Glass that generates electricity

[voyager]

A fully transparent solar cell that could make every window and screen a power source. Researchers at Michigan State University have created a fully transparent solar concentrator, which could turn any window or sheet of glass (like your smartphone’s screen) into a photovoltaic solar cell. How about car glass is the first thing that came to mind?

A fully transparent solar cell that could make every window and screen a power source

 

[Ames]

Very impressive. Do you have any stats on power to area?

 

[FlasherZ]

Very impressive. Do you have any stats on power to area?

I think I saw the announcement about a year or two ago. From what I understand, the power is pretty minimal, but some power is greater than none.

Power-Generating Glass Windows Almost Ready For Market Breaking Energy - Energy industry news, analysis, and commentary
(from 2013)

I haven't found the original article I read, which had power numbers... I'll keep looking.

 

[Mookuh]

Very impressive. Do you have any stats on power to area?

From the article:

Michigan’s TLSC currently has an efficiency of around 1%, but they think 5% should be possible.

From my understanding, current Solar panels range anywhere between 15-22% in efficency, so at 1%, they are at 1/15th to 1/22nd of what normal panels can achieve, with the 5% figure improving that to a factor of 3-4. Using numbers from this very good piece on Solar efficiency, at 1% we're looking at around 0.05 kWh/day per square meter for a typical US location, maybe a bit less due to windows usually not being angled properly. That's not a lot, at 5% we're looking at 0.25 kWh/day per square meter, which sounds more useable but still low.

The kicker however is this: The amount of PV cells needed for this is actually fairly small, as it's just the small strips at the sides who are electrically active... the clear area merely diverts the non visible light to the sides of the window. So there is a realistic chance that this might actually be feasible, because even if the energy harvest is small, buildings are huge, and have a lot of windows... the useable surface area would be immense. (though only one/two sides of a building would work well, depending on facing.) It all depends on how expensive the material that makes up the bulk of this technology is, how difficult running the wires would be, how long the stuff lasts/how well you can clean it etc. Something to consider that with less energy delivered into the building by the sunlight, heating cost might rise slightly. Also the compability of these and widows to be opened is to be explored, though from what I understand, "cracking open a window" is not an option in huge 40-story office buildings.

Personally, I think the applications for smartphones etc. are limited, since you don't leave a phone out in the open enough to warrant a fancy screen like this...

 

[Carlios]

From the article:


From my understanding, current Solar panels range anywhere between 15-22% in efficency, so at 1%, they are at 1/15th to 1/22nd of what normal panels can achieve, with the 5% figure improving that to a factor of 3-4. Using numbers from this very good piece on Solar efficiency, at 1% we're looking at around 0.05 kWh/day per square meter for a typical US location, maybe a bit less due to windows usually not being angled properly. That's not a lot, at 5% we're looking at 0.25 kWh/day per square meter, which sounds more useable but still low.

Actually solar panels on houses and elsewhere usually have a bit lower efficiency. But in following years this might improve if somebody finds some new ways to increase efficiency. This is a new technology, give it couple of years to even see if anyone is mentioning it again. If it is, then efficiency might improve. There are probably ways where it'd be useful to use it.

 

[FlasherZ]

From my understanding, current Solar panels range anywhere between 15-22% in efficency, so at 1%, they are at 1/15th to 1/22nd of what normal panels can achieve, with the 5% figure improving that to a factor of 3-4. Using numbers from this very good piece on Solar efficiency, at 1% we're looking at around 0.05 kWh/day per square meter for a typical US location, maybe a bit less due to windows usually not being angled properly. That's not a lot, at 5% we're looking at 0.25 kWh/day per square meter, which sounds more useable but still low.

Well, not quite. That would be for roof glass. For the sides of buildings, not only do you have the efficiency loss, you have to deal with the 90 degree angle (for vertical windows).

