1924: "Solar Panels"

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DieInRealLife
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1924: "Solar Panels"

Postby DieInRealLife » Mon Dec 04, 2017 4:32 pm UTC

Image

Title Text: This works for a surprising range of sunlit things, including rooftops (sure), highway surfaces (probably not), sailboats (maybe), and jets, cars, and wild deer (haha good luck).

I don't really see the purpose of the "When running, is it hot to the touch?" query. Do solar panels have some inherent problem when heated?

groszdani
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Re: 1924: "Solar Panels"

Postby groszdani » Mon Dec 04, 2017 4:42 pm UTC

A somewhat relevant question that's missing is "Is it exposed to sun?".

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Re: 1924: "Solar Panels"

Postby @maniexx » Mon Dec 04, 2017 4:44 pm UTC

This tells me I should put solar panels on my solar panels. Huh.
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Re: 1924: "Solar Panels"

Postby CelticNot » Mon Dec 04, 2017 4:56 pm UTC

DieInRealLife wrote:I don't really see the purpose of the "When running, is it hot to the touch?" query. Do solar panels have some inherent problem when heated?


A quick Googling gives me this: How Solar Panel Temperature Affects Efficiency

Which, if accurate (standard disclaimers apply), suggests that deserts aren't nearly as useful a location for solar energy stations as I assumed.
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Re: 1924: "Solar Panels"

Postby Mutex » Mon Dec 04, 2017 4:59 pm UTC

CelticNot wrote:
DieInRealLife wrote:I don't really see the purpose of the "When running, is it hot to the touch?" query. Do solar panels have some inherent problem when heated?


A quick Googling gives me this: How Solar Panel Temperature Affects Efficiency

Which, if accurate (standard disclaimers apply), suggests that deserts aren't nearly as useful a location for solar energy stations as I assumed.

The increase in energy from more sunlight is greater than the losses due to temperature. Source: Someone on this forum last time this came up.

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Re: 1924: "Solar Panels"

Postby Hiferator » Mon Dec 04, 2017 5:04 pm UTC

I think there is an implied filter that restricts input to places in which solar panels could operate and not obstruct anything else.

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Re: 1924: "Solar Panels"

Postby Reka » Mon Dec 04, 2017 5:08 pm UTC

I don't see how the flowchart gives a result of "probably not" for highway surfaces, as the title text claims.

Does it move around? No. Is there an empty space nearby where it would be easier to put them? Depends on the highway, but sometimes the answer is definitely No. Thus, the flowchart says "Sure", not "Probably not".

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Re: 1924: "Solar Panels"

Postby Jorpho » Mon Dec 04, 2017 5:19 pm UTC

jets, cars, and wild deer (haha good luck).
A Gentlemen Broncos reference?
https://www.youtube.com/watch?v=qdpFpfIBkXc

(That is apparently a rather terrible film.)

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Re: 1924: "Solar Panels"

Postby HES » Mon Dec 04, 2017 5:25 pm UTC

I'm glad the whole solar roads thing died away. This is the crux of that issue:
xkcd wrote:Is there an empty space nearby where it would be easier to put them
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Re: 1924: "Solar Panels"

Postby sonar1313 » Mon Dec 04, 2017 5:45 pm UTC

HES wrote:I'm glad the whole solar roads thing died away. This is the crux of that issue:
xkcd wrote:Is there an empty space nearby where it would be easier to put them

That was a completely insane idea. I remember getting in an argument with someone (not here) about those. They were insistent that parking lots would be first, as a sort of proof of concept, then roads themselves. Parking lots would all be solar panels in the not too distant future. I had to ask: why not put the solar panels on a roof over the parking lot, which would prevent 1) the need for overengineering the ridiculous hell out of the solar panels, 2) cars shading the damn things all day, and 3) every single force that damages pavement from damaging the solar panels.

(Plus they'd be closer to the sun! I bet someone could figure out the tiny efficiency boost from that.)

An idea defeated that easily never really had any business in the marketplace of ideas.

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Re: 1924: "Solar Panels"

Postby DanD » Mon Dec 04, 2017 6:22 pm UTC

DieInRealLife wrote:I don't really see the purpose of the "When running, is it hot to the touch?" query. Do solar panels have some inherent problem when heated?


I assumed that was an energy requirements versus energy provided filter. If something runs cool to the touch, it's energy demand is probably somewhat low, and might be able to be sustained with solar panels. If it runs hot to the touch, that means it's eating through energy quickly, and unless it has a very low duty cycle, the panels won't be able to keep up.

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Re: 1924: "Solar Panels"

Postby Ranbot » Mon Dec 04, 2017 6:23 pm UTC

sonar1313 wrote:
HES wrote:I'm glad the whole solar roads thing died away. This is the crux of that issue:
xkcd wrote:Is there an empty space nearby where it would be easier to put them

That was a completely insane idea. I remember getting in an argument with someone (not here) about those. They were insistent that parking lots would be first, as a sort of proof of concept, then roads themselves. Parking lots would all be solar panels in the not too distant future. I had to ask: why not put the solar panels on a roof over the parking lot, which would prevent 1) the need for overengineering the ridiculous hell out of the solar panels, 2) cars shading the damn things all day, and 3) every single force that damages pavement from damaging the solar panels.

