Published on July 12th, 2010 | by Susan Kraemer2
Pythagoras Makes Skylights that Also Make Solar Power
The unusual (philosophy M.A.) founder of Pythagoras Solar, Gonen Fink will be among the speakers at Intersolar 2010 in San Francisco this week. His start-up has designed a nearly transparent, yet fully solar glass using patent-pending optics, for use as an energy efficient skylight (and starting next year, a window wall) that also produces electricity.
Just the thermal efficiency alone would make it a good day-lighting option, blocking all direct solar radiation, to reduce building heating and cooling costs.
It is ideal for use as a skylight because it also provides better day-lighting compared to other BIPV or building-integrated photovoltaics (being essentially transparent), limiting lighting costs by replacing fluorescent lighting while looking like a regular skylight that provides real natural daylight.
But the real clincher is that it produces solar power more like that of regular solar panels, at 13 watts a square foot, than the usual building-integrated PV (BIPV).
Usually BIPV takes a trade-off for the aesthetic appeal, in less electricity produced per square foot (efficiency) than regular PV.
But at 13 watts a square foot, two ten foot by ten foot skylights, amounting to 200 square feet, would comprise a 2.6 KW solar system which on average could produce around 500 kilowatt hours a month, depending on variables like the region’s insolation, shading etc., but obviously more than a dumb skylight.
This makes it particularly suitable for single storey strip malls, now typically lit by ugly fluorescent strips. A skylight positioned to center over each store on a single story commercial building, would bring much needed daylight into a cavernous space, while producing enough energy to supply the store some or all of its electricity as well.
The dual use is achieved with optics on the surface that filter light to let daylight through, while mirrors reflect light onto solar cells. Typical commercial insulated glass units have two panes of glass, placed about one inch apart and held in a metal frame, which are coated with a film to block out heat from the sun.
Pythagoras Solar’s glass unit also uses two panes but the glass unit is made of several tiles, each of which has a solar cell to generate electricity with traditional and extremely efficient monocrystalline silicon cells from Chinese partner China Sunergy.
Pythagoras Solar’s first product, due in the third quarter this year, will be a skylight but the company also plans to make curtain walls for new buildings. Payback is looking like about five years, but of course each case is different as it depends on the regional cost of the utility electricity that it would replace.
The company boasts some outside-the-box thinkers. Chief Technical Officer Itay Baruchi is a physicist whose work on biological memory – a key to eventually producing neuro-memory chips – was cited by Scientific American as one of the 50 most significant scientific breakthroughs in 2007.
CEO and co-founder Gonen Fink, with a B.Sc in physics and computer science, was vice-president of R&D of the Israeli Internet security company that invented the firewall (Check Point), and is a graduate of one of the IDF’s elite IT units. (But he also found time to do an M.A. in philosophy – that may be behind the name Pythagoras.)
Their unusual IT background has resulted in an interdisciplinary breakthrough configuration that combines existing technologies, such as the traditional cells, and multilayer glass for efficiency, and traditional concentrating solar technology (but employed at the miniature level within the glass) rather than trying any one entirely new technology.
“Our approach is based on proven technology and existing form factors more than some of the new systems, but we use innovation in optics, semiconductor and mass manufacturing processes to significantly reduce the cost of materials being consumed,” is how CEO Gonen Fink describes it.