Yet Another Cycling Forum

General Category => On The Road => Topic started by: quixoticgeek on 27 July, 2021, 09:24:38 pm

Title: The road to solar...
Post by: quixoticgeek on 27 July, 2021, 09:24:38 pm

A week or so ago, a "solar cycle path" was opened near Maartensdijk in the province of Utrecht, Netherlands.

The project costs €3.3m, and generates enough power for 3 homes.

When I saw the press release, I wrote a long twitter thread about how it's basically a shit idea, purely from a amount of power from the angle of the cells, and the cost.

You can read that thread here:

https://twitter.com/quixoticgeek/status/1416178859544829957

Since then I found myself cycling across it at the weekend. I hadn't realised it was on my route until I approached it.

I took a video of riding along it, which you can find here:

https://www.youtube.com/watch?v=5tIyv8S74fM

I also took some photos.

(https://pbs.twimg.com/media/E7U-G7sXIAISCex?format=jpg&name=large)

It looks on first approach like the standard concrete panel construction, but slightly the wrong colour, then as you get closer you realise it's translucent glass. The surface has an interesting texture. It reminded me of woodchip wallpaper, and chipseal.

(https://pbs.twimg.com/media/E7U_FnJXMAUmhC9?format=jpg&name=large)

My biggest thought when I saw the announcement was it would be slippery. But I'm pleased to see it shouldn't be too bad. Heavy rain and long term wear may effect this.

(https://pbs.twimg.com/media/E7U_fSEXEAAENoA?format=jpg&name=large)

Up close you can see the texture of the surface.

(https://pbs.twimg.com/media/E7U_-hLXsAEehTS?format=jpg&name=large)

Ultimately this is a €3.3m vanity project, and a gimmick. Given you could generate the same power from the roof of 3 homes, and the cost per house would be no greater than €25k per house. I don't understand why anyone would want to do this. It doesn't make financial sense. It doesn't make energy efficiency sense. If we had completely exhausted every other suitable rooftop, then it may be worth considering other areas like this, but given 99.9% of the roofs I can see from my window are devoid of solar, we're a long way from that point. That €3.3m could get a lot of roof top solar. And if we really did want to get solar from this cycle path, we'd get a higher yield by building a cover over the top covered in solar panels, which would also protect us from the rain...

J
Title: Re: The road to solar...
Post by: Kim on 27 July, 2021, 09:37:12 pm
Solar frikkin' roadways!

I think it's daft[1] for all the reasons you do, but it was probably worth someone somewhere building one to prove the point.


[1] I concede there may be some edge case where a large expanse of lightly-used tarmac that can't be covered (racing track or an emergency runway or something maybe?) might be usefully employed to generate electricity, but it's never going to make sense for roads or car parks.
Title: Re: The road to solar...
Post by: Cudzoziemiec on 27 July, 2021, 10:12:48 pm
I'd actually heard of this idea though I can't remember in what context, so it's interesting that you've encountered one. I'm glad it wasn't too bad to ride on, it looks as if the joins between panels might have got a bit annoying in a thunk-thunk way.

Looks like a pretty silly way to use PV panels. I suppose if you have some spare and you're building a road anyway, it isn't a total waste...

Plus it gives me an excuse to play with teh Jarvis.

It reminded me of woodchip wallpaper, and chipseal.
Your road was very poor,
With woodchip on the floor.
Title: Re: The road to solar...
Post by: LittleWheelsandBig on 27 July, 2021, 10:13:42 pm
The proof of concept of almost everything is overly expensive and not particularly efficient.

A solar panel frame over the top of a normal cycleway would be pretty expensive too. Uplift from wind is a major issue and would need decent foundations. The frame would need to be tall enough for fairly large maintenance vehicles to fit underneath and the supports be able to withstand a low speed impact. At least it is easier to clean or maintain solar cells at ground level.

Don’t get me wrong, this is a silly idea but the issues need to be demonstrated. This will do so.
Title: Re: The road to solar...
Post by: nuttycyclist on 27 July, 2021, 10:20:27 pm
"The project costs €3.3m, and generates enough power for 3 homes. "    WTF?    Is that really a useful spend of money?



It'd also be nice if any of the photos you post actually display instead of just being blank boxes.
Title: Re: The road to solar...
Post by: grams on 27 July, 2021, 10:20:47 pm
I suppose if you have some spare and you're building a road anyway, it isn't a total waste...