(Plus they'd be closer to the sun! I bet someone could figure out the tiny efficiency boost from that.)

An idea defeated that easily never really had any business in the marketplace of ideas.

Agreed, and I've said all the same things to others. Imagine the hit to ROI when you discover a 50+ year old public water or sanitary pipe sprung a leak under that fancy new solar road.

Another advantage to putting solar panels over a parking lot, related to shade you stated, they protect people and their cars from rain and snow too. Ever had to walk to your car with a armful of groceries in a downpour or blizzard? Not fun. In some areas overhead panels could reduce the cost of snow plowing/removal by directing the snow to the parking lot sides or medians. Even regular roads could benefit from a solar panel canopy over them to reduce rain, snow, sun glare, etc. for driver safety in addition to the solar power benefits.

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Re: 1924: "Solar Panels"

Postby Soupspoon » Mon Dec 04, 2017 7:10 pm UTC

Deserts (and other maybe hot/certainly empty landscapes) are also starting to be equipped with double-sided Pv-panels, to capture the ambient light reflected from the bare ground beneath (that missed all panels as it passed the upward-facing surfaces). More efficient, yet, after snowfalls (which also may or may not self-melt off of the upper panels) in such environments where the hot and sunny elements to the solar farm do not preclude such precipitation, frozen at that.

This actually came up as a discussion topic only the other day, for me, but I can't remember why or where.

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Re: 1924: "Solar Panels"

Postby Mutex » Mon Dec 04, 2017 7:25 pm UTC

sonar1313 wrote:Parking lots would all be solar panels in the not too distant future. I had to ask: why not put the solar panels on a roof over the parking lot, which would prevent 1) the need for overengineering the ridiculous hell out of the solar panels, 2) cars shading the damn things all day, and 3) every single force that damages pavement from damaging the solar panels.

Like this?

Image

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Re: 1924: "Solar Panels"

Postby JetstreamGW » Mon Dec 04, 2017 7:44 pm UTC

HES wrote:I'm glad the whole solar roads thing died away. This is the crux of that issue:
xkcd wrote:Is there an empty space nearby where it would be easier to put them


... Ah... About thaaaat...

They've totally got several municipal contracts right now and are actively working on it.

I know the media isn't really talking about it anymore, but the company doing Solar Roadways hasn't really gone anywhere. Or stopped.

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Re: 1924: "Solar Panels"

Postby somitomi » Mon Dec 04, 2017 8:01 pm UTC

Ranbot wrote:Another advantage to putting solar panels over a parking lot, related to shade you stated, they protect people and their cars from rain and snow too. Ever had to walk to your car with a armful of groceries in a downpour or blizzard? Not fun. In some areas overhead panels could reduce the cost of snow plowing/removal by directing the snow to the parking lot sides or medians. Even regular roads could benefit from a solar panel canopy over them to reduce rain, snow, sun glare, etc. for driver safety in addition to the solar power benefits.

Solar panels over a parking lot are more useful in pretty much any weather: all the energy captured by solar panels on a sunny day is no longer spent on turning your car into a furnace.
I still can't quite comprehend how the "solar road" idea managed to get off the ground in the first place.
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Re: 1924: "Solar Panels"

Postby Ranbot » Mon Dec 04, 2017 9:05 pm UTC

somitomi wrote:I still can't quite comprehend how the "solar road" idea managed to get off the ground in the first place.

By leveraging the power and wallets of stupid people... They crowdfunded $2.2M through an indiegogo campaign in 2014, and then an additional $750K grant from the DOT. That will keep their family business going for a while. I just hope that the DOT grant also provides useful research on building materials other than just solar roads.

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Re: 1924: "Solar Panels"

Postby Old Bruce » Mon Dec 04, 2017 11:36 pm UTC

somitomi wrote:I still can't quite comprehend how the " solar road" idea managed to get off the ground in the first place.

So many puns, too tired to make them, I leave them as an exercise for the readers. [winky-face emoticon]

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Re: 1924: "Solar Panels"

Postby KarenRei » Tue Dec 05, 2017 1:53 am UTC

Big screwup in this comic by using the word "easier" rather than "better". It may be "easier" for someone to put solar panels in their yard than on their roof. Heck, it might even be easier for them to put them in a tree. That doesn't make it "better".

Also, re: solar roadways: Actually, the concept is far from dead. More notably, there's already one such trial roadway in France:

Image

Not the same people and not the same (stupid) technology; this is from a company called Colas. No embedded, mathematically-impossible snow melting electronics or anything like that - just simple solar panels. No textured glass surface - just a spray on transparent textured resin that makes it rough:

Image

They're also not doing it as "from scratch" roads; it's a product that can be paved over existing roads (if you were building a new road, it could be used in lieu of the top traction layer). It's been lab tested supposedly to withstand regular wear from even semi trucks and snowplows, with a 10-20 year lifespan (after which it can be stripped off and replaced). That's not implausible; there's constantly new research on new (non-solar) road surfaces, and asphalt paving isn't exactly the most durable of substances (water gets in and frost-heave damages the road). I'm not sure what polymer is used as the resin binder, but the aggregate is glass beads, which are certainly a valid choice of aggregate (good compressive strength, and you can get glass beads for sandblasting at around $100-200/tonne)

That said, it's not at present a practical product. The durability in real-world conditions won't be known for a while (it just went in last year), but assuming it holds up, the price is still very much at "in-development" levels (about 6x more per watt than traditional solar). But Colas is confident that they can bring it down to competitive pricing. IMHO, part of the problem appears to be how they have to lay it:

Image

If they could have a rollable product that could unreel straight from a truck, that should reduce labour costs dramatically.

