EEVblog Electronics Community Forum

EEVblog => EEVblog Specific => Topic started by: BobC on May 13, 2015, 06:15:01 am

Title: EEVblog #743 – Solar Roadways Test Results
Post by: BobC on May 13, 2015, 06:15:01 am
I can think of one very useful application for a solar path: To provide power in scenic locations, such as parks, that may be off the grid, and to do so with minimal visual impact on the surroundings.

While it may be 4x the cost per watt-hour compared to conventional solar installations, I can't think of a less unsightly way to get local power.  I'm thinking of locations like the bottom of the Grand Canyon, or island parks.

A niche, to be sure, but it may be common enough to warrant developing and deploying the technology.

So far as the price goes, it would only need to be cheaper than laying underground cables out to the nearest power station.  (And in many park-like locations, securing permission to run an underground power line could cost more than the solar path.)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: miguelvp on May 13, 2015, 06:24:06 am
It's customary to embed the video on the first post:

https://www.youtube.com/watch?v=6-ZSXB3KDF0 (https://www.youtube.com/watch?v=6-ZSXB3KDF0)

Edit: that is if you are going to post before giving Dave a chance to start the topic where he will add his initial comment like:

Quote
The 6 month test results for the Solar Roadways Solaroad.nl solar bike path project in the Netherlands are in. Dave compared the results to three local rooftop solar system and debunks the recent media reports that the project produces more power than was expected and that the solar roadway are now viable as a result.
And which country is doing Solar Roadways right? - South Korea!

But with the appropriate links he decides to place in the topic as well.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 13, 2015, 06:37:15 am
Edit: that is if you are going to post before giving Dave a chance to start the topic where he will add his initial comment like:

In this case I forgot  :palm:
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: coppice on May 13, 2015, 08:42:28 am
While the South Korean approach looks far more sane than the Dutch approach, I wonder how effective even that will be. These things have quite a long payback time, so the structure needs to stand with only low cost maintenance for many years. If you compare this to similar structures, like bike sheds and bus stop shelters, how many of those operate for 25 years without much rework? If the South Korean scheme provided a continuous shelter against the rain for cyclists, it would offer side benefits which have real value to the users. What they have done seems to be enough to provide some shelter from the sun on a hot day, but all those gaps are still going to get you very wet in the rain.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: mullecy on May 13, 2015, 11:26:49 am
I agree with 90% of what you said, but I think that there are mistakes in you calculations. The first one is taking 50% of one year production for that 6 months period mainly in winter. I suggest you look at results from neighbors as a reference and you'll find that 30% is a better estimate. The expected power is not 25Wh/m2 on that period but between 15 and 20. So 24.5 is significantly more. The second problem I have in your results is that it's all based on your estimation of the surface of the road. Any significant error there will change your results a lot. As a conclusion I'll say that yes, the results are actually better than expected, but that doesn't mean it's a good idea. I prefer the Korean way. But I also think that panels in the middle of a freeway is not that good, because you have to close lanes for maintenance: panels on sides would be better but would increase the width of the freeway.

...

If you sum the production of 6 months from your first neighbor http://pvoutput.org/aggregate.jsp?p=0&id=24667&sid=22510&t=m&gs=0&v=0&o=date&d=desc (http://pvoutput.org/aggregate.jsp?p=0&id=24667&sid=22510&t=m&gs=0&v=0&o=date&d=desc) , from November 2014 to April 2015 included you get 743.15kWh. If you do the sum for a full year from May 2014 to April 2015, you get 2354.88kWh. So for 6 months mainly in winter you get only 31.56% of the production of one year. So For panels in the same region in the same period you should get a similar result. So the expected production for 6 months in winter is 15.8 and not 25. For the second reference it's 32.8% giving 16.4 and for the third it's 30.08% giving 15kWh/m2... The differences from one neighbor to another one depends on the orientation of the panels. Panels "more vertical" can produce more in winter (with sun low above horizon) but will loose efficiency in summer. Horizontal panels are affected a lot in winter because sun barely illuminates them. The 15kWh/m2 is for panels at an angle (on roofs). So for horizontal panels, the reference expected production in winter is even lower than those 30%. Doing almost 25 means that the year production should be over 75kWh/m2 and may be close to 100kWh/m2
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: max_torque on May 13, 2015, 12:11:34 pm
Ignore everything that doesn't matter: i.e.

Just take the total cost of the solar cycleway and divide it by the total energy generated over the test period.

Do exactly the same for the three local roof top systems.


Let us know the results!  :popcorn:
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Jay_Diddy_B on May 13, 2015, 12:12:41 pm
Hi,

In the area of Canada where I live the electricity is sold by Ontario for 8, 12 or 16 cents per kWh. The price depends on the time of day.

With the solar roadways at 25 kWhr/m2 per year. This puts a retail value of the electricity generated between $2.00 and $4.00 per m2.

The Ontario Power Authority, in their wisdom  :-// , pays about $0.80 per kWh for solar generated electricity, put back into the grid. I think it is terrible to create this false economy by paying several times the retail price of the electricity.

Even at the $0.80 level, the solar roadway only generates $20.00 / m2.

This high cost renewable energy is causing increased costs to consumers:

In addition to the forecasts in the Ministry’s LTEP
and contained in Figure 4, in April 2010, the OEB
completed an analysis predicting that a typical household’s
annual electricity bill will increase by about
$570, or 46%, from about $1,250 in 2009 to more
than $1,820 by 2014. More than half of this increase
would be because of renewable energy contracts
.

Where is the return on investment?

I guess this is 'tax dollars at work'   :palm:

Regards,

Jay_Diddy_B
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: mullecy on May 13, 2015, 12:39:01 pm
Ignore everything that doesn't matter: i.e.

Just take the total cost of the solar cycleway and divide it by the total energy generated over the test period.

Do exactly the same for the three local roof top systems.


Let us know the results!  :popcorn:

Sure but I prefer to base conclusion on accurate calculations instead of big mistakes...
Saying that they expected 50kWh/year = 25 for 6 months is a serious one.
I proved that it is actually under 15kWh (because horizontal panels are even more inefficient in winter compared to roof/angled ones). So expecting under 15 and getting 24.5 is a huge upgrade...

As Dave gives lessons on how to do calculations properly, I expect proper ones from him...   :-/O

Concerning the financial part you can't base conclusions on bad results. We need 1 year to establish things. All we can do now is to extrapolate the results on those 6 months to 1 year. And the problem is that Dave thinks that what was produced in winter will be 50% of the year. I proved that it's less than 30%. Conclusion to get a full year estimate of the produced power, you have to multiply the 3000kWh produced by 3 or 4 and not by 2... This makes a big difference.

I don't say that this will make the solar road useful, efficient... but doing calculations badly will only give credit to the supporters of the thing.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 13, 2015, 01:08:22 pm
Saying that they expected 50kWh/year = 25 for 6 months is a serious one.
I proved that it is actually under 15kWh (because horizontal panels are even more inefficient in winter compared to roof/angled ones). So expecting under 15 and getting 24.5 is a huge upgrade...
As Dave gives lessons on how to do calculations properly, I expect proper ones from him...   :-/O

It a decent approximation over a half of the yearly curve. Yeah it's likely to be a bit lower, but it's decent ballpark approximation. The April result was a particularly strong one compared to the last cycle, and Nov was up a bit too from last cycle.
What I did was ok for a ballpark calculation I think without confusing things with a fudge factor.

Quote
Concerning the financial part you can't base conclusions on bad results. We need 1 year to establish things.

It's going to make bugger-all difference to the final analysis whether it's 50kWh / sqm or 70kWh / sqm when the system system cost is many times the cost of a rooftop installation! And that's not factoring in potential reduced life due to the environment it's placed in and further loss due to further wear etc.

Quote
Conclusion to get a full year estimate of the produced power, you have to multiply the 3000kWh produced by 3 or 4 and not by 2... This makes a big difference.

By their own estimates it's going to be 70kW / sqm / year. That's a best case factor of 2.8 times, not 3 or 4 like you are claiming.
My factor of x 2 will be more realistic factor in the long run given the stuff I mentioned above.

Also, a local resident mentioned it was closed for a good lot of the winter because of the glass breakage, so probably not a full 6 month wear cycle.

But when it all comes down to it, faffing over 10's of percent on a demonstrably stupid idea, still makes it demonstrably stupid.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 13, 2015, 01:16:17 pm
Quote
So expecting under 15 and getting 24.5 is a huge upgrade...
Maybe your calcs are correct but IIRC the solar pathways people said themselves it was only a bit more than expected.

Correct.
I don't doubt they might get 70kWh out of it come the full year, which is what they calculate based on whatever model they are using. But meh, still doesn't make it the least bit viable.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 13, 2015, 01:23:33 pm
faffing over 10's of percent on a demonstrably stupid idea, still makes it demonstrably stupid.

This.

10% (or even 50%!) less stupid is still very stupid when your starting point is "one of the stupidest ideas ever".

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 13, 2015, 01:25:45 pm
In the area of Canada where I live the electricity is sold by Ontario for 8, 12 or 16 cents per kWh. The price depends on the time of day.
With the solar roadways at 25 kWhr/m2 per year. This puts a retail value of the electricity generated between $2.00 and $4.00 per m2.

Incorrect. The expected result is 70kWh/year at best by the looks of it. Say a 50-70kWh/year range depending upon factors, not including any loss with age which is likely to the higher than rooftop solar which has much less harsh physical conditions.
But even at say $12 / sqm return a year, what is the payback period?

Quote
Even at the $0.80 level, the solar roadway only generates $20.00 / m2.

Correct that to $56 sqm.
Still pretty dismal.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 13, 2015, 01:27:02 pm
10% (or even 50%!) less stupid is still very stupid when your starting point is "one of the stupidest ideas ever".