But the foundation must be much more flat and solid and the top surface needs to be made out of glass, which we don't normally use for roads for countless obvious reasons.
Title: Re: The road to solar...
Post by: LittleWheelsandBig on 27 July, 2021, 10:24:58 pm
I suppose if you have some spare and you're building a road anyway, it isn't a total waste...

But the foundation must be much more flat and solid and the top surface needs to be made out of glass, which we don't normally use for roads for countless obvious reasons.

What makes you think that there is any difference in the foundation needed?
Title: Re: The road to solar...
Post by: Kim on 27 July, 2021, 10:26:33 pm
What makes you think that there is any difference in the foundation needed?

Experience of BRITISH cyclepaths? :)
Title: Re: The road to solar...
Post by: LittleWheelsandBig on 27 July, 2021, 10:27:56 pm
Dutch cyclepaths are built to a decent standard (at a commensurate cost). Guess where this one is.
Title: Re: The road to solar...
Post by: quixoticgeek on 27 July, 2021, 10:30:20 pm
"The project costs €3.3m, and generates enough power for 3 homes. "    WTF?    Is that really a useful spend of money?



It'd also be nice if any of the photos you post actually display instead of just being blank boxes.

they are hosted via twitter, you can find them all via this thread on twitter:

https://twitter.com/quixoticgeek/status/1420109549093232641

J
Title: Re: The road to solar...
Post by: JonBuoy on 27 July, 2021, 10:34:22 pm
https://www.dutchnews.nl/news/2021/07/worlds-longest-solar-panel-bike-bath-opens-in-utrecht/ states: 'The cost of the project is put at €1.3m...' and reckons that it has '...the ability to create enough electricity to power 40 homes.'
Title: Re: The road to solar...
Post by: grams on 27 July, 2021, 10:38:39 pm
What makes you think that there is any difference in the foundation needed?

It looks to me like that road has to made to very precise dimensions to make the glass panels fit on the top. Even Dutch cycle paths are fuzzy things with complex compound curves and doubtless shift over time.
Title: Re: The road to solar...
Post by: LittleWheelsandBig on 27 July, 2021, 10:46:11 pm
The solar panels are installed on straight sections of the path and inset into/ surrounded by a flexible or rigid pavement material that is probably laid afterwards. They are not fitted to complex geometry sections with reverse curves. This isn’t rocket science.

https://inhabitat.com/solaroad-the-netherlands-unveils-worlds-first-solar-cell-paved-bike-path/ shows interlocking reinforced concrete panels that would be fairly resistant to local subsidence messing up the alignment.
Title: Re: The road to solar...
Post by: Kim on 27 July, 2021, 10:48:23 pm
Surely it's not much different from laying paving slabs?  Okay, people manage to fuck that up on a depressingly regular basis, but that doesn't mean they don't work.
Title: Re: The road to solar...
Post by: quixoticgeek on 27 July, 2021, 10:49:23 pm
https://www.dutchnews.nl/news/2021/07/worlds-longest-solar-panel-bike-bath-opens-in-utrecht/ states: 'The cost of the project is put at €1.3m...' and reckons that it has '...the ability to create enough electricity to power 40 homes.'

Doing my research, I think I may have pulled the price for this project from the wrong article.

https://www.theguardian.com/environment/2014/nov/05/worlds-first-solar-cycle-lane-opening-in-the-netherlands

40 homes at €25 per home, is still €300k less...

J

Edited to fix my maths.
Title: Re: The road to solar...
Post by: LittleWheelsandBig on 27 July, 2021, 10:53:09 pm
How much does a normal Dutch cyclepath cost for that length? Not too far off that, is my guess.
Title: Re: The road to solar...
Post by: JonBuoy on 27 July, 2021, 10:59:45 pm
https://www.dutchnews.nl/news/2021/07/worlds-longest-solar-panel-bike-bath-opens-in-utrecht/ states: 'The cost of the project is put at €1.3m...' and reckons that it has '...the ability to create enough electricity to power 40 homes.'

Doing my research, I think I may have pulled the price for this project from the wrong article.

https://www.theguardian.com/environment/2014/nov/05/worlds-first-solar-cycle-lane-opening-in-the-netherlands

40 homes at €25k per house, is still €800k less...

