
Output of Dutch solar bike lane exceeds expectations - Rafert
https://translate.google.com/translate?sl=nl&tl=en&js=y&prev=_t&hl=nl&ie=UTF-8&u=http%3A%2F%2Ftweakers.net%2Fnieuws%2F102994%2Fopbrengst-fietspad-met-geintegreerde-zonnepanelen-is-boven-verwachting.html&edit-text=
======
meric
Roads are quite a good place to place solar panels, logistically speaking. Yes
they are 30% less efficient, but they are also closer to where the electricity
will be used, and the marginal opportunity cost of real estate is zero since
road use is retained. You don't need new land and you don't need to worry
about transporting power at great distances. I'm glad such experiments are
being conducted to see how well this idea performs in practice. It's good they
started with bike lane as opposed to truck roads. It will give them
opportunity to iterate on the panels resiliency.

~~~
guiomie
Not sure why you are being downvoted, but I thing your comment makes a lot of
sense, and I'd like to know why some think otherwise.

~~~
hoopd
Logistically speaking, there's a nightmarish level of complexity introduced
here. Put a country's food distribution network on top of its energy
production system? Put solar cells where you know they'll be constantly driven
over by heavy machinery? Replace some of the most durable materials known to
man (asphalt and concrete) with glass encased electronics?

These things aren't impossible, but it's such an uphill battle that I wouldn't
hold my breath. ([http://jalopnik.com/why-the-solar-roadway-is-a-terrible-
idea...](http://jalopnik.com/why-the-solar-roadway-is-a-terrible-
idea-1582519375))

~~~
Retric
Thick pices of tempered glass are vary durable and could easily outlast
asphalt as a road surface. Right now the decreased efficiency makes this a non
starter, but long term if solar keeps getting cheaper it may become a
reasonable supplement to the power grid.

PS: Bullet resistant glass is surprisingly clear dispite how thick it is.

~~~
ljf
I wonder what the stopping distance is on this glass?

~~~
dogma1138
Not as big as wet glass or icy glass ;)

------
dorfsmay
I'd love to see some financial analysis:

1) cost of producing the same amount of electricity with Netherlands' most
common electricity production

2) cost of building this vs. a normal bike path, and time for recovering the
cost considering #1

3) expected life of this system + anual maintenance cost

4) cost of a typical roof installation for the same surface

~~~
quchen
5) Cost of a normal bike path with ordinary solar cells of equal area next to
it

~~~
ghshephard
5.1 Cost of a normal bike path with ordinary solar cells on _top_ of it
(providing shade, and shelter from the rain, with presumably greater
efficiency)

~~~
mod
This is actually what I envisioned before I looked up some pictures (if there
were any in the article, they didn't load for me).

It seems more practical, in particular for a bike path.

~~~
greglindahl
That's already well-studied, for parking lots with shade structures.

I'm astonished how many people are weighing in to trash a small project
researching something new that might be interesting!

~~~
ghshephard
I'm definitely not trashing it - I'm enthusiastically interested in whether
it's viable. What I'd love to know is what the expected cost structure, at
scale might be, in comparison to other options.

------
hoopd
Really? On their website[0] they claim their _glass surface_ doesn't require
snow removal because the heating elements melt it and as such asphalt roads
have a cost of snow removal that apparently comes for free with these.

However, it takes more energy to melt snow than to push it to the side[1]
which they simply ignore and that makes me question what other things they're
leaving out in order to tell a good story. I'd really like to see the numbers
crunched for how many snowy days a year will cause the system to consume as
much energy as it produces.

[0] -
[http://solarroadways.com/snow.shtml](http://solarroadways.com/snow.shtml) [1]
- [https://what-if.xkcd.com/130/](https://what-if.xkcd.com/130/)

~~~
woah
It takes moe energy to melt snow than push it to the side? This is
northwestern Europe, where the snow never gets more than a few centimeters
deep, and the temperatures never go more than a few degrees below freezing. I
could definitely see heating a surface by a few degrees being cheaper than
bringing a plow or other snow clearing machinery out to some path.

Now, northern Canada would probably be a different story.