Certainly, solar roadways are a more technologically challenging task in most regards (except for wind resistance, and that they don't need support frames). In cold climates, a significant loss of generation can be expected from winter snow and ice. Generation is reduced due to the angling, etc. The resin will absorb part of the light. One could bring up shading from vehicles, but that's largely a myth (pull up a random interstate on Google Maps, you'll see that only a couple percent is shaded at any given point in time) - still, you lose a couple percent from that. Etc. They'll also need to make sure that whatever wear does occur does not lead to hazardous or otherwise environmentally problematic dusts. But the advantages - again, with the giant caveats that durability and cost competitiveness can be proven - should not be ignored either:

* Reduced land footprint (using the same land for multiple purposes). Some people are indifferent to total land usage, but others are very much not.

* No further obstruction of view (aka, if you built in a field off to the side, or over a roadway, you're changing people's view, generally in a way that people would consider "for the worse"). Should come with literally zero NIMBY effect.

* "Doing double duty". If built on a new road, it lets you avoid the need to lay an asphalt or concrete traction layer (saving money - it's a real cost in road construction). If built atop an existing road, it protects the underlying layer; the 10-20 year replacement of the solar layer come in lieu of repaving of the underlying traction layer, which also has to happen at regular intervals (and is - again - a real cost).

* In theory, the lowest possible labour cost in construction for any solar project. It's just a long straight line; so long as you have a continuous deployment mechanism, it's just "drive down the road" (no need to lay any foundations, build frames, attach things individually to said frames, etc - or contrarily, to install panels to building rooftops one at a time, including engineering analyses for the added weight, with each building needing its own inverter).

Is there lower hanging fruit? Of course - much lower. Still, I don't object to companies working on this, to see how low the production / deployment costs can get and how well they stand up to traffic. For a long time, the cost of solar power in general was absurdly high. Should it have been ignored? So was wind power. Should it have been ignored? So was pretty much every technology that we rely on today. There are real potential benefits (even if some people disagree on the degree), and the concept hardly runs afoul of physics. So I'm totally okay with giving them a shot to see where the tech goes. At least Colas doesn't appear to be run by a couple loons who never took a physics course.

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Re: 1924: "Solar Panels"

Postby rmsgrey » Tue Dec 05, 2017 2:25 am UTC

I've been seeing a lot of ads recently for a "smart road" that lights up red green or white in suitable patterns to indicate hazards and create impromptu crossing points.

https://www.youtube.com/watch?v=tOy0wT1X_9g

I've also seen a version where it shows a cyclist and a pedestrian concealed from each other by a van waiting at the crossing, and the cycle lane changing to warn the cyclist, pre-empting the collision that might otherwise have happened (other interactions seem less immediately useful)

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Re: 1924: "Solar Panels"

Postby Eebster the Great » Tue Dec 05, 2017 2:41 am UTC

Karen, while your post is interesting and certainly a far cry from the "solar freaking roadways" lunacy, I have to say I am still thoroughly unconvinced by the concept. The major advantages relating to land use and ease of construction only really apply to areas where the land near the highway is built up, and those areas tend to get significant traffic. If you are out in the middle of nowhere, there is nothing stopping you from just building a solar farm using existing technology. And I think the losses you sustain are much more significant than you are imagining. The surface is already both more expensive and less efficient than ordinary solar panels even before you consider higher repair costs and cosine losses. I also have a hard time believing it would remain clean for long, and cleaning roads is very expensive, too. It isn't clear that these are issues that will ever be resolved, or even can be.

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Re: 1924: "Solar Panels"

Postby Solra Bizna » Tue Dec 05, 2017 7:14 am UTC

Ranbot wrote:Imagine the hit to ROI when you discover a 50+ year old public water or sanitary pipe sprung a leak under that fancy new solar road.


One of the selling points was (is?) that in such a situation, you cheaply remove the tile(s) that are in the way of repairing the pipe, repair the pipe, then cheaply replace the tiles. Way easier than going at concrete/asphalt with a jackhammer and then putting it back together afterward.

...of course, there are lots of other serious problems with Solra Solar Roadways.

When they were first crowdfunding the project, I was neutral to mildly hopeful about them. The biggest problems seemed to me to be engineering problems, not fundamentally insoluble. The maintenance savings in particular had me excited; instead of effectively paving another road every few years, all you'd have to do is replace individual damaged tiles. Then somebody pointed out the "conservation of energy" issues like visible-in-sunlight solar-powered LEDs, and covered-in-snow-that-the-sun-isn't-melting solar-powered snow melters, and I started to approach the concept with a much more critical eye...

Eebster the Great wrote:The major advantages relating to land use and ease of construction only really apply to areas where the land near the highway is built up, and those areas tend to get significant traffic. If you are out in the middle of nowhere, there is nothing stopping you from just building a solar farm using existing technology. And I think the losses you sustain are much more significant than you are imagining.


