17 June 2014 — A world-first building-integrated photovoltaic-thermal roofing system – producing electricity and thermal energy – has been installed in Sydney by BlueScope Steel.
The roof, part of a $5 million project that received $2.3 million in funding from the Australian Renewable Energy Agency, or ARENA, combines pre-painted steel sheet roofing integrated with thin-film solar panels and a thermal duct system, which can provide warm or cool air to supplement airconditioning.
The system, which comprises two layers of steel with the top layer featuring the integrated solar panels, was installed on a rooftop of a renowned architect in Glebe completely replacing an old corrugated steel roof.
Dr Robert Scott, building and construction applications manager at BlueScope Steel, told The Fifth Estate the whole system took up 42 square metres, with 13 sq m of the roof including the building integrated PV panels, which have a capacity of around 1.4 kilowatts.
The thermal system produces an additional 3-6kW of thermal energy. It works by transferring heat absorbed by the top layer of steel or PV roofing to air flowing through the duct system beneath it, which can then be used to provide heat for the building.
“In winter the air could start off at, say, 15°C at the bottom of the roof and by the time it has passed up to the top it could be up to 20-25°C and able to be pumped straight into the house,” Dr Scott said.
At night, radiant cooling can remove heat from the building, effectively precooling it for the next day, which would be beneficial during hotter months.
What about the urban heat island effect?
As noted in a recent article, dark roofs are contributing to an increased urban heat island effect, and with BlueScope leading the charge in cool roof technology, does this thermal/PV system accentuate the problem?
According to Dr Scott, the heat generated by the roof is taken inside the building during cool months and when it isn’t needed, such as in summer, there is the option of having a venting solution to duct the heat directly out at the ridge of the roof.
Venting waste heat does not end up creating a micro heat island like would occur with a traditional black roof where the heat energy would be held across the whole roof.
“It’s something that we did analysis on to make sure we weren’t heading down one path [with cool roofs] and then killing it with PV thermal,” he told The Fifth Estate.
The waste heat could even have potential application in solar cooling systems, with BlueScope working with the CSIRO’s Dr Stephen White on desiccant cooling system technology.
- See our article Solar cooling heats up in Australia
“What we’re trying to do is capture energy for useful application,” Dr Scott said.
Path to commercialisation
The roof was unveiled on Friday by ARENA chief executive Ivor Frischknecht and Bob Baldwin, parliamentary secretary to the Minister for Industry.
Mr Frischknecht said the project was an important step towards commercialisation and cost competitiveness with conventional rooftop PV.
“This new integrated PV system has been designed to provide a low cost system for Australian residential, commercial and industrial rooftops,” he said.
“It has the potential to reduce installation and energy costs as well as reduce peak energy demands placed on the grid.”
Mr Baldwin said he believed BlueScope was well placed to take the technology through to commercialisation.
“This a great display of Australian ingenuity and an example of industry leveraging government funding to make breakthroughs that may lead to advanced manufacturing and export opportunities.”
ARENA, however, is set to be abolished by the federal government.
While the technological readiness of BIPV-T is in its late stages, Dr Scott said commercialisation hurdles are still material.
The company currently has another ARENA grant of around $500,000 to look at the “technoeconomics” of BIPV-T systems. In partnership with Germany’s Fraunhofer Institute and the Sustainable Buildings Research Centre at the University of Wollongong, BlueScope is developing a decision support tool to provide quantitative information around the expected outcomes from installing BIPV-T on existing Australian buildings.
The tool will help:
- building owners to understand the performance/cost savings from installing a BIPV-T system
- designers, builders and installers to identify the ideal design configurations of BIPV-T systems to ensure the best performance/cost savings for a wide range of climatic conditions and existing building types
- project partners to determine if BIPV-T systems offer a viable opportunity for further BIPV enhancements and cost reductions in retrofit circumstances
BlueScope is also working on a complementary BIPV-T integration project with the CRC for Low Carbon Living, which will cover the “back end” integration of the technology, tapping into the CRC’s engineering and built environment research knowledge.
The CRC is also working on addressing some of the issue with standards and codes around this type of product. The overall program aims to address the range of challenges needed to develop a commercially viable product that addresses regulatory, trades and cost barriers.