I think I said as much in the video?
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 13, 2015, 01:49:45 pm
10% (or even 50%!) less stupid is still very stupid when your starting point is "one of the stupidest ideas ever".
I think I said as much in the video?

Not strongly enough. These people need a good slapping.

Let's take the 'solar' out of the equation for ten seconds. The idea that roads should be made of smooth, transparent glass is so monumentally stupid that you'd have to have your brain completely removed to even consider it. Apart from not being able to brake; the amount of grit and dirt that falls from passing lorries would grind the surface into unusability in a few weeks. Gorilla glass or not. There's also wind and Saharan dust (http://www.express.co.uk/news/nature/467901/It-s-not-April-Fools-quite-yet-Unexplained-dust-covers-cars-in-UK-blown-in-from-Sahara) to provide some free abrasives if the lorries don't make the quota.

The fact that simple math can also prove that 'solar' won't ever work is just icing on the stupid cake. The road would probably never even pay for all the millions of wires/batteries/inverters that you'd need to attach to it as infrastructure. Don't forget to add the whole new security force you'd need to create to stop Romanians from stealing the wires... (yes, cable theft is a major problem in Europe)


The only way it could possibly be even stupider is if you added some solar powered lamps to shine on the road at night and increase the output.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 13, 2015, 01:56:17 pm
10% (or even 50%!) less stupid is still very stupid when your starting point is "one of the stupidest ideas ever".
I think I said as much in the video?
Not strongly enough. These people need a good slapping.

Guess I was tired after the first two videos.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 13, 2015, 01:57:42 pm
I think I said as much in the video?
Not strongly enough.
Guess I was tired after the first two videos.
Yes, I remember you were a lot meaner in the first video.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 13, 2015, 01:58:16 pm
Let's take the 'solar' out of the equation for ten seconds. The idea that roads should be made of smooth, transparent glass is so monumentally stupid that you'd have to have your brain completely removed to even consider it.

Absolutely. Got to be a dozen show-stoppers in this if you think about it enough.
I didn't touch that aspect because it's not something I can easily refute with actual data and calcs.
ThunderfOOt did some of that.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: ali_asadzadeh on May 13, 2015, 02:01:21 pm
I have another crazy idea to add to this bulshit, they can use wireless charging tech to charge the cars moving on top of the road! :-DD
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 13, 2015, 02:18:05 pm
(http://wac.450f.edgecastcdn.net/80450F/screencrush.com/442/files/2012/09/dumb-and-dumber-2.jpg)

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: mullecy on May 13, 2015, 02:26:40 pm
It a decent approximation over a half of the yearly curve. Yeah it's likely to be a bit lower, but it's decent ballpark approximation. The April result was a particularly strong one compared to the last cycle, and Nov was up a bit too from last cycle.
What I did was ok for a ballpark calculation I think without confusing things with a fudge factor.

No and again this is where you are terribly wrong. 50% is not "ballpark" it's completely wrong. In winter sunlight time is much shorter than in summer in NL and the Sun is not high at all.

You took figures from neighbors. Why didn't you use these figures to check that ?
I did it and found 30%.
And those figures are for panels on roofs that are less badly impacted by sun being low in winter because they are higher and not shadowed by vegetation and buildings around and because of the angle. Even at dusk and dawn those panels produce power while horizontal ones don't.
So in winter (the period from november 14 to may 15 is mostly winter) the production may even be lower than 30% and maybe 25%.
So if they did 25 and that's 25%-30% of the year production, then one year will actually be 80-100kWh/m2
That's much better than the 50-70kWh/m2 they expected.

I agree that these solar roads are stupid, but this is not a reason to say that 25-30% and 50% are almost the same thing...

You did all your calculation with 2 or 3 digits but you have 40% error on the first step of it. Don't you think that's an issue ?
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: rsjsouza on May 13, 2015, 03:51:29 pm
BTW, I saw the Solar Roadways wiki page (https://en.wikipedia.org/wiki/Solar_Roadways) has links to Dave's videos and added this last one.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: m100 on May 13, 2015, 05:20:41 pm
As for the 50% ballpark for six months,  in the UK, not too dissimilar to the Netherland in cloud cover and insolation, the Wh output per month for the five months of May to September is on average about 4x what it is for the 7 months October to April.  That's a figure for a handful of offline systems of a few hundred Watts that have been running for about a decade now, all unshaded, all on tilt mounts optimised for maximum output in winter.

Solar Roadways are a really crappy idea, they are the kind of thing the EU loves to fund.   You cannot ever beat a nice big nuke, coal or gas fired power station for suppling energy regardless of the weather.  Solar and wind are causing significant power system transmission issues in Europe, and are severely damaging to the economics of the conventional generation that will always be needed for condtions of cloud cover and large static high pressure systems commonly encountered over Northern Europe. 

Nuclear Power  :-+

Solar & Wind   :--
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Jeroen3 on May 13, 2015, 06:17:35 pm
Mayve we should be paving dikes with solar panels to become profitable.  :P

Also, the website states the panels are 2.5 x 3.5 meter. Does that change the numbers much?

On a sidenote:
The pilot is €3 million euro (50% government funded), and they expect a production road (not this one) to pay back in 15 years.
In about 5 years they hope to start producing to pave more roads.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on May 13, 2015, 06:37:53 pm
And the prize for best lede on Solar Roadways goes to:

http://breakingenergy.com/2015/05/13/solaroad-performs-better-than-expected-remains-pointless/ (http://breakingenergy.com/2015/05/13/solaroad-performs-better-than-expected-remains-pointless/)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fsck on May 13, 2015, 06:46:11 pm
considering they could've done the math easily beforehand, I really wonder if they believe it was a success or if they're actually delusional.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: vlad777 on May 13, 2015, 06:50:03 pm
Three layer solar cell has maximum theoretical efficiency of 45% and infinite layer has 80% .
So instead of crying about this, why don't we make use of this fact.
I am proposing a greenhouse made out of one-layer solar cell that is transparent to blue light that plants like. (and far IR)
And if earth needs for energy are going to come from solar,
 than I predict that all of arable land will be covered in these greenhouse-power plants.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Jeroen3 on May 13, 2015, 07:32:25 pm
That doesn't work because most greenhouses have gas engine generators for heat, co2 and power production already. Why would they want expensive solar panels?
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: vlad777 on May 13, 2015, 07:41:33 pm
To ditch the gas engine and also there may be some surplus energy.

Edit, gasoline is going to run out. Also you have to pay for it constantly.

(http://www.viridiansolar.co.uk/Assets/Images/Technical/energy%20spectrum%20max%20efficiency_small.jpg)

I am including this picture to illustrate that there is enough near IR to convert to far IR (heat).
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: max_torque on May 13, 2015, 08:07:34 pm
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Monkeh on May 13, 2015, 08:24:49 pm
Packet B please, I'm sure they're far superior.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: eneuro on May 13, 2015, 09:07:15 pm
The expected power is not 25Wh/m2 on that period but between 15 and 20. So 24.5 is significantly more.
It is  :bullshit: while make easy calculation:
3000kWh per 6 months, great 3MWh wow  :-DD
BUT: 6months= 6*30.5 days= 183 days
so we get: 3000 kWh / 183 ~16 kWh/day
Is it 122 m2 instalation, so we get: 0.131kWh/m2/day  :palm:
Now lets assume those bloody roads worked for those "great" results 8 hour a day, than we get: 0.016kWh/m2/hour = 16 Wh/m2/hour :blah:  :wtf:
I wish I made mistake, but probably not :popcorn:
Update: I've forgot hour in kW in a few places, but doesn't change to much.. corrected now.

Dave have on his 3000kWh per 6 months, but ~16 Wh/m2/hour it is nothing and people riding bicycle will easy save such amount of energy, by... driving 1km/h slower or slower on this path  :-DD

BTW: Forgot to mention that even using not cheap electricity cost in my country it looks like those "solar roads" earned ~0.80 $ /month/m2  :-DD
Is it a joke?  :-DMM
(http://s16.postimg.org/cuqid6g6d/solaroad_nl.png)

In comparision another data:
This cheap savonius wind turbine output annual 1752 kWh (per 12 months I guess) using ONLY 9m2 wind swept area,
so we have 16kWh/m2/month  and 146kWh/month ~5kWh/day assuming small investment not so bad  :-+
http://www.uvm.edu/extension/cropsoil/wp-content/uploads/savonius_windpower_report.pdf (http://www.uvm.edu/extension/cropsoil/wp-content/uploads/savonius_windpower_report.pdf)

They claim 2 years payback period invested ~1000$ if we consider only materials used for steel savonious wind turbine  8)
(http://s16.postimg.org/t04y088rl/savonius_windpower_report_payback_period.jpg) (http://postimg.org/image/t04y088rl/)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: NANDBlog on May 13, 2015, 10:10:53 pm
On a sidenote:
The pilot is €3 million euro (50% government funded), and they expect a production road (not this one) to pay back in 15 years.
In about 5 years they hope to start producing to pave more roads.
I hope they dont. This solar roadways payback questions are like asking people how much time does it for a church to pay back. They dont care they do it because they believe in it.
It is like in the 21 century we do engineering and science based on what we believe in, screw logic. Solar roadways, mars one, perpetuum mobiles, and indiegogo revolutionary gadgets.

BTW, seeing 3 Daves waving hands at the same time, in black tee  :)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Someone on May 14, 2015, 01:04:38 am
Edit: that is if you are going to post before giving Dave a chance to start the topic where he will add his initial comment like:
Quote
The 6 month test results for the Solar Roadways Solaroad.nl solar bike path project in the Netherlands are in. Dave compared the results to three local rooftop solar system and debunks the recent media reports that the project produces more power than was expected and that the solar roadway are now viable as a result.
And which country is doing Solar Roadways right? - South Korea!
There is roadside solar in Melbourne, pretending to use some space on top of a reclaimed rubbish dump site.
https://www.google.com.au/maps/@-37.768334,144.809395,3a,75y,128.35h,89.59t/data= (https://www.google.com.au/maps/@-37.768334,144.809395,3a,75y,128.35h,89.59t/data=)!3m4!1e1!3m2!1sYgz61tw1WlDq0VVXVQjnUA!2e0!6m1!1e1
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 14, 2015, 01:10:33 am
Also, the website states the panels are 2.5 x 3.5 meter. Does that change the numbers much?

