Glass Buildings May Turn Into Solar Power Plants

Do we have to start liking them?

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Yongxi Li holds up a sample of a transparent solar cell.
Yongxi Li holds up a sample of a transparent solar cell.

 Robert Coelius, Michigan Engineering Communications & Marketing

Treehugger has never been fond of glass towers, even calling them "energy vampires." Others see through a different window and envision them as power sources. Now researchers at the University of Michigan have developed an organic photovoltaic (OPV) applied to window glazing that has a remarkable 8.1% efficiency and 43% transparency with only a slight green tint, "more like the gray of sunglasses and automobile windows."

Yongxi Li holds up vials containing the polymers
Yongxi Li holds up vials containing the polymers. Robert Coelius, Michigan Engineering Communications & Marketing

Organic solar cells have been the future of photovoltaics for a while now; they are basically organic chemicals printed on plastic. The problem has been that they were way less efficient and didn't last nearly as long, five years compared to the 25 years of the estimated life of a silicon solar panel because they break down under exposure to moisture and oxygen. Other researchers have figured out how to deal with the degradation problems, and now research scientist Yongxi Li claims to "balance multiple trade-offs to provide good sunlight absorption, high voltage, high current, low resistance and color-neutral transparency all at the same time."

The new material is a combination of organic molecules engineered to be transparent in the visible and absorbing in the near infrared, an invisible part of the spectrum that accounts for much of the energy in sunlight. In addition, the researchers developed optical coatings to boost both power generated from infrared light and transparency in the visible range—two qualities that are usually in competition with one another.

A few years ago, when writing about an earlier attempt at power windows, I complained that this was a silly idea; that the best window isn't as good as the worst wall, that glazing shouldn't be more than 40% of a wall, and that we would be better off covering the 60% of solid wall with 20% efficient silicon panels instead of spending more to get 3% to 5% out of the windows. I also railed against all-glass buildings, calling them a thermal and aesthetic crime, quoting Chicago architectural critic Blair Kamin:

To be sure, glass signals modernity, its transparency is irresistible to those who crave panoramic views, and it tends to be cheaper than masonry. Yet is there no room for materials that last longer, have more character and are more energy-efficient?

But what happens when that glass is absorbing all that infrared energy that overheats glass buildings and turning it into electricity? Or if the transparent solar panel is in double, triple, or vacuum glass? Witold Rybczynski complained also about all-glass buildings:

The problem with transparent glass is that it doesn’t hold a shadow, and without a shadow there can be no “play of volumes.” Since minimalist modernist architecture doesn’t offer decoration or ornament, that doesn’t leave much to look at.

But if the glass is generating electricity, you don't want a shadow. You want as much flat surface area as possible.

There are many reasons to dislike all-glass buildings. Marine Sanchez of RDH Building Science has explained how they are not sensible for working or living.

Talk to the occupants, as opposed to the people designing the space. An entire glass facade is not what people are after. If you’re in an office and there’s glare the entire day, then these are not adequate conditions. Privacy, if it’s your bedroom, it’s open everywhere to all the neighbors. Or if you’re at work, wearing a skirt and everybody can see you.
Hudson Yards from the High Line
Hudson Yards from the High Line. Lloyd Alter 

Just this week I was talking to a building consultant who wanted to start a sort of @mcmansionhell twitter feed for all-glass buildings, to embarrass architects who continue to design these "thermal and aesthetic crimes."

But I wonder if our story has to change if they are energy providers instead of vampires, if it is is a high-quality window, tuned to filter out the heat, and is actually an effective solar panel generating useful amounts of electricity.