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Chicago's Willis Tower (formerly the Sears Tower) is America's tallest skyscraper. It will soon receive a solar makeover, making it the nation's largest vertical solar farm.  (Source: Ted Hubert)

The solar panels (artist's concept) will preserve the view, but reduce glare and generate electricity. The installation is expected to produce up to 2 megawatts of power when complete.  (Source: Pythagoras Solar)

Pythagoras Solar's special window design uses prisms to collect direct sunlight will allowing horizontal and diffuse sunlight to pass through, lighting the room.  (Source: Pythagoras Solar)

The actual product is seen here at an industry trade show.  (Source: Pythagoras Solar)
Project will be nation's largest solar farm

Alternative energy startup Pythagoras Solar is dreaming big and it has sold the owners of one of America's most iconic skyscrapers on its vision.

Chicago's Willis Tower (formerly known as the Sears Tower) is among the most recognizable man-made landmarks in the country.  Towering over local high-rises, its 108 stories make it the tallest building in the U.S. and the fifth-tallest freestanding structure in the world.

During summer months solar heating contributes to energy costs and sun glare can be an issue at times.

Pythagoras Solar power has cooked up a novel solution -- transforming the building into the nation's largest vertical solar farm.  The farm will produce up to 2 MW of solar energy, reducing the building's reliance on the power grid.

Its panels -- to be installed on the building's southern-facing windows that get the highest sun exposure -- will help remedy both issues, while preserving the view and producing electricity.

The company's pane design is dubbed high-density photovoltaic glass units (HD-PVGUs).  The device acts similar to louvered windows (think slat blinds).  It contains a thin layer of monocrystalline silicon, sandwiched between glass, which acts as a cell.  An internal plastic prism directs angled (direct) sunlight onto the cell, while allowing diffuse daylight and horizontal (less intense) sunlight through.

The result is that you still have attractive views out the window, without the glare or heating.  Meanwhile your panel produces electricity that Pythagoras Solar claims is on par with rooftop panels.  

If the installation is a success, it could set a precedent for high-rises across America.  The Willis Tower installation alone is expected to produce as much power as a 10-acre ground installation would.

Conserving land, particularly in a city, is obviously a tremendous concern.  The Willis Tower project could serve as a blueprint for skyscraper owners to reduce their energy costs and improve their buildings' sustainability in years to come.

Cost and maintainability are obvious concerns in the long run for solar window panels from companies like Pythagoras Power.  Indeed, Pythagoras Power offered little insight into how it would handle the extra maintenance burden or what the cost-per-window might be.  

That said, even if the company did provide such metrics, it'd be hard to fairly judge them, as this project is the first of its kind on this kind of magnitude.  Initial implementations of any technology typically start off high in terms of maintainability problems and cost, but eventually bring down both metrics.  

And the cost must not be overly exorbitant.  After all, the panels are good PR for the Willis Tower's owners, but they are in business to make money.  If the panels were overly expensive, the project likely wouldn't have received the green light to begin.

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RE: Makes sense
By deathwombat on 3/22/2011 2:17:41 PM , Rating: 5
2 MW is nothing to sneeze at. That's enough to power 80,000 25 W fluorescent lights -- 740 lights per floor, which is probably pretty close to how many lights the tower has.

Alternatively, it's enough power to run 10,000 workstations @ 200W/computer. There are probably more computers than that in the building, but it's still a good start.

It's probably enough to power 2000 laser printers (20 per floor) or 1000 photocopiers. I mean, yes, it's a drop in the bucket when you consider the total power consumption of a building that size, but if I came up with a way to produce enough power to run every light in the building, or most of the computers, or half of the printers, most people would be impressed with that.

Also, remember that the farther you are from the equator, the longer the days get in the summer, when electricity demand spikes due to air conditioners. The cooling requirements of a building that size are enormous. Most of the heat is coming from printers and photocopiers and body heat, but sunlight definitely contributes to those needs, and a panel that captures or reflects some of that light would measurably reduce the building's cooling costs, and take up to 2 MW off of the grid during the period of peak demand. 2 MW could reduce the local incidences of brownouts and rolling blackouts.

RE: Makes sense
By quiksilvr on 3/22/2011 3:45:16 PM , Rating: 2
2 MW is nothing to sneeze at if they keep the price realistic and maintenance costs down. Otherwise it isn't worth it.

RE: Makes sense
By bah12 on 3/22/2011 5:48:08 PM , Rating: 2
Correct, listing the number or random electrical devices it can run is irrelevant. 2MW is 2MW it will either pay or not, and as long as my tax dollar is not funding it (as usual) then kudos for doing it.

RE: Makes sense
By callmeroy on 3/23/2011 3:25:28 PM , Rating: 2

Seems like a cool project to me - if people are serious about this solar panel thing ever kicking off you need a major "test bed" project like this to happen anyway.

....just don't use tax dollars for it.

RE: Makes sense
By Keeir on 3/22/2011 7:16:10 PM , Rating: 2
2 MW is nothing to sneeze at.

Errr... Power DNE Energy. A 2 MW peak solar installation will likely only net around 3-6 MWh a day. In other words... its likely to only light those flourescent lights for 2-3 hours a day max.

Maybe this vertical solar farm will be different, but other types of installed solar have very low avaliblity rates for the power genetation.

I am going to say that they may save more on cooling costs than the save on the electricity produced.

RE: Makes sense
By bobsmith1492 on 3/22/2011 10:38:43 PM , Rating: 2
Conversely, as this is Chicago after all, they may lose more on heating costs than they gain in electricity costs...

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