They don't look 2.5m wide to me.

(https://gallery.mailchimp.com/fc23dec47019a23d70031492e/images/4cd9e703-944f-4f93-bfc1-19c9a62b70f0.jpg)

They might have changed it from the initial prototype from the ones used in the actual pathway. I forget how I came to the 1.75m figure in the previous video.
Bigger than I expected would mean they aren't as good as I calculated.

EDIT: David2 and I just did a test with a measuring tape, and 2.5m seems too wide. Also, the ratio of the panel dimensions doesn't quite fit the 1:1.4 of 2.5m x 3.5m
In any case, bigger makes the calcs for the output worse.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 14, 2015, 01:18:05 am
No and again this is where you are terribly wrong. 50% is not "ballpark" it's completely wrong. In winter sunlight time is much shorter than in summer in NL and the Sun is not high at all.

Fine, I was wrong to make the 50% ballpark assumption, happy?

Quote
You took figures from neighbors. Why didn't you use these figures to check that ?
I did it and found 30%.

Their own figures indicate a ratio of 2.8 based on my area measurements, not 2.0 as I used. That's about 35%.

Quote
So if they did 25 and that's 25%-30% of the year production, then one year will actually be 80-100kWh/m2
That's much better than the 50-70kWh/m2 they expected.

Their own estimates are and I quote
Quote
"If we translate this to an annual yield, we expect more than the  70 kWh per square meter per year, which we predicted as an upper limit in the laboratory stage."
If it was 100kWh they would be damn well crowing about it! So most likely it's just a smidgen more than 70kWh.

But again, I mentioned this in the video, even if it was double what they expected it's still useless from a cost perspective.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 14, 2015, 03:34:07 am
My own bicycle is 1.75 m and attempting to calculate the track width against the rightmost fully visible bicycle (with blue coat on rack) assuming it too is 1.75m leads me to approx 2m. If it is 2.5m wide then that would be a freakish long bicycle.

Yep, about 2m popped out for us too. 2.5m wide seems way too wide.
If it is 2m then 1.75m isn't too bad because the cell isn't the full width.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: BobC on May 14, 2015, 07:48:47 am
It's customary to embed the video on the first post:

Edit: that is if you are going to post before giving Dave a chance to start the topic where he will add his initial comment like:

But with the appropriate links he decides to place in the topic as well.

Hey, I'm just glad I remembered to use the correct subject line.  It did get folks like you here to do the next step.

Thanks!
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: firewalker on May 14, 2015, 08:35:22 am
Dave, did you calculate that the 100% of the panel surface produces power? What is the effective area? 70%? If so, the kwh/m2 could be slightly better, is the area of the roof top panels show on the data is the effective area.

Alexander.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 14, 2015, 08:46:07 am
Dave, did you calculate that the 100% of the panel surface produces power? What is the effective area? 70%? If so, the kwh/m2 could be slightly better, is the area of the roof top panels show on the data is the effective area.

I mentioned in the video IIRC that I used 100% area for both the solar pathway and the solar panels, so any unused area on both should be similar and hence comparing apples with apples.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 14, 2015, 10:11:55 am
Dave, did you calculate that the 100% of the panel surface produces power? What is the effective area? 70%? If so, the kwh/m2 could be slightly better, is the area of the roof top panels show on the data is the effective area.

Which part of "ballpark figures" is confusing? :palm:

Even if we add another 10% it's still not enough to take it off the list of "top-10-stupidest-ideas-ever".

To take it off that list you'll need a 1000% improvement in output, not 10%. Even so it'll still be on the "top-100-stupidest-ideas-ever" list.  (Lorries driving on glass for 20 years without any damage at all? Really?)

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: quarros on May 14, 2015, 10:37:29 am
I forget how I came to the 1.75m figure in the previous video.

There was one forum member who went there for check (frvisser) and he posted about it in the forum: https://www.eevblog.com/forum/blog/eevblog-681-more-solar-roadways-bullshit!/msg546105/#msg546105 (https://www.eevblog.com/forum/blog/eevblog-681-more-solar-roadways-bullshit!/msg546105/#msg546105)
One tile is 170X270 cm.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 14, 2015, 11:50:21 am
There was one forum member who went there for check (frvisser) and he posted about it in the forum: https://www.eevblog.com/forum/blog/eevblog-681-more-solar-roadways-bullshit!/msg546105/#msg546105 (https://www.eevblog.com/forum/blog/eevblog-681-more-solar-roadways-bullshit!/msg546105/#msg546105)
One tile is 170X270 cm.

Ah, now I remember that, thanks. Still don't remember how I calculated it initially, but it was close to spot on.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: JoeO on May 14, 2015, 12:14:37 pm
Maybe we need videos on "Worst Case Analysis" and one on "Best Case Analysis" that is separate from the solar roadways project.

It is obvious that some people do not understand these concepts.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: mullecy on May 14, 2015, 12:27:51 pm
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Read my answer... This is what I did. But I guess reading more that one line and quoting it out context is all you can do.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: JoeO on May 14, 2015, 12:36:31 pm
50 years ago my father gave me a Knight Kit solar powered radio.  I was so impressed that I investigated solar power.  50 years ago, financially practical solar power was just around the corner.
50 years later, today, it is still just around the corner. 
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Monkeh on May 14, 2015, 12:53:04 pm
Dave, your obsession with comparing this to roof top solar made you completely miss the point of the project.

Local governments own a lot of property, including many paths. They spend quite a bit of money building and maintaining them. Solar PV is getting cheaper. They can only install so much rooftop solar, and the way budgets work they often can't just take money from the paving budget and spend it on roofs. Having the option to install less efficient but still useful solar paving will allow them to install PV capacity that they would otherwise not be able to.

I think you completely missed the point.

Why install amazingly expensive, less effective solar roads when they could put solar panels up on posts next to the road for less money and more output?
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 14, 2015, 12:54:32 pm
Local governments own a lot of paths. They spend quite a bit of money building and maintaining them.

They're going to spend an awful lot more building these.

They're also going to spend an awful lot more maintaining them - especially when kids find they can smash them for fun.

Bottom line: There's no way a bit of 'free' electricity can ever make up for any part of this steaming turd of an idea. If you want to help the world then invest those billions of dollars you'd spend on this  in fusion research instead.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Monkeh on May 14, 2015, 01:10:53 pm
They're going to spend an awful lot more building these.

That's the thing, not really. I work in the water industry, and so I know a bit about the costs to do works in public areas. Most of the cost is not the materials, it's labour, ensuring that the work is done safely, managing traffic and diversions etc. Because of that digging a 1m square hole can easily cost €5-10k. The cost of the replacement 1m square paving surface is a fraction of that.

But you don't need to dig a 1m² hole, or replace the paving surface.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Monkeh on May 14, 2015, 01:41:24 pm
But you don't need to dig a 1m² hole, or replace the paving surface.

What... are you on about? It's an example of the costs involved of doing works in a public area. The costs of actually digging the hole and the materials needed to re-cover it are negligible, that's the point. It's the same when you want to re-surface or build a new path somewhere. Most of the cost is not the materials.

I'm on about not needing to replace pavements with stupid solar pavements.

Okay, sure, a lot of the expense is indeed in the work, not the material, but why spend money on crap solar in the ground when you can do it properly for less?
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Jeroen3 on May 14, 2015, 02:58:19 pm
This was a pilot project. An experiment. Government funded.
No company nor individual will ever pay for non-profitable solar roads from non-pr budget. Or at least, healthy companies shouldn't.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: DanielS on May 14, 2015, 03:04:32 pm
Dave, your obsession with comparing this to roof top solar made you completely miss the point of the project.
Dave's point is simple enough: putting solar panels in the ground is many times more costly and half as efficient. It simply does not make economic sense. Raised solar panels cost half as much to install and produce twice as much power.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 14, 2015, 05:31:43 pm
Dave's point is simple enough: putting solar panels in the ground is many times more costly and half as efficient. It simply does not make economic sense. Raised solar panels cost half as much to install and produce twice as much power.
...
c) Will need a fraction of the maintenance.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: miguelvp on May 14, 2015, 05:38:41 pm
This was a pilot project. An experiment. Government funded.
No company nor individual will ever pay for non-profitable solar roads from non-pr budget. Or at least, healthy companies shouldn't.

The problem with Government funded is that the money comes from taxes that could have produced good returns instead of votes.

I would think the approval rate for that project as perceived by the general public is good and green and the return is votes.
So mission accomplished!
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: max_torque on May 14, 2015, 06:58:39 pm
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Read my answer... This is what I did. But I guess reading more that one line and quoting it out context is all you can do.

I have ready you original answer, and like a lot of people who seem to think solar roadways are viable, you are missing the critical point, which is:

THE ABSOLUTE AMOUNT OF ENERGY PRODUCED BY A SOLAR ROADWAY IS NOT IMPORTANT!

The only thing that is important is:

THE COST OF THE ENERGY PRODUCED ON A $/kWHr BASIS.


So, you have a cloudy year and  your solar road way only makes 100kWhrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughly 200kWhrs.

So you have an amazingly "sunny" year and you solar road way makes a massive 100,000kWHrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughtly 200,000kWHrs.