 

[Mookuh]

Well, yes. My calculations were about the panel efficency, and I specifically said that the yield would be lower due to windows not being angled properly :smile:

 

[FlasherZ]

Well, yes. My calculations were about the panel efficency, and I specifically said that the yield would be lower due to windows not being angled properly :smile:

Perhaps your definition of "bit less" and mine are different for windows at 90 degree orientation.

 

[Mookuh]

Unable to provide proper numbers for this in a timely fashion, can I get out of this by claiming I meant in absolute terms, and since it's just gonna be a tiny bit harvested anyway, losing 50% or so due to bad angle makes you lose just "half a tiny bit"?

 

[ItsNotAboutTheMoney]

From the article:


From my understanding, current Solar panels range anywhere between 15-22% in efficency, so at 1%, they are at 1/15th to 1/22nd of what normal panels can achieve, with the 5% figure improving that to a factor of 3-4. Using numbers from this very good piece on Solar efficiency, at 1% we're looking at around 0.05 kWh/day per square meter for a typical US location, maybe a bit less due to windows usually not being angled properly. That's not a lot, at 5% we're looking at 0.25 kWh/day per square meter, which sounds more useable but still low.

The kicker however is this: The amount of PV cells needed for this is actually fairly small, as it's just the small strips at the sides who are electrically active... the clear area merely diverts the non visible light to the sides of the window. So there is a realistic chance that this might actually be feasible, because even if the energy harvest is small, buildings are huge, and have a lot of windows... the useable surface area would be immense. (though only one/two sides of a building would work well, depending on facing.) It all depends on how expensive the material that makes up the bulk of this technology is, how difficult running the wires would be, how long the stuff lasts/how well you can clean it etc. Something to consider that with less energy delivered into the building by the sunlight, heating cost might rise slightly. Also the compability of these and widows to be opened is to be explored, though from what I understand, "cracking open a window" is not an option in huge 40-story office buildings.

Personally, I think the applications for smartphones etc. are limited, since you don't leave a phone out in the open enough to warrant a fancy screen like this...

For a lot of places, buildings have more problems with _cooling_, especially when they're full of people. Also, there is value in filtering UV. Don't think the incremental cost would work out, but hey, research is good.

 

[FlasherZ]

Unable to provide proper numbers for this in a timely fashion, can I get out of this by claiming I meant in absolute terms, and since it's just gonna be a tiny bit harvested anyway, losing 50% or so due to bad angle makes you lose just "half a tiny bit"?

I was being a bit facetious anyway, so no worry. I did some very very very very very rough calculations and even larger buildings made of all-glass don't look so hot.

From a quick-n-dirty tool I've used before:

Where I am, it reports a 100 kWp array should generate approximately 162.8 MWh per year at optimal 39 degree tilt (fixed) and 180 deg orientation (due south) - as a reference. That same array at 90 degrees (vertical) facing due south will generate 102.9 MWh, due north only 18.6 MWh, and due east-west 75.8 MWh, according to the calculator. Assuming a building with equal coverage on all four faces, sitting square (0/90/180/270), the equivalent 100 kWp system (25 kWp on each side of the building), then, would then produce 68.3 MWh, for a loss of 58% due to orientation. Let's say you're going to optimize for the south-facing glass only - loss will be at 37%.

When I calculate the output for 1% and 5% efficiency for where I live (St. Louis) at optimal tilt vs. current 16% panels on my roof, I get .044 kWh/sqm/day for 1% & .223 kWh/sqm/day for my location for optimal tilt, so your calculations are close to mine. However, that 37% loss due to vertical orientation of glass is a big loss, that means for vertical glass buildings you're looking at .028 kWh/sqm/day (1%) and .140 kWh/sqm/day (5%).

On a 6 level (@ 4m per level) 100m x 100m glass building, you have 2,400 sq m of surface glass on the south side, or 336 kWh/day for the building @ 5% efficiency. At 15c/kWh, that's $50.40/day, or $18,396 per year offset. Let's not consider panel or inverter lifetime, etc., and just figure $18,396 per year for the IRS 39 year depreciation on office buildings, it's $717,444 over building lifetime in recovery/savings. There's probably other small puts/takes, but I'm guessing the marginal cost of the solar glass here is greater than that.