~~~
onnoonno
The enthalpy of fusion for water is 335 J/g. The specific heat capacity of ice
at -10C is 2.1 J/(gK). So the major part in melting the water isn't heating it
until it melts - it is the melting itself that is expensive.

That said, I do see some value in solar ways in the space savings.

~~~
stcredzero
Why not awnings over the bike path? This can be done in ways that look awesome
and do not ruin the scenery and the view from the bike path. Thin film
collectors in the form of tarps suspended from poles would make the
installation cost commensurate with installing light poles. You'd need
significant R&D in the aerodynamics, etc. However, you already need
significant R&D for collector roadways, and you're starting out with an
inherently disadvantaged design.

------
Someone
The FAQ of the project at
[http://www.solaroad.nl/en/faq/](http://www.solaroad.nl/en/faq/) is worth
reading. Among others, it explains that the €3.5M spent wasn't only used to
produce this stretch of road (unfortunately without going into detail), and
that covering _all_ rooftops in the Netherlands would only cover 25% of Dutch
_electricity_ demand.

Given European clean energy goals, more square meters are needed. Those are
hard to come by in a densily populated country such as the Netherlands.

Is this a sure win? No, but if it works, it can be a useful part of the energy
mix. Also, if it works, I guess scaling it up will not meet much nimby
resistance, unlike he alternatives of huge wind parks or sacrificing land or
water area for solar arrays.

------
invisible
Sounds like the first comment hit the nail on the head: there being 25% more
sunlight hours than expected.

------
stephengillie
Interesting points:

1\. > _That is more than the upper limit calculated on the basis of laboratory
tests._

Does this mean the panels generated more than they were tested to generate?

2\. Part of the purpose of the project was to beta test the suitability of
their glass surface treatment as a biking/walking surface. (I'm imagining it's
textured like a truck bed liner, but transparent.) They did have an incident
early on with a bicyclist slipping, related to a stick-on surface, so they
switched to a spray-on surface.

3\. Commenters slinging arrows at a Conservative strawman for the high price
and comparatively low (factor of 500) energy output vs government building
rooftops.

~~~
Rafert
1\. No, it means that the panels generated more than the predicted upper
bound. As a commenter on the source article mentioned, this year's April was
one of the most sunny in recorded Dutch weather history, which might have
contributed to this fact.

------
jimrandomh
Numbers from the article:

3000 kWh in six months = 684W average

70 kWh per m^2 per year = 8W per m^2

As a comparison point,
[https://en.wikipedia.org/wiki/Photovoltaic_system#Solar_arra...](https://en.wikipedia.org/wiki/Photovoltaic_system#Solar_array)
gives a typical output for a square-meter panel as 0.75kWh per day, or 31W.

~~~
jsnell
That's the wrong 6 months though, since it's including the whole winter and
none of the summer. Looking at the graph, April accounted for as much power
production as the other 5 months combined.

------
suls
Could this be the missing link to make electric cars winning the battle? No
need for plugs at gas stations, inductive charging [1] while driving on the
road will do it.

Am I being too futuristic?

[1]
[http://en.wikipedia.org/wiki/Inductive_charging#Electric_veh...](http://en.wikipedia.org/wiki/Inductive_charging#Electric_vehicles)

~~~
dredmorbius
No.

And no. The fault isn't Futurism but fantasy.

------
gus_massa
> _The cycle path was opened in November as a pilot project for three years
> and was followed with great interest, also by foreign media._

I'm not following this new very closely. "Open" means that they allow cyclist,
pedestrian (and dogs) to use a small 70m pilot segment, or that they have a
70m segment in the middle of nowhere?

~~~
panarky
Here's a photo. It's a bike path between two towns, and about 2000 cyclists
per day ride on it.

[http://www.theguardian.com/environment/2014/nov/05/worlds-
fi...](http://www.theguardian.com/environment/2014/nov/05/worlds-first-solar-
cycle-lane-opening-in-the-netherlands)

~~~
ChrisGranger
It cost three million euros but can only power three houses? A _million euros_
to use solar to power a house? Am I missing something?

~~~
fche
Government economics, working as designed.