In ALL cases, the higher efficiency (tilted panels, thinner, cleaner glass)  and lower installation costs means that the conventional roof top solar installation will have something like a 4x faster ROI than your solar roadway.  In our Capitalist economy, that is the only thing that matters!
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: eneuro on May 14, 2015, 07:38:18 pm
In ALL cases, the higher efficiency (tilted panels, thinner, cleaner glass)  and lower installation costs means that the conventional roof top solar installation will have something like a 4x faster ROI than your solar roadway.
Hybrid solar PV & thermal solar & savonius wind turbine is better choice while beter exploits weather conditions-cloudy windy days for savonious and clear sky for thermal solar with a few time better efficiency than solar PV, which are good to power up home electronic in more efficient energy harversting system like solar thermal and savoius wind turbines  ;)
https://www.youtube.com/watch?v=6JL4q02gX7g (https://www.youtube.com/watch?v=6JL4q02gX7g)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: MauriceS on May 15, 2015, 03:07:41 am
BTW, I saw the Solar Roadways wiki page (https://en.wikipedia.org/wiki/Solar_Roadways) has links to Dave's videos and added this last one.
It got removed because: "When the guy becomes a member of the national academy or wins a pulitzer or something then I can see his own blog qualifying for an exception to the blog rule, at least to the extent that he has certain opinions based on original speculation-based guesswork. "

The editors don't get ENGINEERING practices, where one can make guestimates.
Solar Roadways Wiki Talk (http://en.wikipedia.org/wiki/Talk:Solar_Roadways)

And also because SR didn't release any of their results (which they never will): "To my knowledge, the details of Solar Roadways' R&D are still proprietary, rendering any "detailed analysis" dependent entirely on speculation. It might be generally informed, with knowledge of the current state of on the shelf technology, but he has to guess what on the shelf technology might be used, and he has to assume the company has not invented any new components, materials, or combinations. Informed speculation is still speculation. In short, this guy is engaged in educated guessing on his blog, and that has ZERO WEIGHT."
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: bitwelder on May 15, 2015, 05:20:59 am
It got removed because: "When the guy becomes a member of the national academy or wins a pulitzer or something then I can see his own blog qualifying for an exception to the blog rule, at least to the extent that he has certain opinions based on o
So, do we need the calculations published in an article on some printed magazine to make it acceptable?
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 15, 2015, 05:33:26 am
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Read my answer... This is what I did. But I guess reading more that one line and quoting it out context is all you can do.

Your calculations have no relevance to what max_torque  is saying.
In my video I got the data from the solar road and nearby rooftop solar system and compared the output per square area over the exact same period. Rooftop has has double the output of SolaRoad, and that's all that really matters. You could have used a weeks worth of data and got the same result.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 15, 2015, 05:35:08 am
50 years ago, financially practical solar power was just around the corner.
50 years later, today, it is still just around the corner.

Huh?  :-//
The payback period on my system is in the order of 5 years.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 15, 2015, 05:36:13 am
Dave, your obsession with comparing this to roof top solar made you completely miss the point of the project.
Dave's point is simple enough: putting solar panels in the ground is many times more costly and half as efficient. It simply does not make economic sense. Raised solar panels cost half as much to install and produce twice as much power.

Yup, that!
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 15, 2015, 05:46:42 am
BTW, I saw the Solar Roadways wiki page (https://en.wikipedia.org/wiki/Solar_Roadways) has links to Dave's videos and added this last one.
It got removed because: "When the guy becomes a member of the national academy or wins a pulitzer or something then I can see his own blog qualifying for an exception to the blog rule, at least to the extent that he has certain opinions based on original speculation-based guesswork. "

Wow, I thought the inclusion of criticism in that wiki article was well placed by whoever it was. Given the number of people speaking out against Solar Roadways it certainly deserves a "Controversy" section highlighting legitimate complaints. You could easily add a dozen blogs and articles critical of Solar Roadways.

Quote
(A) its a blog, (B) its still speculation because he's guessing as to the particulars. We don't publish speculation. If you've got heavy hitters expressing dubious skepticism, we should be able to add fact they think so that in NPOV)

How is the world's biggest electrical engineering channel with 240,000 subscribers and 300,000 views on the critique video not "heavy hitting"?
What do they want, and official article in the IEEE?
The fact that there are many critiques of the project is noteworthy enough to at least includes links to them and mention them.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Monkeh on May 15, 2015, 10:03:43 am
How are you going to take money from the paving budget and transfer it to building maintenance?

The same way you'll increase the budget for materials by in excess of an order of magnitude.

Seriously, stop dreaming.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Monkeh on May 15, 2015, 12:06:41 pm
How are you going to take money from the paving budget and transfer it to building maintenance?

The same way you'll increase the budget for materials by in excess of an order of magnitude.

Seriously, stop dreaming.

You have no idea how budgeting works in large organisations, do you?

Ill-educated idiots ask for money for poorly thought out ideas and get it?
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: MauriceS on May 15, 2015, 02:05:32 pm
I'm amazed how many so-called science magazines and websites are publishing this as the best since sliced bread - and they don't even do their due diligence. They just publish the Solar Roadways information the truth, but it isn't more than an advertisement.

And every positive publicity gets linked on the SR site as that...

And looking at the comments, everyone who is in favor of it, turns their brains off. It's solar, it's renewable, so it must be good, and they do not listen to any of the well thought out arguments.

But I doubt w'll never see actual true numbers from Solar RoadWays... I'm sure their lawyers would say - "If you publish those - you'll have a class action suit on your hands!"
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: mullecy on May 15, 2015, 02:12:47 pm
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Read my answer... This is what I did. But I guess reading more that one line and quoting it out context is all you can do.

I have ready you original answer, and like a lot of people who seem to think solar roadways are viable, you are missing the critical point, which is:

THE ABSOLUTE AMOUNT OF ENERGY PRODUCED BY A SOLAR ROADWAY IS NOT IMPORTANT!

The only thing that is important is:

THE COST OF THE ENERGY PRODUCED ON A $/kWHr BASIS.


So, you have a cloudy year and  your solar road way only makes 100kWhrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughly 200kWhrs.

So you have an amazingly "sunny" year and you solar road way makes a massive 100,000kWHrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughtly 200,000kWHrs.


In ALL cases, the higher efficiency (tilted panels, thinner, cleaner glass)  and lower installation costs means that the conventional roof top solar installation will have something like a 4x faster ROI than your solar roadway.  In our Capitalist economy, that is the only thing that matters!

Of course you didn't read all I wrote because I repeated more than once that I think those solar roads are bad ideas.
It's just that Dave spend almost half of this video saying that "they didn't beat the expectations" and that "it's all marketing"...
Well that first half of the video is just wrong. Sorry.

I'm a big fan of Dave and when I looked at the video the first time I was incredibly disappointed because he says that he took figures from neighbors at the same period of time... but ignored them to evaluate if the expectation are met or not.  :wtf:
(But now he added a comment in the video saying that it's less than 50%... thx Dave  8) )

But I also said that this doesn't change the fact that loosing 50% efficiency compared to panels on roofs plus the cost make this a bad idea. Unless you are near the equator because in that case you should have horizontal panels anyway, but in poor countries, putting high value panels on the ground is the best way to see them disappear... Conclusion: bad idea in all cases.

Another point that is not linked to the video is that panels on houses is not the panacea for many reasons: first the installation cost is not that low because for a given total surface you'll need many houses any many contractors... You'll also need an inverter per house... many elements will be duplicated.
Big farms of solar panels are better to my opinion (if it's not stealing land from agriculture).

You'd better use your roof to make hot water so you use less hydrocarbons when you take a shower.
And if you don't live in Sidney you may also use that to heat your house in winter and significantly reduce your C02 emissions.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: DanielS on May 15, 2015, 03:31:55 pm
"Informed speculation is still speculation. In short, this guy is engaged in educated guessing on his blog, and that has ZERO WEIGHT."
Since SR is just an integrator project, the likelihood of SR discovering fundamentally new materials or components that might change the outcome of speculations based on off-the-shelf parts is abysmally low. The only thing that makes SR remotely feasible is the availability of relatively inexpensive off-the-shelf parts and materials, courtesy from the power, semiconductor and material industries that invests billions of dollars into it each year in their respective fields of interest.

I doubt SR would have a class-action on their hands if they were forced to admit the truth and publish the raw data for anyone to analyze. But their funding/play-money would likely dry up very quickly. For now though, they hide themselves behind the questionable excuse that off-the-shelf materials and components are somehow not representative of what they are working with.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: rsjsouza on May 16, 2015, 11:06:01 am
I think that is very pertinent to this and other discussions:
http://www.newyorker.com/humor/borowitz-report/scientists-earth-endangered-by-new-strain-of-fact-resistant-humans (http://www.newyorker.com/humor/borowitz-report/scientists-earth-endangered-by-new-strain-of-fact-resistant-humans)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: abebarker on May 17, 2015, 01:04:15 am
I, for one, think that solar roadways would be an excellent idea. I don't mean embedding PV cells in the surface, that is just foolishness.

Correct me if I am wrong but the very best possible solar collector, in theory, is a black body at 0.0K. It absorbs every wavelength of radiation. Although we can not have a roadway cooled to 0.0K or even 0.0C in practice, because of the condensation, we can cool it down in certain situations.

Knowing what the ideal solar collector is leads me onto another train of thought; How viable is it to pull the heat out of something to feed a heat engine? A common heat pump has a COP of 3-4. For every 1 unit of energy you put in you get 3-4 units of energy out.

The next question becomes; Is it possible to feed a heat engine with the output of a heat pump?
The answer is; Yes but it will not be a viable source of heat until the efficiency of the engine exceeds the inverse of the efficiency of the heat pump. Which is not easy because the efficiency of the engine increases with temperature difference where as the efficiency of the heat pump decreases with temperature difference (in the positive direction).

Solar roadways may become practical with the development of high efficiency, low differential heat engines, like the super critical waste heat engines or dissociable gas turbine engines.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: jwm_ on May 17, 2015, 01:25:19 am
Knowing what the ideal solar collector is leads me onto another train of thought; How viable is it to pull the heat out of something to feed a heat engine? A common heat pump has a COP of 3-4. For every 1 unit of energy you put in you get 3-4 units of energy out.