J

40 homes at €25k per house is €1m.  What is that €800k less than?
Title: Re: The road to solar...
Post by: quixoticgeek on 27 July, 2021, 11:02:22 pm
https://www.dutchnews.nl/news/2021/07/worlds-longest-solar-panel-bike-bath-opens-in-utrecht/ states: 'The cost of the project is put at €1.3m...' and reckons that it has '...the ability to create enough electricity to power 40 homes.'

Doing my research, I think I may have pulled the price for this project from the wrong article.

https://www.theguardian.com/environment/2014/nov/05/worlds-first-solar-cycle-lane-opening-in-the-netherlands

40 homes at €25k per house, is still €800k less...

J

40 homes at €25k per house is €1m.  What is that €800k less than?

300k less. I'm going to bed I am clearly not awake.

J
Title: Re: The road to solar...
Post by: fboab on 28 July, 2021, 10:36:29 am
There already been solar roads in France. I've ridden on it.

obviously a while ago (https://www.globalconstructionreview.com/news/frances-solar-road-dream-may-be-over-after-test-fa/)
Presumably the dutch design doesn't have to hold up to tractor traffic.
Title: Re: The road to solar...
Post by: ravenbait on 28 July, 2021, 10:45:55 am
I deal professionally with infrastructure. Having an asset in the control of a company or national agency where maintenance can be properly financed, scheduled, and, where necessary, enforced, is worth more than 300k.

Sam
Title: Re: The road to solar...
Post by: grams on 28 July, 2021, 10:55:49 am
Is the 40 homes claim year round after years of dirt and degredation, or on a really sunny day under ideal conditions when the panels are clean and brand new?

(It wouldn’t surprise me if it’s based on the gross rating of the bare panels without even the attenuation of the glass surface and without accounting for the far from ideal horizontal mounting)
Title: Re: The road to solar...
Post by: Cudzoziemiec on 28 July, 2021, 11:06:12 am
I deal professionally with infrastructure. Having an asset in the control of a company or national agency where maintenance can be properly financed, scheduled, and, where necessary, enforced, is worth more than 300k.

Sam
Shshsh! You might give Sustrans dangerous ideas!

Solar powered kissing gates on the cycle path?
Title: Re: The road to solar...
Post by: tatanab on 28 July, 2021, 11:09:13 am
There already been solar roads in France. I've ridden on it.
I rode a stretch several times at the 2017 Semaine Federale in Mortagne au Perche.  This was the road itself, so fully load bearing.
Title: Re: The road to solar...
Post by: ravenbait on 28 July, 2021, 11:45:17 am
Shshsh! You might give Sustrans dangerous ideas!

Solar powered kissing gates on the cycle path?

Sustrans and I haven't been on speaking terms for about 20 years, now.

Sam
Title: Re: The road to solar...
Post by: philip on 28 July, 2021, 11:45:54 am
It's 330m long and about 3m wide -- 40 houses gives about 25m2 per house. As rooftop panels that might give a 3-4 kW, but laid flat, under glass, with a rough, dirty surface it must be less than that. It's not enough for high power things like electric showers and hobs, it might even strugle to supply a kettle. The inhabit.com link posted earlier suggests a 100m path might power just 3 houses which sounds more plausible. The wikipedia page is not encouraging https://en.wikipedia.org/wiki/SolaRoad
Title: Re: The road to solar...
Post by: philip on 28 July, 2021, 11:52:09 am
I suppose 25m2 is comparable to the amount of panels fitted on a typical house roof, so it that respect the path could be considered as equivalent.
Title: Re: The road to solar...
Post by: Kim on 28 July, 2021, 11:58:08 am
There's a big difference between the area needed to meet the average consumption for a house, given sufficient storage and diversity to cope with peak loads, and the amount of capacity you'd need to actually power a couple of houses.

For this reason I think that the "could supply n houses" is a slightly less useful unit than the milliPirate-Ninja, and maybe it would be simpler if we all just used Watts.  File with London buses per Olympic swimming pool.
Title: Re: The road to solar...
Post by: Cudzoziemiec on 28 July, 2021, 12:01:42 pm
Another way to think of it might be "We're building a cycle path. Shall we surface it in tarmac, concrete, or solar panels? (Or for Sustrans, mud.)"
Title: Re: The road to solar...
Post by: philip on 28 July, 2021, 12:12:49 pm
If we ignore the peaks, how much would 25m2 of solar cycle path generate? If it can produce about a kW in favourable conditions it could produce 10kWh in a day, that might power a house.
Title: Re: The road to solar...
Post by: Kim on 28 July, 2021, 12:19:08 pm
Another way to think of it might be "We're building a cycle path. Shall we surface it in tarmac, concrete, or solar panels? (Or for Sustrans, mud.)"