Actually, with "dumb" solar panel surfaces like Karen's post talks about, that's not the right part of the equation to look at. The question isn't "is putting a solar panel on this road better than putting a solar panel beside it?", it's "is making this road with a solar panel better than making it without one?". The answer to both questions is no with current technology, but if dumb panels get really cheap, and if that resin is a competitive alternative to asphalt as a road surface—
Eebster the Great wrote:I also have a hard time believing it would remain clean for long, and cleaning roads is very expensive, too.

—and that ends up not being a problem somehow... (Come to think of it, I don't actually have any good data on road dirtiness.)

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Re: 1924: "Solar Panels"

Postby Mikeski » Tue Dec 05, 2017 7:51 am UTC

Solra Bizna wrote:(Come to think of it, I don't actually have any good data on road dirtiness.)

Would you ever consider eating food after you dropped it on a road?

...there's your data. :mrgreen:

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Re: 1924: "Solar Panels"

Postby Wee Red Bird » Tue Dec 05, 2017 8:48 am UTC

Solra Bizna wrote:One of the selling points was (is?) that in such a situation, you cheaply remove the tile(s) that are in the way of repairing the pipe, repair the pipe, then cheaply replace the tiles. Way easier than going at concrete/asphalt with a jackhammer and then putting it back together afterward.

Just don't fit them in areas where some joker will lift the tiles for fun or to sell for profit. Which would be just about anywhere.
One street had its paving slabs stolen. Couple of guys came along in a white van, wore hi-vis jackets. Told everyone who asked that the pavement was being replaced by a nice new smooth asphalt one. Took a few weeks of not having a pavement before the locals started complaining, by which time they were long gone.

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Re: 1924: "Solar Panels"

Postby Wee Red Bird » Tue Dec 05, 2017 8:51 am UTC

Areas you probably shouldn't put solar panels - Scotland.
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Re: 1924: "Solar Panels"

Postby HES » Tue Dec 05, 2017 10:40 am UTC

rmsgrey wrote:I've been seeing a lot of ads recently for a "smart road" that lights up red green or white in suitable patterns to indicate hazards and create impromptu crossing points.

The one I've seen is an advertising gimmick by an insurance company. I am reassured that the comments below are laypeople pointing out how dumb instant crossings are. Roads have to be predictable to be safe.

Solra Bizna wrote:Way easier than going at concrete/asphalt with a jackhammer and then putting it back together afterward.

Cranes are expensive. Lifting operations are hazardous. Working area is increased... it's never as clear cut as you think.

As for the more sensible trial in France, I still don't see it being utilised beyond low-traffic applications as a "green credentials" gimmick. Great for new office developments trying to get planning permission, not so much for a highway authority.
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Re: 1924: "Solar Panels"

Postby peregrine_crow » Tue Dec 05, 2017 1:54 pm UTC

Solra Bizna wrote:
Ranbot wrote:Imagine the hit to ROI when you discover a 50+ year old public water or sanitary pipe sprung a leak under that fancy new solar road.

One of the selling points was (is?) that in such a situation, you cheaply remove the tile(s) that are in the way of repairing the pipe, repair the pipe, then cheaply replace the tiles. Way easier than going at concrete/asphalt with a jackhammer and then putting it back together afterward.

Is there any particular reason why this solution should be exclusive to solar roads? We don't usually make highways out of bricks any more, presumably because it is really hard to get to get the surface to be even enough for cars to comfortably drive at highway speeds. So what is different about these solar tiles that you can lay them much more flat than regular concrete tiles?
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Re: 1924: "Solar Panels"

Postby Ranbot » Tue Dec 05, 2017 3:01 pm UTC

peregrine_crow wrote:
Solra Bizna wrote:
Ranbot wrote:Imagine the hit to ROI when you discover a 50+ year old public water or sanitary pipe sprung a leak under that fancy new solar road.

One of the selling points was (is?) that in such a situation, you cheaply remove the tile(s) that are in the way of repairing the pipe, repair the pipe, then cheaply replace the tiles. Way easier than going at concrete/asphalt with a jackhammer and then putting it back together afterward.

Is there any particular reason why this solution should be exclusive to solar roads? We don't usually make highways out of bricks any more, presumably because it is really hard to get to get the surface to be even enough for cars to comfortably drive at highway speeds. So what is different about these solar tiles that you can lay them much more flat than regular concrete tiles?

The short answer is roadway tiles are unnecessary because asphalt is really cheap, relatively, both in material costs and not very labor intensive to remove/replace/repair with common construction equipment. When building roads/parking lots a lot more effort goes into making the underlying base materials suitable for asphalt (material type, compaction, testing, grades, etc.) than the actual asphalt, and using roadway "tiles" (concrete, solar, or otherwise) is not going to remove the need to carefully prep the underlying base materials in much the same way. Although, I don't have numbers to compare, I suspect the cost difference would be mainly in using a more expensive surface material (tiles vs asphalt) and long-term durability, but you have to actually prove the durability savings is better than the cheaper asphalt. Side note, removed asphalt is very recyclable, and typically sent back to the asphalt plant to make new asphalt.

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Re: 1924: "Solar Panels"

Postby KarenRei » Tue Dec 05, 2017 3:07 pm UTC

Is there any particular reason why this solution should be exclusive to solar roads?