~~~
learnstats2
>Government economics, working as designed.

You've been downvoted perhaps because it's not clear if you're being
sarcastic, but I agree earnestly.

The primary purpose of government is to organise things that benefit people:
and they only need to do this when business can't or won't. Governments should
act as a balance to the negative aspects of capitalism.

As such, I genuinely believe that governments should be "uneconomic".

------
lotsofmangos
Well, it makes slightly more sense than the solar roads for normal cars and
trucks, if only because it doesn't have to be quite as tough, but I do suspect
that it would be cheaper to install, easier to maintain and far more efficient
in terms of power generation, to put a normal cycle path down and put a roof
of solar above it.

~~~
reirob
Yes, but it wouldn't be as pleasant to ride on the road. Riding a bike with a
roof over your head? I don't know, but I appreciate seeing the sky and the
horizon when riding a bike.

~~~
lotsofmangos
It wouldn't be a roof exactly. Because you can angle the panels and have much
better transmission of light to the panel from not having to have a bike-proof
coating, you wouldn't be completely covering the path and you would get the
same amount of power from a strip that is thinner than the path, angled and
fairly high up, this would cost far less money as it is available off the
shelf, so you have more cash to spend on making more of it. Also, if you
integrate it with lamp posts for your support pillars, you are not increasing
the amount of street clutter either.

------
toast0
Are Dutch bike lanes like US bike lanes? Adjacent to motor vehicle lanes, with
no grade separation, and an expectation that motor vehicles will use the lane
whenever it is convenient, regardless of right of way? If so, this is really
solar panels for the right shoulder, and I would really expect a big truck to
break them

~~~
PhasmaFelis
The title seems to be inaccurate. The test area is a dedicated bike path, not
attached to a standard road.

------
ukandy
Why anyone would pursue such a suboptimal installations is beyond me.
Researchers finding ways to waste grant money I guess..

~~~
Someone
The company leading the project claims commercialization is five years away.
They likely are optimistic or biased, but I am not sure they are outright
lying.

Prices of solar cells drop fast. Extrapolate a few years, and costs of solar
installations will be dominated not by what solar cells cost, but by what it
costs to install them.

In this case, something must be installed anyways to build the cycle path. It
might well be that installing a (cycle path, solar cells) combination will
only be marginally more expensive than installing a traditional cycle path.

Will we get there? If solar cells and the electronics needed to wire than
together (which, in this case, are more complex because the road may see
highly variable shading patterns) get dirt cheap, we might.

~~~
mason240
Do you really believe that it is more efficient to build a bike lane paved
with solar panels, rather than a bike lane paved with asphalt and separate,
dedicated solar facilitates?

EDIT: Looking at the pictures others have posted you still have to use asphalt
(or more likely concrete because you need better stability, which is even more
expensive) underneath, so there really is nothing saved by doing this. What a
waste of money.

~~~
drabiega
How is the presence of asphalt underneath an issue? The deciding factor will
be whether the marginal cost of a solar path over an asphalt path will be
greater or less than building an equivalent solar facility. That seems like it
could go either way.

~~~
IkmoIkmo
Very good point. Plus even if the marginal cost is lower than a dedicated
solar facility, we don't necessarily have that luxury. We do if we want just
5% sustainable energy, not a problem. But if we want 99% sustainable energy,
surface area is a very tricky challenge [0] and so it'd be a matter of the one
_and_ the other, instead of the one _or_ the other.

[0]
[https://www.youtube.com/watch?v=GFosQtEqzSE](https://www.youtube.com/watch?v=GFosQtEqzSE)

------
Giorgi
Why is it bike lane though? any practical considerations?

~~~
Maarten88
In the video they explain they use a bike lane to learn before going to real
roads. Bikes are much lighter than cars and trucks, and they want to learn
what materials work best.

------
jkot
What were the expectations?

~~~
Rafert
According to [http://www.solaroad.nl/wp-content/uploads/2013/06/Artikel-
So...](http://www.solaroad.nl/wp-content/uploads/2013/06/Artikel-SolaRoad-
BU2013.pdf) it was 50 kWh per square meter.