That's not what COP means, it means you can burn a btu of energy and pump 3-4 btus of heat energy with it. It does not produce any energy, just pumps it from one place to another while needing independent energy to make it run. All this energy has to already exist for it to be pumped around. And it is just heat that is pumped so it is not really useful energy unless what you want to do is heat something with it.

As to the amount of energy you can extract from a heat engine, it depends on the absolute difference in temperature between your hot and cold side. Solar heat engines work quite well, but in order to get the temperature differential needed to extract energy efficiently, they need parabolic mirrors to concentrate the suns rays to a single point. A black roadway may collect as much energy as a parabolic mirror of the same area, but it doesn't reach a temperature necessary for extracting any useful work from it.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on May 17, 2015, 01:36:05 am
The next question becomes; Is it possible to feed a heat engine with the output of a heat pump?
The answer is; Yes but it will not be a viable source of heat until the efficiency of the engine exceeds the inverse of the efficiency of the heat pump. Which is not easy because the efficiency of the engine increases with temperature difference where as the efficiency of the heat pump decreases with temperature difference (in the positive direction).

The answer is no.  The closest thing to what you seem to want is geothermal, where a small pump extracts enough energy at a high enough delta T to perform useful work.

Low grade heat used to power engines is difficult. 

The only technology that currently does so on a commercial basis is Organic Rankine Cycle, which is a closed circuit turbine that typically uses a refrigerant as the working fluid.  Net electric efficiencies are low at about 20-25% (highly dependent on delta T and the size of the system).  The upshot is that the maintenance costs are extremely low. 

Here's an overview of an ORC system:  http://www.epa.gov/chp/documents/meeting_100511_ronzello.pdf (http://www.epa.gov/chp/documents/meeting_100511_ronzello.pdf)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: abebarker on May 17, 2015, 06:04:50 am
That's not what COP means, it means you can burn a btu of energy and pump 3-4 btus of heat energy with it. It does not produce any energy, just pumps it from one place to another while needing independent energy to make it run. All this energy has to already exist for it to be pumped around. And it is just heat that is pumped so it is not really useful energy unless what you want to do is heat something with it.

A black roadway may collect as much energy as a parabolic mirror of the same area, but it doesn't reach a temperature necessary for extracting any useful work from it.

Yes. I agree. I will add that a heat pump not only moves those 3-4 units but it also compresses them into a smaller space i.e. it raises the temperature or increases the quality of the heat that is there.

The next question becomes; Is it possible to feed a heat engine with the output of a heat pump?
The answer is; Yes but it will not be a viable source of heat until the efficiency of the engine exceeds the inverse of the efficiency of the heat pump. Which is not easy because the efficiency of the engine increases with temperature difference where as the efficiency of the heat pump decreases with temperature difference (in the positive direction).

The answer is no.  The closest thing to what you seem to want is geothermal, where a small pump extracts enough energy at a high enough delta T to perform useful work.

Low grade heat used to power engines is difficult. 

The only technology that currently does so on a commercial basis is Organic Rankine Cycle, which is a closed circuit turbine that typically uses a refrigerant as the working fluid.  Net electric efficiencies are low at about 20-25% (highly dependent on delta T and the size of the system).  The upshot is that the maintenance costs are extremely low. 

Here's an overview of an ORC system:  http://www.epa.gov/chp/documents/meeting_100511_ronzello.pdf (http://www.epa.gov/chp/documents/meeting_100511_ronzello.pdf)

The answer is yes. It doesn't have to supply the entire input, it may only supplement it. It may take more than one stage to raise the temperature enough. It could be used for regeneration.
Is it wise to do so? That remains to be seen.

Quote
Primarily designed for utilization of waste heat with low grade temperature sources, the charts for Organic Rankine Cycle can utilize temperatures below 212 F or 100 C and up to 180 C for standard refrigerants such as R134a or R245fa.
Quote
Efficiencies utilizing low grade temperatures can be three to 15 percent utilizing the ORC system

Quote
Brayton Cycle: Primarily designed for utilization of any heat with low to high grade temperature sources, the charts for the Brayton Cycle can utilize temperatures from 88 F or 31 C and over 550 C for CO2.
Quote
Brayton Cycle with CO2 has the potential to have an overall efficiency of up to and may exceed 45 percent.
http://www.infinityturbine.com/ORC/ORC_CO2_Performance_Publication.html (http://www.infinityturbine.com/ORC/ORC_CO2_Performance_Publication.html)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on May 17, 2015, 07:13:41 am
Of course you didn't read all I wrote because I repeated more than once that I think those solar roads are bad ideas.
It's just that Dave spend almost half of this video saying that "they didn't beat the expectations" and that "it's all marketing"...
Well that first half of the video is just wrong. Sorry.

I'm a big fan of Dave and when I looked at the video the first time I was incredibly disappointed because he says that he took figures from neighbors at the same period of time... but ignored them to evaluate if the expectation are met or not.  :wtf:

Geeze, get over it  ::)
The ultimate goal of the video was to compare the output of the solar roadways to rooftop solar in the same area over exactly the same period. I didn't ignore those results!, I used them and got the final result of twice the output power of solar roadways. The rest of the video was essentially just filler to get to that point.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on May 17, 2015, 09:15:25 am
Another "lets not look at the details" article:
http://www.autoblog.com/2015/05/15/dutch-solaroad-outperforming-expectations/ (http://www.autoblog.com/2015/05/15/dutch-solaroad-outperforming-expectations/)

Personally, I hate to see the cash evaporate into Solar Roadways when better usage could be easily be found with much higher environmental impact:
I am luky to study with some African students here in Antwerp, they get to pay the high fees due to their countries being in dire need of qualified port personnel.
(note, if you have IMO qualifications, young, single and need a well paid adventure, go to Africa)

In any case, we were talking about how in most of "black" Africa (their term), outside cities, that the lack of cheap after sundown light was a major source of lack of academic achievement.
To break it down, kids wake up do chores, go to school for 4/6 hours, do more chores till sundown.
Then they have time to study - if they have light.
If you are "rich" you can pay utilities, if not use a worn out Chinese generator on expensive black market fuel the last option is to study under a street light or sign.
Apparently, using candle light is awful, very hard to read modern print (compare a 2000's book with a 1930's book to get the idea) - and candles are expensive.

So, a good idea would be a small rootop PV, around 0.5m² to charge a small battery to sun a single 12watt CFD for 6 hours.
It would have to be a "ready to use package that could be anchored solidly, with a 5m extension with the bulb at the end.
THe materials would need to be plastic, fiber glass, and other valueless on the recycling market materials.

But, they told me, "don't give them away", sell them with for a token value WITH WARRANTY, so that users get a sense of propriety.

On the commercial side, they told me that there is a huge market for small PV (barn ventilation, insect destruction, fridges, well pumps, phone charging, WIFI points, cell towers etc) that don't need to be attached to a grid, be monitored closely or have to give a set result a day. Utilities suck there like here, but what here means someone overcharging you 30$, is a 48hours cut there, with attached dead livestock/crop.

One day, someone will sort out the right package, distribution, local manufacture (big tariffs in Africa) and earn megabucks.
While we will all be here saying "Aww shuckxs, shoulda thougta that".
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 17, 2015, 10:39:47 am
So, a good idea would be a small rootop PV, around 0.5m² to charge a small battery to sun a single 12watt CFD for 6 hours.
I'm sure there's at least half a dozen TED talks on this very subject.

(Either PV or a small hand-crank...)

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on May 17, 2015, 10:52:56 am
So, a good idea would be a small rootop PV, around 0.5m² to charge a small battery to sun a single 12watt CFD for 6 hours.
I'm sure there's at least half a dozen TED talks on this very subject.
(Either PV or a small hand-crank...)
Problem is that it's talk.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on May 17, 2015, 11:17:09 am
Problem is the panels are framed in aluminium, which has scrap value as metal. As well the wire is copper so also has value. If somebody can get 50c US for stealing something off a wall, or off a rooftop, they will do it. Cardboard is worth money, and is something that people have been killed over, just to get 2kg of it.

Your panel would have to be a glass plate with amorphous film on the back, laminated with a plastic membrane on the rear, with a frame made from GRP composite. The wire would have to be copper coated steel, with fixed connectors. Electronics inside would have to use minimal copper on the board, and the battery would have to be a 12V 7Ah SLA battery ( very common here and affordable to people) to be relatively theft proof. Cost would have to be under $30, to make it affordable to people yet worth the manufacturing cost.

As I am currently in the middle of replacing manhole covers, stolen because the cast iron is worth something as scrap metal ( and the thieves get a very low price because the unscrupulous yard owners know they are stolen but still take them at a big profit), and am using GRP composite covers and frames, so as to have minimal scrap value. The thieves might get $3 for the one they stole, but a replacement cast iron is $300, excluding the fitting costs, and the GRP one was cheaper at $200, including courier charges from half way across the country. Thus I am doing the labour work, as there is no budget for this, and insurance is not worth claiming as the excess is $400, and the loss of the no claim is worth more. Thus me out with a jackhammer, chisel and pickaxe, and mixing some tilefix and bonding liquid to improve the adhesion and smooth off the process.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on May 17, 2015, 11:47:04 am
Problem is the panels are framed in aluminium, which has scrap value as metal. As well the wire is copper so also has value. If somebody can get 50c US for stealing something off a wall, or off a rooftop, they will do it. Cardboard is worth money, and is something that people have been killed over, just to get 2kg of it.