No. Concrete and brick pavers are used for roads in some places, but generally for aesthetics; historically, they've usually been more expensive because they're generally laid by hand. That said, you can now get paver-laying machines, so that may change the economic case.

Image

One of the arguments for pavers is that they let water seep down to the soil underneath them, reducing runoff. Some pavers are even specifically designed to maximize the amount of water that flows through them. A downside is that they often have worse ride quality because of the joints between pavers.

and covered-in-snow-that-the-sun-isn't-melting solar-powered snow melters, and I started to approach the concept with a much more critical eye...


Yep. That was head-smackingly bad. I can't believe they didn't bother to run the numbers on the snow.

It did however get me thinking about alternatives. Some things that don't run afoul of conservation of energy:

1) Melting frosts or thin layers of black ice. You're not going to melt snow or thick ice off, but you could melt thin layers off when present to improve traction

2) Melting the bottom layer of snow or ice so that everything above is no longer attached to the road. Roads generally don't slope enough for one to expect snow or ice to just slide off, but it might make it more easily kicked off by passing cars. Might.

3) Trying to prevent snow from landing in the first place. If you had air channels (for solar cell cooling) and periodic pinholes, you could potentially create a mild "airhockey table" effect that would encourage snow to drift to the sides, without being dramatic enough to have a meaningful amount of lift on car tires. Snow is readily lofted by air currents (just blow a little on falling snowflakes, or watch how they avoid your windshield when you're moving). That said, I've done neither the math nor prototyping to determine whether this could be done with a small enough amount of electricity to be practical.

That said, I like how Colas is pursing the KISS principle here. If they can manage to prove durability and economics on a simpler system, it may make more complex systems more appealing. The big issue with complex systems is that mass production is absolutely critical to keeping costs down. And mass production means large amounts of investment capital, which in turn means large institutional investors believing in your product. It'll be a lot easier to believe in elaborate electronics-tile-based solar roadways if there's at least some type of solar roadway that works.

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Re: 1924: "Solar Panels"

Postby peewee_RotA » Tue Dec 05, 2017 3:31 pm UTC

This particular comic is a bit off. The first is that the concept is ambiguous. "Should I Put Solar Panels On It". That is supposed to literally mean on the surface of the object. Not whether or not the system as a whole should have solar panels somewhere. The second part is the chart assumes that you are already using solar panels as part of the system. You are supposed to enter into the flow chart having a system that should have solar panels and you're deciding where to place them.

That's a really obscure place to start from without better direction.

Here are way better examples where there was any amount of reasonable assumptions about the reader:
https://xkcd.com/518/
https://xkcd.com/627/
https://xkcd.com/1688/

Imagine any of these without the explanations. This is probably the laziest entry he's ever made. And I'm including frames from Time where nothing changed.
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Re: 1924: "Solar Panels"

Postby Ranbot » Tue Dec 05, 2017 3:43 pm UTC

KarenRei wrote:One of the arguments for pavers is that they let water seep down to the soil underneath them, reducing runoff. Some pavers are even specifically designed to maximize the amount of water that flows through them. A downside is that they often have worse ride quality because of the joints between pavers.

In areas prone to frost heaving, water infiltration under the road surface can destroy the road within a few seasons by ice expansion/heaves, but it's a good feature in warm urban areas to reduce flow into public storm sewers.

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Re: 1924: "Solar Panels"

Postby Soupspoon » Tue Dec 05, 2017 4:10 pm UTC

Wee Red Bird wrote:Areas you probably shouldn't put solar panels - Scotland.
Today sunrise is at 8:31 and sunset at 15:28.


The answer is obvious. Power things around the road from Solar Roadways on the exact other side of the planet, and vice-versa, to take advantage of the correspondingly longer and complimentarily-tiled daytime on the other side of the planet. In Scotland's case, a deal would probably have to be done with Cherbourg (draw upon the Auld Alliance!) for rights to tap the solar resources of the Antipodes Island group in the extreme South Pacific.

Solra Bizna wrote:Then somebody pointed out the "conservation of energy" issues like visible-in-sunlight solar-powered LEDs, and covered-in-snow-that-the-sun-isn't-melting solar-powered snow melters, and I started to approach the concept with a much more critical eye...

As you're laying the wires for the above, across at least half of a Great Circle of your choice, make it pass through other territories you can make deals with to top-up your energy needs, experiencing various other phases-shifted day/night cycles. Two mostly opposing trails to the same opposite-side location could cover times when intermediate feeds on one line are in darkness themselves, and then the other line is sunlit In fact, keep adding great-(semi-)circles round the planet in as many directions as you need! Where your GSCs cross other locations' GSCs (there's more equatorial land than there is any other equivalent latitude, so that should even things out, demand-wise) there'd have to be an arbitration process to decide who gets that location's unused solar energy, but that's surely just politics, and that never goes wrong!

(Now, on an unrelated issue, I must take my leave as I go and buy shares in copper and other cable materials.)

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Re: 1924: "Solar Panels"

Postby HES » Tue Dec 05, 2017 4:59 pm UTC

Ranbot wrote:
KarenRei wrote:One of the arguments for pavers is that they let water seep down to the soil underneath them, reducing runoff. Some pavers are even specifically designed to maximize the amount of water that flows through them. A downside is that they often have worse ride quality because of the joints between pavers.

