An energy-producing window
24 Aug 2011
GE likes Pythagoras Solar’s photovoltaic glass unit, which generates power for office buildings while letting natural light stream in.
The world’s first transparent photovoltaic window
By Desmond Bentley
GE doesn’t hand out awards easily. So when Pythagoras Solar beat out nearly 5,000 entrants to win this year’s $100,000 GE Ecomagination Challenge – which recognizes the most promising green energy building innovations – architects took notice.
The Israeli company’s unique solar window is the world’s first transparent photovoltaic glass unit (PVGU), which can make the much-vaunted vision of a net zero-energy building possible."Innovative optics using solar cells will allow solar energy to become part of the next generation of building design," says Pythagoras Solar CEO Gonen Fink. "This will produce benefits such as power generation and reducing the building’s energy needs, while allowing light in."
The product can be adapted to existing buildings, he says. "Retrofitting an office block with our windows can pay back the investment in five years. It’s also aesthetic, which makes the whole concept more attractive to architects."
Window into growing market
Fink founded Pythagoras four and a half years ago together with Dr. Italy Barouche, an expert in neuronal networks. He was previously instrumental in turning fledgling start-up Check Point Software Technologies into a multi-billion-dollar global market leader in Internet security.
"We were working with a group of people looking for added advantages to solar cells and the best applications for solar energy," he recalls. "We decided to concentrate on commercial buildings, working with the market and getting feedback. We started with the question: What does the world need in order to adapt this technology?" After all, he points out, solar energy is ubiquitous.
"The market for solar cells is maturing. I think people underestimate the revolution that’s taking place in the construction industry. There will be other companies in this market, but while many companies are coming up with solutions to reduce energy consumption, this only solves part of the equation."
The issue of commercial buildings’ energy efficiency is becoming increasingly important worldwide, with more stringent legislation in many countries aimed at lowering energy consumption. According to the United States Department of Energy, building operations account for up to 39 percent of the country’s energy consumption and 70% of its power plant-generated electricity. More than 30% of this energy is lost through poor building efficiency.
"The Obama administration has just set new energy reduction targets. Many people have yet to internalize the magnitude of this revolution," says Fink. "New commercial buildings will now include power generation and energy efficiency. The construction industry now has greater understanding of the needs, and huge progress has been made in recent years."
Coming up with a breakthrough technology is one thing. Getting the end-user to like it is another. The photovoltaic windows were successfully tested last year in a series of pilot projects in commercial buildings in Israel and the US, including the Sears Tower in Chicago. "We took existing buildings and showed that it works. Then we went to the next stage, which is commercial installation and expanding our manufacturing capacity," says Fink.
Architects, he says, are particularly excited about the new option the product offers. "The high transparency makes for aesthetically pleasing building designs. This process is not something that happens overnight – it can take six months or more to install, and it takes a year or two from design to actual implementation."
This particular product is less suitable for residential use, he explains, because in relative terms, private homes have far fewer windows. "The current method of placing solar panels on roofs is limited – it’s too expensive and has only one use," says Fink, noting that the price of the core ingredient, silicon, is high worldwide. "A significant part of the cost is for labor – it’s expensive to put them on the roof. Also, solar panels need a lot of surface area."
Let the sunshine in
Studies have shown that office workers prefer daylight. Standard windows let in harsh sunlight and heat, which means enormous air-conditioning costs. Blocking windows with curtains or blinds increases the need for artificial lighting. Pythagoras’ optical design uses direct light to generate energy, while optimizing daylight inside the building.
"The idea is to maintain the work environment at a comfortable temperature without massive energy-guzzling cooling and heating systems. There’s a lot of room for this idea to continue to grow, by integrating it into building design. Imagine a commercial facade. If you could replace the glass with glass that can improve energy efficiency, the advantages are multiple."
While the company’s R&D center is in Israel, Pythagoras Solar is now based in Silicon Valley, while much of production takes place in Los Angeles. "This company is about to take off," says Fink. His optimism appears justified. "Until now, the term ‘green building’ has been all about reducing energy consumption. This is the first time we can bring power generation into the equation. Ours is the first product that actually combines both aspects."