Solar skyscraper – pv magazine India

Since pv magazine 05/2022

The heart of Melbourne’s downtown, Australia, is known for many things: “Instagrammable” little alleyways of graffiti, trendy cafes, trams, museums, and of course, its cluster of skyscrapers popping up out of nowhere like the emerald city of oz. But what those walking the streets of downtown Melbourne can’t see 145 meters above their heads is that there are 500 Trina Solar modules operating as a 223kW system at the top. of Towers 1, 2 and 4 of Walker Corp’s Collins Square Tower site.

Putting solar panels on the roofs is hardly worthy of interest; in fact, Australia is the world leader in rooftop solar installation. But putting solar power on top of skyscrapers isn’t that common, partly because the generation profile wasn’t worth it. After all, the beauty of tall buildings is that the roof is only a tiny fraction of the total square footage of the structure.

However, with recent advances in the energy density of solar panels, this profile has changed. Recognizing this, Walker Corp., one of Australia’s largest private development companies, has partnered with Venergy Australia to supply the SolarEdge optimized solar system to its Collins Square Tower development.

“With advances in solar technology, the high energy density panels now available exceed 450W per panel, enabling large and meaningful renewable projects in CBD sites that could not otherwise be done on the constrained rooftop,” said Matthew Wilkins, CEO of Venergy Australia.

Venergy has integrated the 223 kW solar system with the building’s regenerative elevators and its 600 kW gas turbine trigeneration on five commercial towers, bringing the site’s total generating capacity to 2 MW.

Cameron Forbes, director of engineering and sustainability for Walker Corp., said photo magazine that the company strives to ensure its towers are equipped with “advanced solar technology” that can be fully integrated with “our existing energy monitoring and management systems, allowing our team to track the performance of the panels at all times”.

two for tango

The Collins Square Tower solar configuration isn’t the only sky-scraping solar array in the city. In fact, Cbus Property announced in November 2021 that it planned to coat a A$1 billion ($720.5 million) retail office tower in Melbourne’s central business district with a ‘solar skin’. capable of generating 20% ​​of the electricity needs of the base building of the project. .

Looking at these two projects, we see two different ways to integrate solar power into high-rise buildings: rooftop solar and building-integrated PV (BIPV). But by combining the two, we may be looking at the future of energy-integrated construction in vertical cities, namely the combination of two generations integrating both energy-dense roof panels and BIPV.

This combo is precisely what the ARC Center of Excellence in Exciton Science, based at Monash University, found, in collaboration with the University of Lisbon. Researchers modeled in 3D the viability and impact of window-integrated photovoltaics alongside other city-scale solar technologies. Published in the journal Solar Energy, the study found that buildings in Melbourne could supply 74% of their own electricity needs if solar technology was fully integrated into roofs, walls and windows. Rooftop solar would make up 88% of this supply, with wall and window embedded solar providing 8% and 4% respectively.

The research team, including study co-author Professor Jacek Jasieniak, examined 37.4 square kilometers (m²) of central Melbourne, of which 35.1 m² were residential and commercial buildings in 2019 They then determined the annual solar irradiance on building surfaces in Melbourne. identify suitable areas for PV, considering cost factors, technical limitations, shading and shadows. And at city scale – including warehouse-sized rooftops in city environs such as ports and stadiums, such as Melbourne’s famous cricket ground – the capacity potential of rooftops is amazing.

“Our goal was to show that there is actually huge potential (for urban PV, especially on rooftops), it’s just huge,” Jasieniak said. “But people don’t think about it because they tend to think at the scale of a building rather than the scale of a city.”

“As the technology evolves, what we will find is that the additional costs to add the photovoltaic components to the buildings is going to make the value proposition for the integration very strong,” continued Jasieniak. “Our driving force for this study was to understand the desirability of window-integrated solar cells, and what came out of the study was that actually for most buildings, the roof is very attractive. is the handy fruit there.

But Jasieniak notes that the primacy on roofs will remain the case as long as walls and windows (BIPV) still require a technological revolution. Compared to the roof, the cost of a solar window is “an order of magnitude more than what you would pay for a solar cell on a roof”.

However, noted the study’s co-author, “if your building costs you, say, AUD 1 billion, and you spend AUD 40 million on solar cells that, over their lifetime, will bring electricity is the important part to consider. The initial cost is not the driving force, it should always be the levelized cost of electricity. It is always a matter of the payback period, it does not won’t be seven years, but does it really have to be in a commercial building that will last at least 40 years? I don’t think so.”

Jim Stewart, associate director at Fender Katsalidis – the Australian architectural firm behind the world’s second tallest building, Kuala Lumpur’s 678.9m Merdeka 118 (p. 50), topped with a 140kW solar panel for its Park Hyatt Kuala Lumpur hotel – said photo magazine that customers are encouraged to consider photovoltaic solutions, as “most buildings over 180 meters high are not demolished within 50 years”.

“Rooftop solar panels have become commonplace in skyscraper design and development,” Stewart continued. “And, in the Australian context, their economic viability has been proven and accepted. However, space is always limited, so ever-increasing densities allow us to go further in terms of design flexibility and system capacity. In the context of high-rise development, PV is a mature and affordable technology with the ability to power building services and reduce peak loads on the grid; an “obviousness” indeed. »

Main challenges

The potential of PV in vertical cities comes with challenges. First, most PV installations would be brownfield retrofits on existing rooftops, which can be problematic, as high-rise buildings often already have other infrastructure.

Another challenge is that high-rise buildings tend to be leased, making it difficult to clarify responsibility and the direct benefits of PV. “But there’s a value proposition in there,” Jasieniak argued. “There has been a shift in business sentiment – ​​companies are now demanding 10 star building requirements, and at that level you need onsite power generation.”

But manufacturers are also required to change and support the integration of PV. “A lot of these construction companies are doing what they’ve been doing for a long time,” Jasieniak explained. “Innovation in building practices is needed to support large-scale construction.”

Nonetheless, Jasieniak sees a future where high-rise buildings are fitted with rooftop photovoltaic panels, with BIPVs further down the line, and possibly net-zero carbon buildings. Before that, he says there are tough questions in terms of policy and value shifts in individual companies and for developers and builders in terms of PV integration. “I think there’s an opportunity here for market segmentation as well.”

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