In areas prone to frost heaving, water infiltration under the road surface can destroy the road within a few seasons by ice expansion/heaves, but it's a good feature in warm urban areas to reduce flow into public storm sewers.

Such systems usually have their own drainage systems beneath the road surface, so you're still capturing as much water. There are ways to deal with it locally, but they're largely independent of how you capture the runoff in the first place. You can also do the same thing with porous asphalt instead of pavers.
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Re: 1924: "Solar Panels"

Postby Neil_Boekend » Tue Dec 05, 2017 5:32 pm UTC

We use a lot of "ZOAB" (expanded and translated it means "very open asfalt"). It's awesome in rain but sucks when it's freezing. The salt that melts the snow runs off with the first bit of precipitation and then the next snow doesn't melt anymore.
Mikeski wrote:A "What If" update is never late. Nor is it early. It is posted precisely when it should be.

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flicky1991 wrote:I'm being quoted too much!

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Re: 1924: "Solar Panels"

Postby KarenRei » Wed Dec 06, 2017 1:03 am UTC

Eebster the Great wrote:Karen, while your post is interesting and certainly a far cry from the "solar freaking roadways" lunacy, I have to say I am still thoroughly unconvinced by the concept. The major advantages relating to land use and ease of construction only really apply to areas where the land near the highway is built up, and those areas tend to get significant traffic. If you are out in the middle of nowhere, there is nothing stopping you from just building a solar farm using existing technology. And I think the losses you sustain are much more significant than you are imagining. The surface is already both more expensive and less efficient than ordinary solar panels even before you consider higher repair costs and cosine losses. I also have a hard time believing it would remain clean for long, and cleaning roads is very expensive, too. It isn't clear that these are issues that will ever be resolved, or even can be.


Land use applies everywhere. To reiterate: while you may be indifferent about rededicating huge amounts of virgin or in-use land to power production, many people aren't. And in many places, particularly near where you want to consume it, you'll face NIMBY opposition for doing so.

To sum up your claims:
* The losses are significant: True!
* The surface is more expensive than ordinary solar panels: True!
* Cosine losses: True!
* Would not remain clean long: True!
* Cleaning roads is very expensive: You wouldn't - at least not frequently. You'd just eat the loss of "ordinary" dust and dirt.

There's no question that the energy generation would be lower. I'd expect perhaps 60% of what you'd get for the same area of mounted panels, possibly even less. That is, of course, irrelevant from an area perspective (since it's dual-use surface area), but relevant for panel purchase costs. However, panel purchase costs are only part of the cost of a solar farm (it's not like the old days when solar panels were very expensive and made up most of your capital costs). There's framing, ground anchors, land acquisition / permitting costs, and most importantly, a lot of labour to pay for the installation. For a solar road, there's no framing, the road itself is your anchor, the road's land is already acquired and permitted, and with a proper continuous-reel paving process, labour could be drastically reduced.

It's worth reiterating the other aspect: the surface is dual use. You have to pay for a surface on your road either way. You have to pay to maintain a surface on your road either way. Yes, you're using a more expensive road surface, but from the cost of that road surface, you need to subtract the cost of the road surface you'd otherwise have had to build and maintain. Which is not insignificant.

It's easy to get all focused on material costs. But a huge chunk of both road and solar farm construction is not materials - it's planning, acquisition, permitting, and especially labour. And with a solar road, you get a two-for-one on them.

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Re: 1924: "Solar Panels"

Postby Eebster the Great » Wed Dec 06, 2017 1:36 am UTC

KarenRei wrote:There's no question that the energy generation would be lower. I'd expect perhaps 60% of what you'd get for the same area of mounted panels, possibly even less. That is, of course, irrelevant from an area perspective (since it's dual-use surface area), but relevant for panel purchase costs. However, panel purchase costs are only part of the cost of a solar farm (it's not like the old days when solar panels were very expensive and made up most of your capital costs). There's framing, ground anchors, land acquisition / permitting costs, and most importantly, a lot of labour to pay for the installation. For a solar road, there's no framing, the road itself is your anchor, the road's land is already acquired and permitted, and with a proper continuous-reel paving process, labour could be drastically reduced.

60% is completely unrealistic. I was thinking something more like 30%, optimistically speaking. The dirt is a huge problem. Even on tilting panels raised above ground level, dust accumulation results in losses between 1% and 50%. Cosine losses can already amount to about 20% losses compared to fixed tilt at temperate latitudes, or more than 30% compared to tracking tilt. And this ignores the fact that the panels are already substantially more expensive and less efficient than existing technology.

It's worth reiterating the other aspect: the surface is dual use. You have to pay for a surface on your road either way. You have to pay to maintain a surface on your road either way. Yes, you're using a more expensive road surface, but from the cost of that road surface, you need to subtract the cost of the road surface you'd otherwise have had to build and maintain. Which is not insignificant.

But the new surface is much more expensive, not just to build, but to repair. You have to lay tiles by hand. By comparison, a traditional road surface might as well be free. (Remember, we aren't replacing the entire road, just the surface.) The repair costs are also likely to be very high. Even if the materials are as durable as they say, they won't last as long as asphalt, and repairing them will require replacing the tiles. Let's just say that based on my experience of street repairs, this will not end well.