That's certainly the logic, but you also have to factor in the alternative of building a solar roof over the cycle path, with cheaper, cleaner panels inclined at a more productive angle.  It'd be brilliant: Not only do you get free electricity to power some inadequate lighting and an audio-visual art installation, but the shade helps keep the mud slippery and the puddles full even in the peak of summer.

Or, more pragmatically, building a normal cyclepath and installing some solar panels somewhere else.
Title: Re: The road to solar...
Post by: Beardy on 28 July, 2021, 12:30:35 pm
Dave on EEV has done a few YouTube videos on solar roadways. He holds them in almost as much contempt as he does wireless energy startups.

Here are the two most recent
Spanish pavement (https://youtu.be/RIiiGReUZ3A)
US solar roadways (https://youtu.be/gmYVyp_gB_o)
Title: Re: The road to solar...
Post by: Cudzoziemiec on 28 July, 2021, 12:50:48 pm
Another way to think of it might be "We're building a cycle path. Shall we surface it in tarmac, concrete, or solar panels? (Or for Sustrans, mud.)"

That's certainly the logic, but you also have to factor in the alternative of building a solar roof over the cycle path, with cheaper, cleaner panels inclined at a more productive angle.  It'd be brilliant: Not only do you get free electricity to power some inadequate lighting and an audio-visual art installation, but the shade helps keep the mud slippery and the puddles full even in the peak of summer. pragmatically, building a normal cyclepath and installing some solar panels somewhere else.
You forgot that it would also provide a pigeon perch in the optimum position for shitting on cyclists.
Title: Re: The road to solar...
Post by: Wycombewheeler on 28 July, 2021, 02:09:13 pm
I suppose 25m2 is comparable to the amount of panels fitted on a typical house roof, so it that respect the path could be considered as equivalent.
I think the typical house with solar panels does not have 25m2 of panels.  I don't think the area of my roof is a large as that,  unless covering all faces,  which would be crazy,  very little sun falling on the north side.
Title: Re: The road to solar...
Post by: DuncanM on 28 July, 2021, 02:51:07 pm
The typical house install in the UK does not have 25m2 of solar panels. The average panel is rated around 300W, and is about 1m2 . IIRC, you need to apply to the DNO for permission if you want to install an array capable of more than 4.5kW peak, meaning you end up with about 14 panels or so. We have 15 on our house and because they are east/west the peak is probably around 3kW.
On a really good summers day, generation peaks around 28kWh. On really crappy winter days it can struggle to get to 1kWh.

There are other issues with sticking panels on the floor, like the effect shading has, and how the inverters can deal with it. I guess you would probably use micro-inverters so that each panel has it's own inverter, to avoid the effect where part of the roadway is in shadow so the whole thing isn't working properly, but this approach adds cost. 
Title: Re: The road to solar...
Post by: quixoticgeek on 28 July, 2021, 10:54:14 pm
The typical house install in the UK does not have 25m2 of solar panels. The average panel is rated around 300W, and is about 1m2 . IIRC, you need to apply to the DNO for permission if you want to install an array capable of more than 4.5kW peak, meaning you end up with about 14 panels or so. We have 15 on our house and because they are east/west the peak is probably around 3kW.
On a really good summers day, generation peaks around 28kWh. On really crappy winter days it can struggle to get to 1kWh.

Doesn't have 25m² of panels, but could. A 50m² house with a south facing pitched roof has 25m² of roof available.

A DNO is only required if you are exporting >4.5kW to the grid. If you are using the rest locally, then it's not a problem. This is also a UK specific requirement, in other locations it's different.

I heard a stat recently, but have been unable to confirm it, that in Australia, there is so much sun that panels on the south facing roof can yield more power than panels on a similarly pitched south roof in Germany. I need to confirm if that's true. Tho.

Quote
There are other issues with sticking panels on the floor, like the effect shading has, and how the inverters can deal with it. I guess you would probably use micro-inverters so that each panel has it's own inverter, to avoid the effect where part of the roadway is in shadow so the whole thing isn't working properly, but this approach adds cost.

