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Solar panels disguised as terracotta tiles in Pompeii

theartnewspaper.com

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Re: Solar panels disguised as terracotta tiles in Pompeii

#11

Post by bryanlarsen »

causi wrote: post #6

They can be designed to appear like stone, wood, concrete or brick, so can be hidden on walls and floors, as well as on roofs, Somebody wanna run the numbers and tell me how many decades it will take for one of these things to offset its manufacturing & installation carbon footprint? I'm betting it's a while.

The answer for traditional solar panels is about 2 months IIRC.

The answer for these should be significantly less, because you should only count the delta between solar tiles and non-solar tiles rather than the entire footprint.

Re: Solar panels disguised as terracotta tiles in Pompeii

#12

Post by isoprophlex »

xg15 wrote: post #4
mgerdts wrote: post #2

The company that makes them: https://www.dyaqua.it/invisiblesolar/_en/

> Inside the module there are incorporated standard monocrystalline silicon cells. The surface, that is opaque at the sight but translucent to sun rays, allows the light to enter and feed the cells. When they talk about "sun rays", do they mean the UV portion of sunlight? Because if the material were transparent to visible light, it would be, well, transparent, wouldn't it?

Monocrystalline Si has a 1.2 eV band gap iirc, meaning it absorbs everything smaller (more energetic) than ~ 1100 nm.

Our eyes see, what, 200-600 nm? Removing the 200-600 nm bit leaves you with approx 50% of the energy left between 600 and 1100 nm, glancing at [1]

This is all VERY back of the envelope... but I think these lose around half of the energy you'd get out of conventional panels.

[1] https://www.researchgate.net/publication/303914764/figure/do...

Re: Solar panels disguised as terracotta tiles in Pompeii

#13

Post by serf »

TeMPOraL wrote: post #9
serf wrote: post #8

Earlier quoted context omitted.

I guess that doesn't matter much as long as it pushes customers who would have never otherwise used such things to do so at all. in other words, for historical sites or places where aesthetic matters a lot , the conversation is "should we use these less efficient panels that fulfill our aesthetic requirements, or should we forego the use of solar all together?"

If EROI on those panels is negative then it's better to forgo them.

I agree -- but the picture is often more complicated for places that rely heavily on tourism and marketing.

The image portrayed by a tourist destination that is making large efforts towards 'green initatives' may be a more enticing sell to the increasing number of 'eco-tourists', many of which have never thought a day in their life about EROI.

Re: Solar panels disguised as terracotta tiles in Pompeii

#15

Post by scythe »

isoprophlex wrote: post #12
xg15 wrote: post #4

Earlier quoted context omitted.

> Inside the module there are incorporated standard monocrystalline silicon cells. The surface, that is opaque at the sight but translucent to sun rays, allows the light to enter and feed the cells. When they talk about "sun rays", do they mean the UV portion of sunlight? Because if the material were transparent to visible light, it would be, well, transparent, wouldn't it?

Monocrystalline Si has a 1.2 eV band gap iirc, meaning it absorbs everything smaller (more energetic) than ~ 1100 nm. Our eyes see, what, 200-600 nm? Removing the 200-600 nm bit leaves you with approx 50% of the energy left between 600 and 1100 nm, glancing at [1] This is all VERY back of the envelope... but I think these lose around half of the energy you'd get out of conventional panels. [1] https://www.researchgat…

Human visual range is generally 400-700 nm, although some small responsiveness remains up to 800 nm and down to 360. Below 400 nm is usually considered ionizing radiation.

But even a ~20% reflection coefficient can make something appear "opaque" if viewed in sunlight and complete darkness behind it.

Re: Solar panels disguised as terracotta tiles in Pompeii

#16

Post by teruakohatu »

bryanlarsen wrote: post #11
causi wrote: post #6

They can be designed to appear like stone, wood, concrete or brick, so can be hidden on walls and floors, as well as on roofs, Somebody wanna run the numbers and tell me how many decades it will take for one of these things to offset its manufacturing & installation carbon footprint? I'm betting it's a while.

The answer for traditional solar panels is about 2 months IIRC. The answer for these should be significantly less, because you should only count the delta between solar tiles and non-solar tiles rather than the entire footprint.

> The answer for traditional solar panels is about 2 months IIRC.

Do you have a citation for that? A quick Google said normal panels take three years.

Re: Solar panels disguised as terracotta tiles in Pompeii

#18

Post by didgetmaster »

UncleOxidant wrote: post #5

They look cool and all, but how much does this cut down on efficiency?

Since the article fails to compare their efficiency with traditional power cells, I am betting that it is a small fraction of the alternative. If these things were something like 80% as efficient or higher, I'll bet that would have been in the first or second paragraph.

Re: Solar panels disguised as terracotta tiles in Pompeii

#19

Post by bryanlarsen »

teruakohatu wrote: post #16
bryanlarsen wrote: post #11

Earlier quoted context omitted.

The answer for traditional solar panels is about 2 months IIRC. The answer for these should be significantly less, because you should only count the delta between solar tiles and non-solar tiles rather than the entire footprint.

> The answer for traditional solar panels is about 2 months IIRC. Do you have a citation for that? A quick Google said normal panels take three years.

No, I couldn't find it again, it was just from memory. But a check on your number shows that it came from 2004. The price of solar panels has dropped ~90% since 2004, and price is fairly well correlated with carbon footprint.

Re: Solar panels disguised as terracotta tiles in Pompeii

#20

Post by gorkish »

serf wrote: post #13
TeMPOraL wrote: post #9

Earlier quoted context omitted.

If EROI on those panels is negative then it's better to forgo them.

I agree -- but the picture is often more complicated for places that rely heavily on tourism and marketing. The image portrayed by a tourist destination that is making large efforts towards 'green initatives' may be a more enticing sell to the increasing number of 'eco-tourists', many of which have never thought a day in their life about EROI.

I appreciate that you are calling it straight, but it's worth pointing out that there are others who see eco theater as incredibly harmful, particularly when such things start to cannibalize public resources and funding. Take, for example, all current and past solar roadway projects.

I also want to be clear that I am not passing any judgement on these tiles. I don't know the economics or the funding of this project in any way. But it does seem to have plenty of indicators for being a boondoggle.

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