Your panel would have to be a glass plate with amorphous film on the back, laminated with a plastic membrane on the rear, with a frame made from GRP composite. The wire would have to be copper coated steel, with fixed connectors. Electronics inside would have to use minimal copper on the board, and the battery would have to be a 12V 7Ah SLA battery ( very common here and affordable to people) to be relatively theft proof. Cost would have to be under $30, to make it affordable to people yet worth the manufacturing cost.

As I am currently in the middle of replacing manhole covers, stolen because the cast iron is worth something as scrap metal ( and the thieves get a very low price because the unscrupulous yard owners know they are stolen but still take them at a big profit), and am using GRP composite covers and frames, so as to have minimal scrap value. The thieves might get $3 for the one they stole, but a replacement cast iron is $300, excluding the fitting costs, and the GRP one was cheaper at $200, including courier charges from half way across the country. Thus I am doing the labour work, as there is no budget for this, and insurance is not worth claiming as the excess is $400, and the loss of the no claim is worth more. Thus me out with a jackhammer, chisel and pickaxe, and mixing some tilefix and bonding liquid to improve the adhesion and smooth off the process.
You'll be happy to know that this is/was a big problem here too.
It was not until yard owners where threatened of having the whole yard confiscated, every speck of metal expertises and being prosecuted as the actual thieves did this slow down. But it still happens, because the metal gets loaded into trucks and taken East. But this entails lower profits and more organisation, limiting the miscreant pool.
It's not until you get a 1 million rand fine per obviously stolen item, that the yards are going to change...

I had the stealing everything issue when working on a "3 class school unit" in a container for Guinea-Bissau...
Every part had to be designed to only fit with the parts in the container and have no resale value.
In the end (before we got cancelled), the solution I found was glass fibre structure using "click one way", a bit like those annoying plastic toys that you can't open without breaking. But the actual container and the roofing still had to be standard...
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on May 17, 2015, 12:26:53 pm
That is actually in law, but between the lackluster performance of the various enforcement, sentencing and correctional services branches, and the lack of political will ( and infighting as well) nothing is done about it. If they prosecuted a few owners, and stripped them of everything, including the clothing on their backs, as proceeds of crime, and dropped them into jail nothing will happen. Cf  noted examples et al.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on May 17, 2015, 12:31:14 pm
So, a good idea would be a small rootop PV, around 0.5m² to charge a small battery to sun a single 12watt CFD for 6 hours.
I'm sure there's at least half a dozen TED talks on this very subject.
(Either PV or a small hand-crank...)
Problem is that it's talk.
In that case the problem isn't technology, it's something else (eg. thieves).
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: f4eru on May 18, 2015, 03:04:15 pm
In that case the problem isn't technology, it's something else (eg. thieves).
A technology developed without considering the environment (in a large sense) is worthless.
If you can't commercialize a product because of some external influence, it's worthless.

So you HAVE TO consider such requirements, sot ignore them. People who ignore them are not sucessful.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: adream on May 18, 2015, 05:09:36 pm
Hi Dave and EEV bods

Skeptics Guide to the Universe, a great podcast, talks about this and Daves blog post

well worth a listen

http://www.theskepticsguide.org/ (http://www.theskepticsguide.org/)

Keep up the great work Dave and David

:-)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on May 19, 2015, 04:59:45 pm
Direct link...

http://www.theskepticsguide.org/podcast/sgu/514 (http://www.theskepticsguide.org/podcast/sgu/514)

I was listening to it today, but got pipped to the post.........
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Stebanoid on August 18, 2015, 05:53:03 am
"Technology of the future" from the BBC Science Hour.
At 11:05 here
http://www.bbc.co.uk/programmes/p02wt5k2 (http://www.bbc.co.uk/programmes/p02wt5k2)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on August 21, 2015, 03:22:42 am
"Technology of the future" from the BBC Science Hour.
At 11:05 here
http://www.bbc.co.uk/programmes/p02wt5k2 (http://www.bbc.co.uk/programmes/p02wt5k2)

Putting existing solar panels in the most inefficient place possible is technology of the future?  :palm:
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on August 21, 2015, 04:01:17 am
Want me to ask them if they'd like to go on the Amp Hour? 
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on August 21, 2015, 04:07:35 am
Want me to ask them if they'd like to go on the Amp Hour?

Not interested in having them on.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on August 21, 2015, 04:26:16 am
Want me to ask them if they'd like to go on the Amp Hour?

Not interested in having them on.
That was a joke. I just can't believe the traction they get with the media and general public. They are literally local heroes. I was fuming the other day after getting trapped in the meeting from hell. I think they're supposed be speaking at some startup rah rah deal this weekend here.

I will acknowledge they have done one thing right: the silicon is right side up. Every other aspect of it is totally, utterly wrong.

And they are beloved for it.  :palm:
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on August 21, 2015, 04:39:22 am
That was a joke.

Oops, must retune sarcasm radar.

Quote
I just can't believe the traction they get with the media and general public. They are literally local heroes.

People want to believe.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on August 21, 2015, 07:20:24 am
That was a joke.
Oops, must retune sarcasm radar.
Quote
I just can't believe the traction they get with the media and general public. They are literally local heroes.
People want to believe.
Had as discussion with a cousin over this...
She was starting being defensive and was beginning on the "you don't like innovation and green technology" line...
So I got out my calculator (I take on holidays, I'm a nerd b#tch), and I went on the "I like green but I also like maths":
And did a quick calculation proving that covering the parking spaces of her local supermarket with well orientated solar would provide loadsa km's worth of Solaroadsways equivalent EVEN if it was the much better Dutch system.
More green tech for your green means faster reduction in emissions. SIMPLE.
No forgetting the 1000's of litres of fuel not burnt to cool down cars that have been sitting in the sun.
And then I started with the invisible infrastructure costs: ripping off existing roads, building new roads, all the cabling and then maintaining the glass surface is staggering.
"Oh, that's why we did maths in school"...

France recently passed a law that obliges new buildings in towns (not houses) to have either solar panel or planted surface (grass) on their roofs.
Right now, this is the first step and it concerns not a lot of structures, but it will get tougher over the years and all buildings (new and old) will have this obligation 10 to 15 years from now.
This IS a great ecological advance but does not garner 1% of the press that the solardeadendroad gets.
And it pisses me off.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on August 21, 2015, 10:44:01 am
I can think of one very useful application for a solar path: To provide power in scenic locations, such as parks, that may be off the grid, and to do so with minimal visual impact on the surroundings.
Why do they need power?

While it may be 4x the cost per watt-hour compared to conventional solar installations, I can't think of a less unsightly way to get local power.  I'm thinking of locations like the bottom of the Grand Canyon, or island parks.
a) Paving the grand canyon with solar panels isn't unsightly?

b) Why is putting them flat better than having half the area of panels but installing them at a 45 degree angle.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: coppice on August 21, 2015, 10:57:35 am
b) Why is putting them flat better than having half the area of panels but installing them at a 45 degree angle.
For some of us laying the panels flat is far more effective than at 45 degrees, and we don't use vast amounts of energy to avoid freezing to death in winter.  :) However, even in the tropics solar roadways are a wacky idea.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on August 21, 2015, 11:24:24 am
b) Why is putting them flat better than having half the area of panels but installing them at a 45 degree angle.
For some of us laying the panels flat is far more effective than at 45 degrees
My bad. I guess I should have been more precise. I keep forgetting we're engineers here.

The grand canyon is at 36 degrees latitude. The correct angle in the Grand Canyon would be (90-36) = 54 degrees.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Delta on August 22, 2015, 12:09:41 am

For some of us laying the panels flat is far more effective than at 45 degrees, and we don't use vast amounts of energy to avoid freezing to death in winter.  :)

You just use even more in the summer trying to keep cool! 😀

If I'm ever too hot in the "summer", I can just go outside! 😕
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on October 24, 2015, 09:57:44 pm
A viewer sent me these photos of the pathway being repaired.
The glass couldn't handle the cold temps it seems as we have seen before, so they are applying a new coating to the whole thing:
http://www.bespaarenergiescan.nl/index.php/nieuwsberichten/2246-nieuwe-coating-voor-zonnefietspad-solaroad (http://www.bespaarenergiescan.nl/index.php/nieuwsberichten/2246-nieuwe-coating-voor-zonnefietspad-solaroad)


Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: crispy_tofu on October 25, 2015, 03:03:13 am
I wonder how much that would cost...  :popcorn:
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on October 25, 2015, 07:38:56 am
Wonder just how badly the panel efficiency has degraded from new, and how much worse it is compared to a regular roof mounted panel after the same length of time. Those edges look very badly clouded, and as pretty much every engineer knows a solar panel is only as good as the weakest cell.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Jeroen3 on October 27, 2015, 06:33:07 pm
It has not even been cold yet. It says it cannot handle the transitions.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on October 29, 2015, 07:41:38 am
And then add the splitting power of water vapour...
I can see certain types of laminated glass holding up to this, but it's the kind used for bank windows: very expensive.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: NANDBlog on October 29, 2015, 09:40:03 am
It has not even been cold yet. It says it cannot handle the transitions.
They should just put electric heating into it, so it doesnt break.
Also if they would put street lights above it, it could generate power even at night.
Sorry, I've run out stupid things to say.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on October 29, 2015, 11:38:14 am
It has not even been cold yet. It says it cannot handle the transitions.
They should just put electric heating into it, so it doesn't break.
Also if they would put street lights above it, it could generate power even at night.
Sorry, I've run out stupid things to say.
And tarmac for better grip.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Delta on October 29, 2015, 12:15:00 pm
It has not even been cold yet. It says it cannot handle the transitions.
They should just put electric heating into it, so it doesn't break.
Also if they would put street lights above it, it could generate power even at night.
Sorry, I've run out stupid things to say.
And tarmac for better grip.

Now we're getting somewhere!

Put tarmac down for better grip and longevity, and overcome the problem of the tarmac blocking the sun by raising the panels a few metres from the road, maybe with some type of "pole" or suchlike...

