Google plans to install a high-tech skylight that features solar cells and optics to manage the flow of light at one of its Silicon Valley office buildings in September. That technology is courtesy of startup EnFocus Engineering, and EnFocus founder and president Jason Lu tells us that Google will act as a test site for EnFocus’ prototype technology.
EnFocus, based in Hayward, Calif., has created a solar panel containing dozens of optical modules with lenses that concentrate and direct sunlight onto slivers of solar cells underneath to produce electricity. The optical system further directs and diffuses sunlight so that it floods into the room uniformly and creates ambient light, Lu said.
The ability to distribute the light evenly is a tricky task that many ordinary skylights can’t accomplish, Lu said. That’s why you sometimes get a brighter beam of light when you are underneath a conventional skylight. Such uneven disbursement isn’t typically a problem for a skylight at home, but it could be a concern at work, where employers don’t want certain parts of a room to shine brighter and feel warmer and cause discomfort for employees.
Google’s “primary intention is to have quality lighting for their engineers,” Lu said. “Saving electricity cost is only part of the payback. It’s more important for the employees to be more productive.” Google spokesman Parag Chokshi said the company likes to investigate and support new technologies, and that makes EnFocus a good candidate for doing a pilot project there.
The solar skylight
Each 100-pound EnFocus solar panel measures 53 inches by 44 inches by 8 inches and can produce up to 288 watts of power. The panels are encased in glass boxes to protect the components from environmental damage.
The panel sports a dual-axis tracker so that the optical modules will follow the sun’s movement throughout the day. The lenses concentrate the light 400 times onto cells made with gallium-arsenide and germanium, and that amount of concentration requires the use of direct sunlight.
Instead of tilting the entire panel to follow the sun, the tracker will tilt individual optical modules. An ideal installation would position the panel at an angle above the roofline to face south in order to get the maximum sun exposure, similar to the orientation of conventional solar panels on the rooftops.
Because the optical modules collect some of the light, they in effect reduce the amount of light and therefore the amount of heat entering the space below. That helps to cool the room and reduce the need to blast the air-conditioning system. Lu noted that some of the big skylights at airports often end up heating the space because they don’t do a good job of reflecting some of the light.
Embedded solar trend
The idea to design a system that generates solar electricity while also keeping out some of the heat is a popular one among companies. Several other startups, such as SolarOr and Pythagoras Solar, are putting solar technologies inside double-pane glass for windows or building facades. Architects and building owners who fancy using these high-tech windows and skylights will have to figure out how much energy and money savings they can really achieve with designs when electricity generation may not be the chief benefit.
Many of these startups are in the research and development stages and are setting up pilot projects to see if their systems perform as expected. Lu is looking to raise $3 million in venture capital for further development and to launch the technology into the market.
EnFocus was founded in 2004 to develop solid-state lighting, and it later switched focus to solar and won a $2.9 million research grant from the federal Solar America Initiative. The company also raised an undisclosed angel round of funding. A key investor is Inland Metal Industries, which also will fabricate and assemble EnFocus’ prototype systems.
The pilot project at Google will be crucial for EnFocus to prove its technology. Its panel design contains more moving parts than conventional solar panels, so making sure the mechanical components work well for many years is one of the challenges, noted Daniel Friedman, the manager of the concentrating photovoltaic group at the National Renewable Energy Laboratory.