EEVblog #632 - Solar Roadways Are BULLSHIT!

[Towger]

the first commercial ADSL modem probably ran pretty well, I bet there were a number of prototypes that led up to the released product

Freeelectrion talking about his work designing the first ADSL modem:
https://theamphour.com/169-an-interview-with-vincent-himpe-escaped-electron-elocution/

The thing is, it appears there were no real prototypes.  The first install used the first panels, which they then replaced and there was nothing about the fire in the control box in the report.  I would expect initial prototypes to be tested in house, before being given to the customer.

[PlainName]

Sorry, I can't listen to the amphour so have no idea how that relates to this (although I'm sure it is very interesting in its own right). Except that pointing to it probably misses the point being raised. Instead of ADSL modems try quadcopters or radio or, well, have all of your projects worked perfectly second try?

Didn't they have a forecourt paved in these things originally, before this trial? Presumably those would be the mk1 if this lot are the mk3.

[Fungus]

Rather than be pedantic about the detail, think about what he's trying to get across: the state of the art changes and things that one wouldn't previously dream of become the norm.

Some statements are made in error, eg. "9600 baud is the maximum transmission speed physically possible over a phone line" was based on the false assumption that telephone exchanges wouldn't change.

Other statements are based on hard limits like the amount of sunlight falling per square meter. No amount of improvement in solar panels can boost the sun's output.

[madires]

The maximum possible efficiency for silicon solar cells of 29% is a hard limit, but by stacking cells designed for different parts of the light spectrum the total efficiency can be significantly higher. Anyhow, it won't change the game. Standard PV modules will be still more economic than Solar Roadways. If there are huge improvements of the efficiency by stacking cells Solar Roadways' efficiency won't increase by the same rate because of the thick glass.

BTW, the bandwidth limit of about 3kHz for a telephone call is something completely different than the bandwidth of a telephone wire. Also please note that baud is the unit of the symbol rate. It's not the data rate.

[nctnico]

You should ask for your money back. Phone lines have never had a limitation of 9600 baud. On the other hand ADSL only runs at 4000 baud.

Shannon & Hartley don't agree with you:
https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem

Let's not start a potato potaato discussion. The fact is that (A)DSL grossly exceeds what has been deemed the absolute limit for a very long time.

[coppice]

You should ask for your money back. Phone lines have never had a limitation of 9600 baud. On the other hand ADSL only runs at 4000 baud.

Shannon & Hartley don't agree with you:
https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem

Exactly how do they disagree with me?

Let's not start a potato potaato discussion. The fact is that (A)DSL grossly exceeds what has been deemed the absolute limit for a very long time.

Comms books in the 1960s documented the kind of OFDM used in ADSL, although they hadn't coined the term OFDM for it back then. In those days it was described as a way to conceptually get close to Shannon, but one which would probably never be economically feasible. It turned out the semiconductor progress was much greater than most people expected.

[Maxlor]

I stumbled across this picture today (see attachment 1)

It's part of a regional concept with the goal of making the entire region self-sufficient, energy-wise. While they haven't actually built this part yet, I'm kinda happy to see that if they're going to do it, they're doing it right.

Oh and btw, we've had solar roadways here for decades. They're not as spectacular as some of the newer proposals, but the upside is, they actually work! (see attachment 2)

[digsys]

These are 2 good ideas, much much better than the stoopid in-road sheet, but they have 1 weakness. In an accident, and we get them daily here,
it's a HUGE repair bill ! Plus the danger of electrocution (depending on voltage) ... which you could run at 48V, but losses are higher.
I submitted a plan ages ago, where the panels were mounted on our noise walls, but starting at least 2 car heights up.

[PlainName]

How does a translucent solar panel work?

[coppice]

How does a translucent solar panel work?

They are not just translucent,. The panels over the two carriageways are facing in opposite directions, so one of them is definitely tilting the wrong way.

[coppice]

I've seen a lot of solar panels along the verges of highways in Bavaria. As long as they are tilting in roughly the right direction, it seem a good way to achieve reasonable use of otherwise fallow land. The ones in the picture above seem rather close to the highway, so at busy times it looks like there could be heavy shading. The ones I have seen in Bavaria are on wider verges, and have more clearance to minimise shading.

Cars and trucks leave a lot of greasy grim along the verges of highways. I wonder how much effort is needed to keep these verge based panels clean.

[PlainName]

one of them is definitely tilting the wrong way

That struck me, but being charitable I figured the road might be north/south so each side might be appropriately tilted for half the day.

[Maxlor]

In an accident, and we get them daily here, it's a HUGE repair bill !

Crashes aren't that common here. I'd guess the panels would get hit less than once per year. While mounting the panels higher up might keep them saver in the event that someone does run into the side of the road, it also makes cleaning and servicing much more cumbersome. I'm guessing that's why they decided to keep them near ground level (they seem to be about 1.5m up, and behind the guard rail)

one of them is definitely tilting the wrong way

That struck me, but being charitable I figured the road might be north/south so each side might be appropriately tilted for half the day.

It is a north/south road indeed. But keep in mind this is CGI, it hasn't actually been built yet (unlike the installation in the second image.) If they actually do it, it'll probably not end up looking exactly like that.

[PlainName]

it'll probably not end up looking exactly like that

Indeed, hence my original question. The difference between what's shown and the probability that it will be like miles and miles of tunnels is quite significant.

Hmmm. Maybe they'll use the solar panels output to power lighting under the canopies...

[mikerj]

How does a translucent solar panel work?

They are not just translucent,. The panels over the two carriageways are facing in opposite directions, so one of them is definitely tilting the wrong way.

If both panels were tilted the same way they would need some pretty heavy duty drainage in the middle.

[msg90]

Hi,
is the Jeff Jones Square Sandpoint, Idaho Solar Roadways project hooked up to something like PV Output website, where it would collect the stats on how much electricity did the thing produce and/or consume? I have a vague memory of it being shown in one of the videos, but I can't find it. Thanks.

[ataradov]

Main site https://www.sandpointidaho.gov/visiting-sandpoint/solar-roadways#ad-image-5
There is a link to energy production page, but it throws some error now.

[coppice]

Oh and btw, we've had solar roadways here for decades. They're not as spectacular as some of the newer proposals, but the upside is, they actually work! (see attachment 2)

I've seen a lot of that roadside type of solar panel in Germany. The idea seems basically sound, making use of otherwise wasted land. However, some of them seem to get a lot of shading from vehicles on busy Autobahns, and I wonder how often they need cleaning of tarry deposits that close to the vehicles. A grass roadside can look pretty polluted, and that's a living system with some self cleaning properties.

[PA0PBZ]

Holland: Google street view

[djos]

Holland: Google street view

The first practical Solar Road Way! 

Although they may wish to prune some of the trees to prevent shading from their overhangs.

[boffin]

Some statements are made in error, eg. "9600 baud is the maximum transmission speed physically possible over a phone line" was based on the false assumption that telephone exchanges wouldn't change.

56kbit modems run at (max) 3429 baud (symbol changes/sec)

Also, the bandwidth available in a 'telephone call' is limited by the muxing of multiple phone lines onto a single trunk for exchange to exchange communication, approx 3khz worth of bandwidth.  ADSL uses the full copper from the CO to your residence, not limited by CO to CO trunking.

[Psi]

Solar roadways are dead.

The next big 'in' thing is solar railroad tracks! 
100's of miles of rail tracks all covered in silicon cells.
And the best part, there's two rails, so you can power the train!

[Nominal Animal]

The next big 'in' thing is solar railroad tracks!

Yes!  They can save tons of steel by using silica for the rails too.