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Tallest building in U.S. will add vertical solar farm

By | March 22, 2011, 8:01 AM PDT

Chicago’s Willis Tower (formerly Sears Tower), North America’s tallest building, is already an icon in the city. But it could soon be an icon for solar energy use in cities?

A new project will take advantage of the tower’s vertical surface area by adding up to 2 MW of solar glass panels — equivalent to a 10 acre solar field — on the south side of the building’s 56th floor.

This pilot project will use photovoltaic glass units developed by Pythagoras Solar. From Inhabitat:

The new windows, dubbed high power density photovoltaic glass units (PVGU), are a clever hybrid technology that lays typical monocrystalline silicon solar cell horizontally between two layers of glass to form an individual tile. An internal plastic reflective prism directs angled sunlight onto the solar cells but allows diffuse daylight and horizontal light through. Think of it as a louvered shade which allows for views but cuts out the harsh direct sun.

If the project is successful, it could lead the way to other similar projects in cities. It’s a great way for cities to harvest energy without using up precious space in the city or limited rooftop space.

The product is also a potential breakthrough in energy efficiency in glass towers, where solar heat gain is the bane of energy-efficient design.

Photo: Odalaigh/Flickr

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Tyler Falk

About Tyler Falk

Tyler Falk is a contributing editor for SmartPlanet.

Tyler Falk

Tyler Falk

Contributing Editor, Cities

Tyler Falk is a Communications Fellow with Smart Growth America. Previously, he was an editorial assistant for Grist. He holds a degree from Goshen College. He is based in Washington, D.C.

Follow him on Twitter.

Tyler Falk

Tyler Falk

Tyler does not have financial holdings that would influence how or what he covers.

He writes for SmartPlanet and is not an employee of CBS.

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RE: Tallest building in U.S. will add vertical solar farm
This is the kind of development I want to see. 10 acres of land surface spared from solar farming, that can be used for something more beautiful to look at. Integration of energy sourcing on buildings and alongside certain roads, providing it is not too visually intrusive, is the way to go. However, all renewable energy sources rely on fossil fuel or nuclear to back them up. And it must not be forgotten that the earth is rotating so the sun's power is transient on any fixture for farming sunlight. There are real, irreducible limits to solar power.
Posted by Caroline Webb
23rd Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
@Caroline Webb

Well said.
Posted by Schleeve
23rd Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
too bad the solar cells like they use on the space station aren't available for us to use. the space station makes enough energy to supply 2700 homes and its cells aren't all that big. Something like that on the sears tower would really produce.
Posted by vrilman
23rd Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
Could you please explain how solar panels on one row of windows (the 56th floor), can displace a 10-acre solar field. That calculation seems several orders of magnitude off.
Posted by OPC1
23rd Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
Good question, OPCI. I am not able to do the calculations. I just went with the presentation by SmartPlanet. Your comment shows up the need for such articles to also include the calculations.

I am keen on the idea of reducing use of land surface that is needed for other purposes, especially the need for habitat by other species (all types). The invasion now about to be unleashed on the Mojave desert and adjoining areas to produce wind and solar power at an industrial scale is a tragedy of the first order. This kind of development that will cause extinctions, near extinctions, terrible visual blight, lots of harm to both ecosystems and to people living there, is proof to me that controls are needed on renewable power generation. It is like the old 'gold rush'. The whole situation is out of hand.

If renewables are confined to rooftop applications this will save the atmosphere from the wanton destruction of perfectly good carbon sinks, save majestic pristine eco-systems, save the lands from intensely ugly industrialization, and save the human soul from becoming totally alienated and empty.
Posted by Caroline Webb
23rd Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
#3, there is nothing that special about the solar cells on the International Space Station. They have the advantage of being outside of the Earth's atmosphere which means the sunlight striking them is considerably stronger than on the Earth's surface. And they only are shaded from the Sun for short periods as the ISS passes behind the Earth. In each 90 minute orbit they are out of the sunlight for perhaps 10 minutes.
Posted by riverat1
24th Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
#6. space station does 45 min light and 45 min dark every 90 min, for a total 12 hours light and 12 hours dark every day and the sunlight is less diffused, but the solar panels are FAR superior to what is on the market today available to the public
Posted by vrilman
24th Mar 2011
0 Votes
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RE: Tallest building in U.S. will add vertical solar farm
the space station does 45 min light and 45 min dark every 90 mins for a total of 12 hrs light and 12 hrs dark every day. It is true the sunlight is less diffused for them but the solar panels are FAR superior to what is on the market today available to the public
Posted by vrilman
24th Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
@OPC1 - I believe the comparison to a 10 acre solar field has to do
with the 2 MW of energy produced and not with the physical size of
the field. There isn't enough information on the article to say for
sure but one possible explanation would be that the 2 MW is
produced from a combination of direct energy captured by the panel
and the additional energy saved by reducing the solar gain, which in
turn reduces HVAC demand. Just a guess.
Posted by Gaoyou60
25th Mar 2011
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RE: Tallest building in U.S. will add vertical solar farm
@OPC1
You are quite correct. Good catch.

It would appear that Tyler cut back on a bit too much detail from
the original article, which states "that has the POTENTIAL [my
caps] to expand to a surface area allowing over two megawatts of
solar power generation".

It appears that the 56th floor deployment is a testbed.
Posted by inchman254
27th Mar 2011
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