I see a Kiskstarter coming of for this revolutionary idea!  "TarmacRoadSolarPanelsOnPolesWay"
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: coppice on October 29, 2015, 12:19:27 pm
It has not even been cold yet. It says it cannot handle the transitions.
They should just put electric heating into it, so it doesn't break.
Also if they would put street lights above it, it could generate power even at night.
Sorry, I've run out stupid things to say.
And tarmac for better grip.

Now we're getting somewhere!

Put tarmac down for better grip and longevity, and overcome the problem of the tarmac blocking the sun by raising the panels a few metres from the road, maybe with some type of "pole" or suchlike...

I see a Kiskstarter coming of for this revolutionary idea!  "TarmacRoadSolarPanelsOnPolesWay"
Then you just need to move it to South Korea and site it in the central reservation of a motorway.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Jeroen3 on November 13, 2015, 06:31:13 am
Quote
12 november 2015
Eén jaar SolaRoad Krommenie: energieopbrengst 9800 kWh
http://us7.campaign-archive1.com/?u=fc23dec47019a23d70031492e&id=4352399d96 (http://us7.campaign-archive1.com/?u=fc23dec47019a23d70031492e&id=4352399d96)

9800 kWh at a price of 3 million euro (iirc). That is 300 euro per kWh!
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: firewalker on November 13, 2015, 11:13:37 am
Have they started production?

Alexander.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Jeroen3 on November 13, 2015, 01:55:08 pm
No, the first year of tests has been completed. They think the solaroad will have "significant contribution" to the energy production.
http://www.nu.nl/wetenschap/4163420/zonnepanelenfietspad-levert-drie-huizen-stroom-in-jaar.html (http://www.nu.nl/wetenschap/4163420/zonnepanelenfietspad-levert-drie-huizen-stroom-in-jaar.html)  Translated http://bit.ly/1PFOjbX (http://bit.ly/1PFOjbX)

They are going to build more locations, and research the viability of solar bus lanes.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on November 13, 2015, 05:49:18 pm
They already had failures with just a low load presented by a bicycle, and now they want to take the same thing and both put a 10 ton point load on the cells, along with it moving across at high speed making a compression wave in the units. Add to that a really good grinding paste of sand and rubber scouring pads ( also known as tyres) to wear the glass to a matt finish in a few weeks.

You would be better off making a roofed bus lane and putting solar panels on it, at least it will be somewhat self cleaning and the efficiency will be a lot better, plus it will be a whole lot cheaper. The only time I see a need for the panel in the ground is to have one in the middle of a remote park that powers a small light where you do not want the panel to obscure the view, and need a low amount of light for night use but laying a power cable is either too expensive or involves digging up a protected environment.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: PA0PBZ on November 13, 2015, 07:13:08 pm
They already had failures with just a low load presented by a bicycle

It was temperature changes (so they say) and it was just the top layer coming off.

Quote
and now they want to take the same thing and both put a 10 ton point load on the cells

A bus with passengers weighs about 15 ton, so divide that by the number of wheels to get a correct figure.
I'm not defending them, but they still categorize it as experiments so let them play and when it doesn't work - fine.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: mullecy on December 22, 2015, 06:59:52 pm
I agree with 90% of what you said, but I think that there are mistakes in you calculations. The first one is taking 50% of one year production for that 6 months period mainly in winter. I suggest you look at results from neighbors as a reference and you'll find that 30% is a better estimate. The expected power is not 25Wh/m2 on that period but between 15 and 20. So 24.5 is significantly more. The second problem I have in your results is that it's all based on your estimation of the surface of the road. Any significant error there will change your results a lot. As a conclusion I'll say that yes, the results are actually better than expected, but that doesn't mean it's a good idea. I prefer the Korean way. But I also think that panels in the middle of a freeway is not that good, because you have to close lanes for maintenance: panels on sides would be better but would increase the width of the freeway.

...

If you sum the production of 6 months from your first neighbor http://pvoutput.org/aggregate.jsp?p=0&id=24667&sid=22510&t=m&gs=0&v=0&o=date&d=desc (http://pvoutput.org/aggregate.jsp?p=0&id=24667&sid=22510&t=m&gs=0&v=0&o=date&d=desc) , from November 2014 to April 2015 included you get 743.15kWh. If you do the sum for a full year from May 2014 to April 2015, you get 2354.88kWh. So for 6 months mainly in winter you get only 31.56% of the production of one year. So For panels in the same region in the same period you should get a similar result. So the expected production for 6 months in winter is 15.8 and not 25. For the second reference it's 32.8% giving 16.4 and for the third it's 30.08% giving 15kWh/m2... The differences from one neighbor to another one depends on the orientation of the panels. Panels "more vertical" can produce more in winter (with sun low above horizon) but will loose efficiency in summer. Horizontal panels are affected a lot in winter because sun barely illuminates them. The 15kWh/m2 is for panels at an angle (on roofs). So for horizontal panels, the reference expected production in winter is even lower than those 30%. Doing almost 25 means that the year production should be over 75kWh/m2 and may be close to 100kWh/m2

-now we have one year results: 9800kWh produced
the 3000kWh produced during 6 months of winter time was then only 30.6%, far from the 50% value Dave based his calculations on...

-using the 122.5m2 estimated surface we get 80kWh/m2 much more than the 50kWh/m2 expected and even higher than best case 70kWh/m2
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on December 22, 2015, 08:06:15 pm
I agree with 90% of what you said, but I think that there are mistakes in you calculations. The first one is taking 50% of one year production for that 6 months period mainly in winter. I suggest you look at results from neighbors as a reference and you'll find that 30% is a better estimate. The expected power is not 25Wh/m2 on that period but between 15 and 20. So 24.5 is significantly more. The second problem I have in your results is that it's all based on your estimation of the surface of the road. Any significant error there will change your results a lot. As a conclusion I'll say that yes, the results are actually better than expected, but that doesn't mean it's a good idea. I prefer the Korean way. But I also think that panels in the middle of a freeway is not that good, because you have to close lanes for maintenance: panels on sides would be better but would increase the width of the freeway.

...

If you sum the production of 6 months from your first neighbor http://pvoutput.org/aggregate.jsp?p=0&id=24667&sid=22510&t=m&gs=0&v=0&o=date&d=desc (http://pvoutput.org/aggregate.jsp?p=0&id=24667&sid=22510&t=m&gs=0&v=0&o=date&d=desc) , from November 2014 to April 2015 included you get 743.15kWh. If you do the sum for a full year from May 2014 to April 2015, you get 2354.88kWh. So for 6 months mainly in winter you get only 31.56% of the production of one year. So For panels in the same region in the same period you should get a similar result. So the expected production for 6 months in winter is 15.8 and not 25. For the second reference it's 32.8% giving 16.4 and for the third it's 30.08% giving 15kWh/m2... The differences from one neighbor to another one depends on the orientation of the panels. Panels "more vertical" can produce more in winter (with sun low above horizon) but will loose efficiency in summer. Horizontal panels are affected a lot in winter because sun barely illuminates them. The 15kWh/m2 is for panels at an angle (on roofs). So for horizontal panels, the reference expected production in winter is even lower than those 30%. Doing almost 25 means that the year production should be over 75kWh/m2 and may be close to 100kWh/m2

-now we have one year results: 9800kWh produced
the 3000kWh produced during 6 months of winter time was then only 30.6%, far from the 50% value Dave based his calculations on...

-using the 122.5m2 estimated surface we get 80kWh/m2 much more than the 50kWh/m2 expected and even higher than best case 70kWh/m2

So you spent 3 million Euro to generate 2000 Euro of power in a year.  You might want to consider a career outside of the power industry.  Any competent developer could have installed a 1MW array.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: PA0PBZ on December 22, 2015, 08:30:00 pm
So you spent 3 million Euro to generate 2000 Euro of power in a year.  You might want to consider a career outside of the power industry.  Any competent developer could have installed a 1MW array.

The 3 million was spend on research and development, not just to build the thing.
They expect a break-even for this over 15 years.

Again, not defending them at all but get your facts right.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on December 22, 2015, 09:04:45 pm
So you spent 3 million Euro to generate 2000 Euro of power in a year.  You might want to consider a career outside of the power industry.  Any competent developer could have installed a 1MW array.

The 3 million was spend on research and development, not just to build the thing.
They expect a break-even for this over 15 years.

Again, not defending them at all but get your facts right.

That "R&D" never should have been embarked upon since a few, simple calculations performed on the back of a coaster with a dull golf pencil would have shown it to be moronic.  I feel completely justified in including it in the total, since non-recurrent engineering is always part of the cost of a power project. 

The fact remains that the money could and would have purchased a competent solar project that would produce useful power today *without* any "R&D."
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on December 22, 2015, 09:30:31 pm
So you spent 3 million Euro to generate 2000 Euro of power in a year.  You might want to consider a career outside of the power industry.  Any competent developer could have installed a 1MW array.

The 3 million was spend on research and development, not just to build the thing.
They expect a break-even for this over 15 years.

Again, not defending them at all but get your facts right.

That "R&D" never should have been embarked upon since a few, simple calculations performed on the back of a coaster with a dull golf pencil would have shown it to be moronic.  I feel completely justified in including it in the total, since non-recurrent engineering is always part of the cost of a power project. 

The fact remains that the money could and would have purchased a competent solar project that would produce useful power today *without* any "R&D."
How much was spent designing the 1st Opamp? How much cost a tube amp back then? Same thing.

Not defending solar roadways (I think it's crap), but sometimes doing purposefully things "badly" is useful in learning unforeseen things (laminating glass pathways could have other better uses) and/or to shut up idiots who can't hold a calculator the right way up ("them" not you).
In any case, 3millions Euros is a drop in the Netherlands green energy budget.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on December 22, 2015, 10:53:37 pm
A bus with passengers weighs about 15 ton, so divide that by the number of wheels to get a correct figure.

