as much of that northerly sun as possible.”

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