~~~
fche
(over what unit time)?

~~~
icebraining
Per year.

------
rebootthesystem
Sorry, this is beyond silly. Do they actually have any scientists with some
command of mathematics working on this project?

Other than to screw ignorant government morons out of lots of money I could
not imagine any reputable scientist or engineer not falling to the floor
laughing uncontrollably when presented with the idea of putting solar panel on
a sidewalk/bike path.

The whole thing is so utterly ridiculous that the only possible explanation is
someone is making millions with this project.

~~~
rebootthesystem
The dynamics of down-voting on HN can be interesting. I have this --possibly
flawed-- mental image of emotional impulse voting devoid of any effort to
analyze what is being said.

For the benefit of those who didn't take the time to think before down-voting
my prior comment I'll try to spell it out here.

A few facts:

\- Good commercial cells deliver an efficiency in the 14% to 19% range.

\- This efficiency assumes the cells are aimed at the sun

\- Optimal winter angle for the Netherlands is approximately 76 degrees from
horizontal

\- Peak efficiency also assumes the cells are clean and have nothing
obstructing or altering light from reaching it's surface at the optimal angle

\- In all cases you can Google my claims and verify their veracity

Option #1:

\- Cover the solar panels with glass \- Scuff-up the surface so people and
bikes don't slip and slide all over the place \- As an alternative, apply a
film to achieve the same effect \- Mount them flat on the ground \- Place
trees around it \- Have people, bikes and dogs walk on it

Analysis:

\- The cost of encasing panels in concrete and glass modules and installing
them is monumental

\- The optimal angle for Amsterdam is approximately 76 degrees. Panels mounted
flat simply throw away a significant amount of available energy.

\- Solar cells laid flat will produce between 20% and 30% less when compared
to optimally aimed cells.

\- Glass will create problems based on how light enters. You have reflection,
diffraction and scattering as possibilities. A percentage of the energy will
never reach the cells.

\- A non-slip surface will scatter and absorb a significant amount of energy.
Based on the images I've seen of these road modules I am going to guestimate
that at best 70% of the light entering the road reaches the cells. I base this
on years of working with a wide range of optical diffusers.

\- Dirt and particles on the cells can have huge efficiency effects. From
light scattering to simply blocking and absorption. I'll go ahead and guess
that you can't keep a roadway clean 100% of the time, therefore, you probably
pay a, say, 20% penalty on average for having dirt, leaves and dog shit on the
road. This is entirely a seat-of-the-pants number. It could be 10% or 50%. It
isn't going to be zero.

\- Power generation is now utilization dependent. With more people on the road
more light is blocked and less power is generated. I won't put a number to
this. I will rather make a statement: If nobody uses the road, what's the
point of building one in the first place or building one that is so much more
expensive than simply pouring plain concrete?

\- Depending on angle, trees, buildings and even tall vehicles on the road
will cast shadows on the panels.

A very rough calculation then says that, at best, our solar roadway will
operate at 40% of peak efficiency. If we factor in the constant need for
cleaning this number could very well go down significantly. For example, do we
have a crew of a few people using gas powered leaf blowers cleaning the
roadway a few times a day?

Option #2: Build a light steel structure atop a conventional bike path. Angle
the panels for optimal efficiency at that latitude. You might splurge and add
active tracking.

Analysis:

\- The cost of installation is significantly lower

\- By mounting the panels at the optimal collection angle we ensure converting
power as near to the efficiency peak for the panel in question

\- Angled mounting also aids in reducing surface particulate contamination and
makes cleaning potentially as simple as an automated water sprinkler system

\- The entire system is far less costly and efficient

\- The bike path gets "free" shade as a side effect

So, yeah, the entire idea is absolutely ridiculous if anyone bothers to do a
little math. Someone has got to be lining their pockets or whoever is leading
this project is simply in denial.

Go ahead and downvote, but, if you do, please show your calculations and how
you arrived at the idea that this concept actually makes sense to deploy at
scale. I'll bet you can't.