 

[Mookuh]

[...] it's $717,444 over building lifetime in recovery/savings. There's probably other small puts/takes, but I'm guessing the marginal cost of the solar glass here is greater than that.

Well, it doesn't seem to be "worth it" as the amount seems low. But on the other hand: 717,444$/ 2,400sqm = 298,93$/sqm. Unless my googling skills fail me, glass costs somewhere around 50$ per sqm, so the solar glass can cost around 6-7 times per square meter what regular glass costs and still be competetive.... however, *including* the costs for installation, and the solar panel strips. I imagine they would be somewhat cheap, but the wiring and installation would be the more restrictive cost factor.
At the end of the day, it may just barely break even (if that), and one might ask "why bother?". But we're still (hopefully) recuding CO² output and if it does break even, I ask: "Why not?"

 

[FlasherZ]

Well, it doesn't seem to be "worth it" as the amount seems low. But on the other hand: 717,444$/ 2,400sqm = 298,93$/sqm. Unless my googling skills fail me, glass costs somewhere around 50$ per sqm, so the solar glass can cost around 6-7 times per square meter what regular glass costs and still be competetive.... however, *including* the costs for installation, and the solar panel strips. I imagine they would be somewhat cheap, but the wiring and installation would be the more restrictive cost factor.
At the end of the day, it may just barely break even (if that), and one might ask "why bother?". But we're still (hopefully) recuding CO² output and if it does break even, I ask: "Why not?"

I get what you're saying, and if true then certainly why not. Lots of assumptions in these figures too, both + and -, so we'll have to let the industry generate a business case for it.

 

[Mookuh]

Indeed... I'm curious as to how expensive the process of treating the glass to make it work it's magic is, but I guess the numbers on that are not final yet. But to me the idea doesn't seem as inherently flawed as, say, putting solar panels underneath roads.

Also NotAboutTheMoney, you make a good point, especially considering that buildings considered for this kind of treatment are likely to be the ones in exposed locations that get a lot of solar irradiation to begin with.

 

[TheTalkingMule]

All these fancy solar applications like clear glass and solar roads/walkways really have no place until we're at 20% solar on the back of rooftop and utility scale installs. They're just too expensive and unnecessary.

 

[Mookuh]

All these fancy solar applications like clear glass and solar roads/walkways really have no place until we're at 20% solar on the back of rooftop and utility scale installs. They're just too expensive and unnecessary.

I respectfully disagree with that. Exploring new options shouldn't be delayed until the current ones are exhausted. And as said, whether this is worth it or not depends exactly on the cost factor. If it turnes out that the cost for this type of glass/solar arrangement beats the cost of regular glass, it should be used. That said, tall buildings would have to contest with being shadowed by other buildings nearby as well, unless they're single free-standing units, further limiting available area. Still, this strikes me as a better venture than the Solar Roadways and I wouldn't lump them in the same basket.

 

[voyager]

All these fancy solar applications like clear glass and solar roads/walkways really have no place until we're at 20% solar on the back of rooftop and utility scale installs. They're just too expensive and unnecessary.

Technology gets better, efficiency goes up, costs tend to go down. For new tall glass buildings it makes perfect sense. City governments may even declare them mandatory. I am curious how it may work out for car glass, which is tinted anyway... Despite its relatively low efficiency, it adds up when you leave your car parked outside in the middle of Death Valley...

 

[Mookuh]

I am curious how it may work out for car glass, which is tinted anyway... Despite its relatively low efficiency, it adds up when you leave your car parked outside in the middle of Death Valley...

Well... you don't park outside in the middle of DeathValley all too often, and that will also heat your car up immensely. The energy harvest would be fairly slim, and car glass has other pirorities (crash safety strikes me as highest on the list), not sure if you can treat carglass the same way. I'm not sure it's a useful application, only a very small step up from solar panels on the roof.