Oh yes, I didn't get into that on my rants as I didn't want to get too technical. But yep, all those issues!

J
Title: Re: The road to solar...
Post by: jsabine on 29 July, 2021, 11:03:25 am
I assumed that was QG's point.
Title: Re: The road to solar...
Post by: canny colin on 29 July, 2021, 12:10:45 pm
I wonder what will happen if a truck goes astray and gets a wheel on to  a corner of the  panel / path . Dutch trucks do have high axel loading for on / off road use . 
Title: Re: The road to solar...
Post by: mrcharly-YHT on 29 July, 2021, 12:54:39 pm
Most of this ignores another problem with wind/solar/tidal; building a grid that can cope with fluctuations.

It is entirely possible to have a 'local area' grid that also exports power. However, this is not often what is configured.

A perfect example of this exists in the Outer Hebrides. Tons of wind power. Turbines all over; lots of community groups invested in them.

Then the grid connection to the mainland grid was severed. The turbines had to be turned off.
Consequences:

It will have taken 10 months to get the interconnector back up.

Have they learned from this?

No. There is a scheme to build several 180m tall turbines. Blade diameter 250m.
Title: Re: The road to solar...
Post by: ravenbait on 29 July, 2021, 01:02:47 pm
FWIW, people involved in infrastructure are VERY aware that the network just doesn't have the capacity to convert all power demands to renewables. What we do about it is another question entirely.

Sam
Title: Re: The road to solar...
Post by: DuncanM on 29 July, 2021, 01:14:00 pm
A DNO is only required if you are exporting >4.5kW to the grid. If you are using the rest locally, then it's not a problem. This is also a UK specific requirement, in other locations it's different.
I don't think it's possible to have >4.5kW generation capacity and limit the export so as to stay under that number for DNO purposes (legally, I'm sure it's technically possible).
You are absolutely right that it's a UK condition, and also that conditions in other countries may be much better suited to solar PV. One thing that people don't consider is that length of day is almost as important as sunshine - if the temperature gets too hot then the panels become less efficient.
Title: Re: The road to solar...
Post by: Kim on 29 July, 2021, 01:18:45 pm
Most of this ignores another problem with wind/solar/tidal; building a grid that can cope with fluctuations.

It is entirely possible to have a 'local area' grid that also exports power. However, this is not often what is configured.

A perfect example of this exists in the Outer Hebrides. Tons of wind power. Turbines all over; lots of community groups invested in them.

Then the grid connection to the mainland grid was severed. The turbines had to be turned off.
Consequences:
  • No income for community groups.
  • Power supplied by (very) dirty diesel generators.
  • Reduction in renewable power across Scotland

It will have taken 10 months to get the interconnector back up.

Have they learned from this?

No. There is a scheme to build several 180m tall turbines. Blade diameter 250m.

To their credit, the Universiy of Birmingham actually learned this lesson:  After the Great Selly Oak Substation Fire of 2012 the campus was without power for a couple of weeks, while their half-megawatt natural gas CHP station sat there uselessly.  They had to bring in portable diesel generators to supply each building individually so they could make them safe for public use (lifts, lighting).

They've since installed a modest diesel generator and the control gear needed to boostrap and synchronise the turbine in the absence of grid power.  I've even seen them testing it.

(Bet their IT infra is still a single point of failure, thobut.)

It's one thing being in the middle of a city and not being aware that your electricity supply all runs through a single duct under a live railway line.  If you're on an island, it seems ludicrous to rely on an interconnector like that.  No doubt it saves a few quid on black start capability.  Turbines make money; resilience wastes it.
Title: Re: The road to solar...
Post by: SoreTween on 29 July, 2021, 05:25:53 pm
The typical house install in the UK does not have 25m2 of solar panels. The average panel is rated around 300W, and is about 1m2 .
I think you're a bit high there, 200w per m2 is closer currently.
Title: Re: The road to solar...
Post by: DuncanM on 31 July, 2021, 07:39:36 pm
The typical house install in the UK does not have 25m2 of solar panels. The average panel is rated around 300W, and is about 1m2 .
I think you're a bit high there, 200w per m2 is closer currently.
Good point - the panels are 300W, but they are more like 1.5m to 1m