It's easy to get all focused on material costs. But a huge chunk of both road and solar farm construction is not materials - it's planning, acquisition, permitting, and especially labour. And with a solar road, you get a two-for-one on them.

Do you have any numbers on that? For solar roads, you still have to plan the roads, get permits, and pay for the labor, just like building a farm. It is not at all clear to me that these costs will be lower for the road. As for land acquisition that you keep talking about: yes, that costs money, but I think you are overstating it. Nobody is putting power plants on prime real estate.

Of course all of this ignores other problems that are likely to come up. What if the road doesn't provide good traction in wet or cold conditions? What if it wears more quickly? What if broken tiles pop tires (in a way broken asphalt typically does not)? What if it has a lower coefficient of friction? What if it expands when heated? What if it reflects light into drivers' eyes? Any one of those problems would be more serious than the entire project.

The problem with building on top of roads is that transportation is extremely expensive, extremely important, and extremely dangerous. The idea that roads will have a dual purpose in this way seems intrinsically unlikely to me, since roads have so many other considerations that are simply more important.


Oh, and then there is the issue of actually transmitting the power. How does this project safely transmit so much power from the road to the grid without additional losses and infrastructure?
Last edited by Eebster the Great on Wed Dec 06, 2017 1:45 am UTC, edited 2 times in total.

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Re: 1924: "Solar Panels"

Postby scharb » Wed Dec 06, 2017 1:36 am UTC

Comic works for many things... but not for calculators

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Re: 1924: "Solar Panels"

Postby KarenRei » Wed Dec 06, 2017 1:48 am UTC

To put a more precise point on it: here's the breakdown of the costs for a solar farm:

https://www.nrel.gov/docs/fy16osti/67142.pdf

Page 38: Panels are $0,64/W out of $1,42 on a large (>100MW) solar farm, or out of $1,82 on a small (<5MW) solar farm. That's 45% and 35%, respectively. The non-panel overhead costs are $0,78 and $1,18, respectively. Also remember: solar panels have been on a falling trend for years, and - while they'll fluctuate - the long-term trend looks rosy for even further significant declines (e.g. silicor-process silicon, perovskite cells, etc). So the "soft cost" share of the total will rise with time and the panel cost share will fall.

In the case of the solar road, for a "mature" product, between the increased cost of making panels more durable, combined with their reduced generation, we're probably roughly doubling the module costs per watt (say, $1,30/W). Inverter costs don't change with a solar road. If labour is significantly reduced with direct reel-to-road deployment and the lack of need for foundations and frames (as well as their hardware costs), then balance of plant and EPC are dramatically reduced. Engineering is unified with road engineering. Land is already acquired. Etc, etc, etc. Half of the remainder might potentially be removed. That is, reducing them to $0,39 and $0,59, respectively.

On top of this, you subtract the cost of the traction layer on the road. Here's a breakdown of road costs:

https://capitolfax.com/summary.pdf

Milling and resurfacing a rural road costs around $250k per lane mile. But according to this:

https://www.dot.state.oh.us/Divisions/F ... ermile.pdf

They're $120k. And this:

http://www.ci.punta-gorda.fl.us/home/sh ... ent?id=754

... around $110k. At around 5000 square meters per lane mile, these numbers are around $50, $24 and $22 per square meter, respectively. The first one includes milling to prepare for repaving; the latter two aren't clear. But we're looking on the order of $20 per square meter that is being replaced by the solar road.

At $0,64/W and 20% efficiency (200W/m²), a normal solar panel would be $128/m². These would be a bit more expensive. How much more expensive? You know, I wouldn't be surprised if it's around the aforementioned $20 per square meter. Maybe less; I don't know how complicated the under-layers are to withstand the impact of traffic, but the surface layer is pretty darned simple. So when we offset the road paving savings from the panel costs, they become $1,07 after savings. Adding in our overhead costs above, $1,46 in the >100MW case and $1,76 on the <5MW case.

Basically the same price. And note that we're not even considering the following:

* That you're providing the power to run things like streetlights on the road without having to pay for a separate interconnect
* That you're providing a power interconnect along the road
* That you could co-lay other services when laying the power conduit (something that's part of a solar farm's costs regardless)
* The benefits (some intangible, some tangible) of reduced land use

On the other hand, we're also not considering the likely elevated maintenance costs (difficult to quantify at this point).

To sum up: does all this mean that solar roads will prove to be economic? Of course not. I'd wager that they won't, at least not in the near future. But it's not as preposterous as many people make it out to be (when you take out the nonsense parts of the original proposal and take a more realistic approach like that of Colas). IF - and that's a big IF - they can prove that wear is controllable, that generation can be kept averaging around 60% or better versus "normal" solar panels with costs ~20% or so more than "normal" panels (or some equivalent scenario), and so forth - then yes, solar roadways work. But all this needs to be proven.

Should they be given a chance to try to prove it? IMHO, absolutely. That's quite useful data, for not that much money. Let's see where it goes.
Last edited by KarenRei on Wed Dec 06, 2017 2:27 am UTC, edited 1 time in total.

