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Summary:

Startup EnFocus Engineering’s technology replaces an ordinary skylight with a high-tech version that features solar cells and optics to manage the light that flows into a room. The company will be installing a prototype system at Google.

DP on Roof w Background

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.

  1. This is a stunning technology! I Hope the cost of this kind of system will go down in the coming years.

  2. Not sure why this makes more sense than a skylight and separate solar panels.. This seems highly complex – none of the rooftop CPV companies have been successful for good reason. Google seems very interested in “cool” over “cheap and reliable”

    1. The concept certainly hasn’t been proven yet, and it’s good for any company to find a proper test site to see if the technology works. I also think it’d be remiss of us to view building-integrated PV simply with the same metrics as a regular PV system. Architects or building owners don’t spend money on designs and features just for saving money. But they do get some value out of those bells and whistles in other ways, however they measure it.

    2. In built community, PV is still too expensive. It’s not easy to realize how much power is consumed by commercial lighting and how little a PV panel can do. Here is an example that may help illustrate: a PV array rated at 1.5 kWp-DC optimally mounted on a roof in LA on a good summer day will only power 8 fluorescent fixtures of 2x40W for 10 hours to light up a 400 SF area. That’s achieved with one EnFocus panel with a size similar to a standard PV panel!

      Conventional skylight brings in daylight into the building. But the lighting level varies a great deal depending on the time of the day and the cloud movement. As a result, one has to keep half of the lights on all the time, limiting its ability to save power. Mixing skylight and PV will bring down the cost per kWH to a degree (because PV has a much higher $/kWH). This technology manages the sunlight all day long, using diffused sunlight that is cool and soft to produce better dispersed and more consistent lighting. Therefore, it delivers higher quality light and power at lower cost.

      Keep in mind, this technology actually leaves over 90% of roofspace for PV to make it easier to reach net zero. Hope it helps.

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