EEVblog #743 – Solar Roadways Test Results

[BobC]

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.)

[miguelvp]

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:

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.

[EEVblog]

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 

[coppice]

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.

[mullecy]

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 , 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

[max_torque]

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! 

[Jay_Diddy_B]

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'   

Regards,

Jay_Diddy_B

[mullecy]

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! 

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...   

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.

[EEVblog]

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...   

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.

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.

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.

[EEVblog]

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.

[Fungus]

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".

[EEVblog]

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?

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

Correct that to $56 sqm.
Still pretty dismal.

[EEVblog]

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?

[Fungus]

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 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.

[EEVblog]

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.

[Fungus]

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.

[EEVblog]

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.

[ali_asadzadeh]

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!

[Fungus]

[mullecy]

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 ?

[rsjsouza]

BTW, I saw the Solar Roadways wiki page has links to Dave's videos and added this last one.

[m100]

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   

[Jeroen3]

Mayve we should be paving dikes with solar panels to become profitable. 

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.

[LabSpokane]

And the prize for best lede on Solar Roadways goes to:

http://breakingenergy.com/2015/05/13/solaroad-performs-better-than-expected-remains-pointless/

[Fsck]

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.