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Re: 1924: "Solar Panels"

Postby KarenRei » Wed Dec 06, 2017 2:22 am UTC

60% is completely unrealistic. I was thinking something more like 30%, optimistically speaking. The dirt is a huge problem. Even on tilting panels raised above ground level, dust accumulation results in losses between 1% and 50%.


http://ucsdnews.ucsd.edu/pressrelease/c ... n_diego_fi

7,4% difference between cleaned and uncleaned solar panels in California. Not that much. As for roads? Who knows - *we need data*, which is why projects like this matter. Roads are dust generators, but they also have agitation of surface water when it rains by tires, and cars kicking up collected dust when it doesn't. Some quick googling for dusty roads (in dusty areas, where *everything* is getting coated by dust) shows that tires appear to actually *clean* roads of dust. Eg:

Image

Compare where the tires have been traveling to where they haven't.

So again, to reiterate: we need data. Real-world data, not speculation.

Cosine losses can already amount to about 20% losses compared to fixed tilt at temperate latitudes, or more than 30% compared to tracking tilt


Or 0% difference relative to frameless commercial rooftop solar, which nobody in these discussions ever seems to have any opposition to. For utility scale farms, it's about half fixed tilt and half tracking. So call it 7,4% dust and 25% cosine. That's 70%. I said 60%. Where's the problem? How much loss exactly are you expecting in the resin coating?

And this ignores the fact that the panels are already substantially more expensive and less efficient than existing technology


At present they're substantially more expensive. In the long run, I seriously doubt that. Yes, they need to be able to take varying compressive loads, and they have a wear surface. But they also don't need mounts, foundations, and face no meaningful wind loads (adhesive bound to the substrate). Yeah, I think they'll be more expensive in the end. But I suspect that in the end, the cost over non-road-panels will be about the same as the money saved by not having to build the road traction surface that you'd have otherwise had to build. Who knows? *We need data*.

"Less efficient": it sounds like you're trying to double-count our aforementioned discussion of dust, angles, etc.

But the new surface is much more expensive, not just to build, but to repair. You have to lay tiles by hand.


I'm not sure you've been reading what I've actually been writing. I've been talking about the scenario where - as the technology matures - they transition from hand-laid pieces to continous reel deployment from a specialized solar paving vehicle. Your mention of tiles makes me think you're still thinking of the stupid "Solar Freaking Roadways!" people.

By comparison, a traditional road surface might as well be free.


Nothing is free.

The repair costs are also likely to be very hig. Even if the materials are as durable as they say, they won't last as long as asphalt


Says who? No, seriously. Can you even tell me what the layers of their panels are made out of? What the resin that binds the glass bead aggregate? Etc? If you don't even know the structure of what you're talking about, how do you feel like you can comment *at all* about how fast it will wear? And Asphalt isn't exactly a long-wearing substance. It degrades in the sun and devolatilizes and oxidizes when exposed to air. This makes it progressively more brittle. Maintenance is usually needed after ~15 years or so.

two-for-one ... Do you have any numbers on that?


Yes, see my last post (which I was writing while you write yours)

For solar roads, you still have to plan the roads, get permits, and pay for the labor, just like building a farm


And when you're done, you have both a road *and* a farm, hence the comments about two-for-one. The road is literally the foundation-slash-frame for your panels, and the panels are literally the traction layer of the road.

What if the road doesn't provide good traction in wet or cold conditions?


You mean, if Colas developed a bad traction coating? Then they need to make a better one or give up, obviously. You know how we find out how good the traction is? By testing, rather than just throwing our hands up in the air and saying "anything new will fail."

And IMHO, do you know what you call "small grains bound with a polymer resin onto a surface" in real life? We call it sandpaper. I actually expect traction to be quite good.

What if it wears more quickly?


See above.

What if broken tiles pop tires


Okay, you are very clearly not reading. We are not talking about the "Solar Freaking Roadways!" people and their overcomplicated glass tiles. . We're talking about the potential evolution of something like what Colas is testing in France. Look at it:

Image

What if it has a lower coefficient of friction?


What if we started repeating "what ifs" that we had already raised to try to make it sound like there were more potential things that could go wrong than we could think up?

What if it expands when heated?


What, you mean like asphalt?

What if it reflects light into drivers' eyes?


It doesn't:

Image

Next question.

The problem with building on top of roads is that transportation is extremely expensive, extremely important, and extremely dangerous.


Which is why you do trials like what Colas is doing in France to see how it works in the real world. Do you understand what I'm saying? I'm saying collecting data on a meaningful concept that may or may not work out - but could - is a good thing.

Oh, and then there is the issue of actually transmitting the power. How does this project safely transmit so much power from the road to the grid without additional losses and infrastructure?


Surely you know that power lines are a thing. Whether in underground conduits or overhead wires. Power is transmitted within the roads to branch points (such as rows interlinked in parallel, columns in series, up to the branch DC voltage), and from the branch DC lines to inverters for AC wherever desired. Nothing special about that. For Colas's system, it looks like there's a primary conductor in the midline of the lane. It appears to reach what may be an inverter next to the power line via an underground conduit - although that's speculation.

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Re: 1924: "Solar Panels"

Postby Mikeski » Wed Dec 06, 2017 3:05 am UTC

Someone needs to tell them that their substrate material can't be white, at least. Lane-departure sensors and (potentially) self-driving cars will go nuts with those extra white lines everywhere.

Heck, human drivers might go nuts with them in weather conditions worse than those in the pic. Or at night.


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