A lot more than that if the bus slams on the breaks.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on December 22, 2015, 10:58:45 pm
Do they have any projected estimates on the cost of the path? (minus R&D)
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on December 23, 2015, 01:11:51 am
So you spent 3 million Euro to generate 2000 Euro of power in a year.  You might want to consider a career outside of the power industry.  Any competent developer could have installed a 1MW array.

The 3 million was spend on research and development, not just to build the thing.
They expect a break-even for this over 15 years.

Again, not defending them at all but get your facts right.

That "R&D" never should have been embarked upon since a few, simple calculations performed on the back of a coaster with a dull golf pencil would have shown it to be moronic.  I feel completely justified in including it in the total, since non-recurrent engineering is always part of the cost of a power project. 

The fact remains that the money could and would have purchased a competent solar project that would produce useful power today *without* any "R&D."
How much was spent designing the 1st Opamp? How much cost a tube amp back then? Same thing.

No. It's huge difference. It's fundamental physics as opposed to the application of an utterly commoditized technology. One begets the other, but they are worlds apart.

As for $3M being chump change, I'll be sure to tell my clients that. That's lawyers and guns money even on a $200M power plant. You don't see private developers building solar roadways with their own money for a good reason.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: EEVblog on December 23, 2015, 02:25:50 am
No. It's huge difference. It's fundamental physics as opposed to the application of an utterly commoditized technology. One begets the other, but they are worlds apart.

And that's always been the crux of this whole concept (Solar Freak'n Roadways or SolaRoad).
They are not doing research on making more efficient solar panels, or finding more efficient ways to implement it. They are instead researching ways to take the worst possible way to implement an existing technology to somehow make it viable. It's a fundamentally dumb idea. Apart from possibly having some appeal in some niche applications of course.
But to think that this idea is going to be viable and a benefit to society on a global scale is demonstrably laughable.


Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on December 23, 2015, 07:56:03 am
A bus with passengers weighs about 15 ton, so divide that by the number of wheels to get a correct figure.

A lot more than that if the bus slams on the breaks.

Bus lane will also have trucks on it, like garbage trucks, trucks turning corners and such. If you do not design it to handle a maximum axle load and a safety factor you are in for a lot of early damage. Here max all up combination mass is 56 tons, with up to 12 tons per axle. Max recorded overload was a truck that was 130 tons over, with 2 containers that were picked up from a ship with a container lifter, and moved with a straddle carrier onto the truck. Container declared mass was 30 tons each.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on December 23, 2015, 08:01:39 am
No. It's huge difference. It's fundamental physics as opposed to the application of an utterly commoditized technology. One begets the other, but they are worlds apart.

And that's always been the crux of this whole concept (Solar Freak'n Roadways or SolaRoad).
They are not doing research on making more efficient solar panels, or finding more efficient ways to implement it. They are instead researching ways to take the worst possible way to implement an existing technology to somehow make it viable. It's a fundamentally dumb idea. Apart from possibly having some appeal in some niche applications of course.
But to think that this idea is going to be viable and a benefit to society on a global scale is demonstrably laughable.
And fully agree with you.
But you could assemble lego bricks by the age of 15, not so much the people who are the audience for this.
Doing 1+1=2 is not going to sway them if they are convinced because their tarot, god or a lettuce told them it's 3.
Telling them that a mud cake is not going to taste of chocolate is insufficient, a mud cake must be made and shoved down their throats.
But this must be well documented, so when the next idiot comes along saying that the Great Spaghetti monster told him that mud cake tastes of chocolate, another mud cake need not be made...
And this really happens.
During the early days of radar, a team in  England had to make a "death ray version"... This was because senior Whitehall members could not get their head around the fact that a signal diminishes in strength relative to distance... A pulse that might cook a chicken 3 feet away is not going to broil German pilots 20 miles away.  Wasting time and money at a crucial moment proving very basic and understood physics. But it had to be done to get these idiots back to their dusty offices and out off the way.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: mikerj on December 23, 2015, 11:36:44 am
During the early days of radar, a team in  England had to make a "death ray version"... This was because senior Whitehall members could not get their head around the fact that a signal diminishes in strength relative to distance... A pulse that might cook a chicken 3 feet away is not going to broil German pilots 20 miles away.  Wasting time and money at a crucial moment proving very basic and understood physics. But it had to be done to get these idiots back to their dusty offices and out off the way.

You have this backwards.  The idea of the "death ray" was born of desperation, but was discounted by solid engineering.  A man called Watson-Watt and his assistant calculated the power requirements and found them to be far outside anything the current technology could offer.  However, the concept of using high power directed RF energy lead to the invention of radar.

If Solar Roadways had followed a similar path then the idea would have been discounted, and the useless money-sinking demonstrator would not have been built.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on December 23, 2015, 12:06:00 pm
Bus lane will also have trucks on it, like garbage trucks, trucks turning corners and such. If you do not design it to handle a maximum axle load and a safety factor you are in for a lot of early damage.

And don't forget all the little stones that are under those tires.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: gildasd on December 23, 2015, 02:33:04 pm
During the early days of radar, a team in  England had to make a "death ray version"... This was because senior Whitehall members could not get their head around the fact that a signal diminishes in strength relative to distance... A pulse that might cook a chicken 3 feet away is not going to broil German pilots 20 miles away.  Wasting time and money at a crucial moment proving very basic and understood physics. But it had to be done to get these idiots back to their dusty offices and out off the way.

You have this backwards.  The idea of the "death ray" was born of desperation, but was discounted by solid engineering.  A man called Watson-Watt and his assistant calculated the power requirements and found them to be far outside anything the current technology could offer.  However, the concept of using high power directed RF energy lead to the invention of radar.

If Solar Roadways had followed a similar path then the idea would have been discounted, and the useless money-sinking demonstrator would not have been bui

From what I remember reading, some mathematically illiterate Whitehall monuments clung on to the "death ray" all the way into 1941 despite the calculations showing it's impossibility years before, leading to a serious time and money loss. Ending up do an experiment with chickens and/or tea in 1941, before the whole idea was quietly shelved - but I am going from memory and could be quite wrong.
In any case, you have given me the desire to dig up old books and refresh my knowledge, thanks!

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on December 25, 2015, 06:52:30 am
Anybody want to consider the next roadway build as a fine place to leave Mojo? Preferably after some nice new boots are installed.
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: RickBrant on February 02, 2016, 05:34:11 pm
No. It's huge difference. It's fundamental physics as opposed to the application of an utterly commoditized technology. One begets the other, but they are worlds apart.

And that's always been the crux of this whole concept (Solar Freak'n Roadways or SolaRoad).
They are not doing research on making more efficient solar panels, or finding more efficient ways to implement it. They are instead researching ways to take the worst possible way to implement an existing technology to somehow make it viable. It's a fundamentally dumb idea. Apart from possibly having some appeal in some niche applications of course.
But to think that this idea is going to be viable and a benefit to society on a global scale is demonstrably laughable.

Did anybody divide the cost to build that silly bikepath by the average long-term power output?

It cost a staggering $5000 per watt!

Residential solar rooftop installs in the US are running around $5 per watt! And I imagine the installation costs would be far less if you put the panels on the ground (properly angled, of course). Like we see in the desert in western Arizona.

So to just break even with rooftop they're going to need a factor of 1000 improvement.

Now, sure, this was a first-time effort. The way of using solar panels under a walkable surface had to be developed, etc., etc. Once the methods were established we could expect costs to fall.

But... by a factor of 1000?

Note: developments in better solar panels will not help with that, because any such development can be applied equally well to rooftop solar. Thus solar panel improvements will not contribute one iota to the needed factor of 1000. They'll have to make it up elsewhere. Good luck with that.


Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: Fungus on February 02, 2016, 05:59:38 pm
Did anybody divide the cost to build that silly bikepath by the average long-term power output?

Price doesn't matter when you're saving the environment.

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: JohnMoosenl on February 22, 2016, 06:10:19 am
Did anybody divide the cost to build that silly bikepath by the average long-term power output?

Price doesn't matter when you're saving the environment.
But eventually you run out of other people's money..
Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: SeanB on April 17, 2017, 01:54:46 pm
Well, the results are out as to the ROI on the solar roadway test article. Generated pretty poor power, and absolutely no mention of the power consumed in that period in the heaters, LED "welcome to blinky" displays and in the cabinet as inefficiency, but hey, it did make 10c per day, on a good day.

Thunderfoot follows....

https://www.youtube.com/watch?v=Yg64h2jrDVw (https://www.youtube.com/watch?v=Yg64h2jrDVw)

Title: Re: EEVblog #743 – Solar Roadways Test Results
Post by: LabSpokane on April 17, 2017, 02:12:21 pm
Well, the results are out as to the ROI on the solar roadway test article. Generated pretty poor power, and absolutely no mention of the power consumed in that period in the heaters, LED "welcome to blinky" displays and in the cabinet as inefficiency, but hey, it did make 10c per day, on a good day.

Thunderfoot follows....


And again, the critics use math and science as bad as what was used to justify the solar roadway.  This guy is just wrong.  1kW of solar panels does not generate 1kW of power from sunup to sundown.  :palm:

This is a 30 year average of what can be expected in Spokane, WA (nearest PVWatt datapoint) for yesterday, 16 April.  Please note the graph of output is not a step function. 

The total expected output on this (sum under the curve with 1hr binning) is about 4.3kW-h for a 1320W system at 0 deg tilt.  The best I've seen out of SolarRoadways thus far for April is 1.1kW-h.  So, with more data, we're seeing SR generating about 25% the power that it should be if properly sited and designed. 

(https://www.eevblog.com/forum/blog/eevblog-743-solar-roadways-test-results/?action=dlattach;attach=308931;image)
(https://www.eevblog.com/forum/blog/eevblog-743-solar-roadways-test-results/?action=dlattach;attach=308933;image)