The new self-powered version promises to be inexpensive and easy to apply to existing windows
The smart window controls the transmission of visible light and infrared heat into the building
The researchers chose the material because its chemical structure could be modified to absorb a narrow range of wavelengths
New York, July 2, 2017: By applying a new solar cell technology, researchers have developed a self-powered version of smart windows that could help save energy costs. Smart windows equipped with controllable glazing can augment lighting, cooling and heating systems by varying their tint, saving up to 40 percent in an average building’s energy costs. But these conventional smart windows require power for operation, so they are relatively complicated to install in existing buildings.
The new self-powered version promises to be inexpensive and easy to apply to existing windows, the researchers said.
This system features solar cells that selectively absorb near-ultraviolet (near-UV) light, so the new windows are completely self-powered.
“Sunlight is a mixture of electromagnetic radiation made up of near-UV rays, visible light, and infrared energy, or heat,” said Yueh-Lin (Lynn) Loo, Professor at Princeton University, New Jersey, US.
“We wanted the smart window to dynamically control the amount of natural light and heat that can come inside, saving on energy cost and making the space more comfortable,” she added.
The smart window controls the transmission of visible light and infrared heat into the building, while the new type of solar cell uses near-UV light to power the system.
“This new technology is actually smart management of the entire spectrum of sunlight,” Loo said.
In the paper published in Nature Energy, the researchers described how they used organic semiconductors — contorted hexabenzocoronene (cHBC) derivatives — for constructing the solar cells.
The researchers chose the material because its chemical structure could be modified to absorb a narrow range of wavelengths — in this case, near-UV light.
“Using near-UV light to power these windows means that the solar cells can be transparent and occupy the same footprint of the window without competing for the same spectral range or imposing aesthetic and design constraints,” Loo added.
The researchers explained that the near-UV solar cell technology can also power internet-of-things sensors and other low-power consumer products.
“It does not generate enough power for a car, but it can provide auxiliary power for smaller devices, for example, a fan to cool the car while it’s parked in the hot sun,” Loo said. (IANS)
When the worst floods in a century swept through India’s southern Kerala state in August, they killed more than 480 people and left behind more than $5 billion in damage.But one thing survived unscathed: India’s first floating solar panels, on one of the country’s largest water reservoirs.
As India grapples with wilder weather, surging demand for power and a goal to nearly quintuple the use of solar energy in just four years, “we are very much excited about floating solar,” said Shailesh K. Mishra, director of power systems at the government Solar Energy Corporation of India.
India is planning new large-scale installations of the technology on hydropower reservoirs and other water bodies in Tamil Nadu, Jharkhand and Uttarakhand states, and in the Lakshadweep islands, he told the Thomson Reuters Foundation.
“The cost is coming almost to the same level as ground solar, and then it will go (forward) very fast,” he predicted.
As countries move to swiftly scale up solar power, to meet growing demand for energy and to try to curb climate change, floating solar panels – installed on reservoirs or along coastal areas – are fast gaining popularity, particularly in Asia, experts say.
The panels – now in place from China to the Maldives to Britain – get around some of the biggest problems facing traditional solar farms, particularly a lack of available land, said Oliver Knight, a senior energy specialist with the World Bank.
“The water body is already there – you don’t need to go out and find it,” he said in a telephone interview.
And siting solar arrays on water – most cover up to 10 percent of a reservoir – can cut evaporation as well, a significant benefit in water-short places, Knight said.
Pakistan’s new government, for instance, is talking about using floating solar panels on water reservoirs near Karachi and Hyderabad, both to provide much-needed power and to curb water losses as climate change brings hotter temperatures and more evaporation, he said.
Solar arrays on hydropower dams also can take advantage of existing power transmission lines, and excess solar can be used to pump water, effectively storing it as hydropower potential.
China currently has the most of the 1.1 gigawatts of floating solar generating capacity now installed, according to the World Bank.
But the technology’s potential is much bigger – about 400 gigawatts, or about as much generating capacity as all the solar photovoltaic panels installed in the world through 2017, the bank said.
“If you covered 1 percent of manmade water bodies, you’re already looking at 400 gigawatts,” Knight said. “That’s very significant.”
Growing use of the technology has raised fears that it could block sun into reservoirs, affecting wildlife and ecosystems, or that electrical systems might not stand up to a watery environment – particularly in salty coastal waters.
But backers say that while environmental concerns need to be better studied, the relatively small amount of surface area covered by the panels – at least at the moment – doesn’t appear to create significant problems.
“People worried what will happen to fish, to water quality,” said India’s Mishra. “Now all that attention has gone.”
What may be more challenging is keeping panels working – and free of colonizing sea creatures – in corrosively salty coastal installations, which account for a relatively small percentage of total projects so far, noted Thomas Reindl of the Solar Energy Research Institute of Singapore.
He said he expects the technology will draw more investment “when durability and reliability has been proven in real world installations.”
Currently floating solar arrays cost about 18 percent more than traditional solar photovoltaic arrays, Knight said – but that cost is often offset by other lower costs.
“In many places one has to pay for land, for resettlement of people or preparing and leveling land and building roads,” he said. With floating solar, “you avoid quite a bit of that.”
Solar panels used on water, which cools them, also can produce about 5 percent more electricity, he said.
Mishra said that while, in his view, India has sufficient land for traditional solar installations, much of it is in remote areas inhospitable to agriculture, including deserts.
Putting solar panels on water, by comparison, cuts transmission costs by moving power generation closer to the people who need the energy, he said.