
Turning windows into powerplants - ph0rque
http://web.mit.edu/newsoffice/2011/transparent-solar-windows-0415.html
======
ph0rque
What would be really interesting is if you could tune how much IR (edit: near-
IR, actually) light goes through, and how much gets absorbed... that way you
get solar heating when needed.

Edit: thinking more about it, why not have the whole visible spectrum be
tunable, so that you can create window blinds any time you want them, and
increase energy production in the process?

~~~
simpleTruth
First off, normal glass also blocks IR light (which is a good thing) when the
outside produces more IR light you want to cool the inside, and when it's
producing less you want to heat the inside.

Anyway, the energy from sunlight is for the most part visible light so you
can't really use most of the energy without also blocking visible light. The
best option is automatic shades which make the outside look dimmer but don't
totally block the view.

~~~
ph0rque
The journal article linked to in the article
([http://apl.aip.org/resource/1/applab/v98/i11/p113305_s1?bypa...](http://apl.aip.org/resource/1/applab/v98/i11/p113305_s1?bypassSSO=1))
mentions near-IR absorption.

~~~
simpleTruth
It's an interesting idea, I am simply mentioning the practical limitations.

At this point it's a question of how cheaply they can scale it up and how much
you can improve the efficiency. Looking at some of their numbers they block
~30+% of the light to gain ~1.3% of the energy you are better off with smaller
windows and a high efficiency solar cell around the window. AKA 10% smaller
windows block 10% of the light + a 20% efficient solar cell = 2% efficiency.
Granted, there is probably a market even in it's current state.

~~~
gamble
I think the news article exaggerates the purpose of the device described in
the actual paper. It isn't intended as a competitor for opaque power
generation cells. The idea is that, since you already need an anti-reflective
coating to block IR light, it might as well be a coating that can scavenge a
bit of the incident power instead of sending it all back into space.

------
lutorm
This seems a bit weird. They claim that they think they will reach an
efficiency of 12%, like normal solar cells, but that's of course neglecting
the fact that only a fraction (max half) of the sunlight is in the IR. So the
amount of energy you'd get is still only half (not that that is
insignificant).

~~~
T_S_
If that's true then regular solar cells only get a shot a half the energy too.
So it doesn't seem so weird to me.

More weird to me, after spending some time in the business, is all these
solutions which only require "some engineering" are perpetually around the
corner. People, stop taking "some engineering" or granted! :)

~~~
lutorm
Well, it depends on what you mean by efficiency. I would say that if I say "I
have these solar cells that take sunlight and create electricity with 12%
efficiency", I would expect that I get 12% of the total insolation in
electricity. If I instead say "these solar cells take infrared sunlight and
create electricity with 12% efficiency", then I expect it to be 12% of the
_infrared_ sunlight, not 12% of the total sunlight. It depends on what the
hypothetical "fully efficient" case is.

------
PandaPacha
Besides of windows, one of the first real-world applications of this
technology might be in our smartphones in order to gain in battery life.
That's what WYSIPS ( <http://www.wysips.com/> ) has planned to do with their
similar technology. And they seem a bit ahead.

------
brianbreslin
I find this fascinating. Slightly off topic, but do you think we'll see in
10-20 years most new buildings generating a significant % of their energy
independently (their own solar, geothermal, waste re-use)?

~~~
khafra
In Germany, Zero-Energy Building is already popular:
<http://en.wikipedia.org/wiki/Zero-energy_building>

------
prewett
I stopped reading when they said it is only 1.7% efficient but expect it to
get up to 12%. That's almost an order of magnitude! It seems unlikely that
their prototypes are so bad that they can get an order of magnitude
improvement easily. And if it takes years of work to get to 12%, well,
everybody else is claiming great performance in the nebulous future, too.

~~~
melling
Considering that you currently get 0%, that's not bad. If the cost is low
enough and people could reduce they're electric bill by a small amount why not
dual-purpose your windows? It might even pay for the upgrade over ten years.

