There was also a news report about a swimming solar field on the surface of a lake a few days ago. Interesting that one of the major "innovations" in solar tech now seems to be political - i.e. finding spaces where PV can be installed without bothering anyone.
Still, it paints an interesting picture that no government would care about angry residents or potential alternative uses when building a road or prospecting for oil or coal (remember the Hambach and Lützerath events in Germany where entire villages were cleared because there was coal to strip mine).
Meanwhile, for wind we're still debating whether the safety zone to the next inhabitated building should be 1km or 2km...
I must criticize this on the grounds that it is ugly, but then almost everything that is built these days is ugly.
Secondly, what genius decided to make it a flat roof? Flat surfaces are the absolute worst both in capturing the most sunlight in temperate latitudes and in terms of dirt and snow removal. Even a 45° angle would mean a lot of the dust, leaves and snow will just tumble down or get washed down by the next rain, whereas flat surfaces are literally encrusted within months.
'Solar roads' are uniformely a miserable idea. They are eco-theatre.
You want solar, put it in an uninhabited ground-level unobstructed serviceable cheap location near the grid outside of town. Because, wires can transmit electricity anywhere it's needed.
Elaborate structures for solar cost more than the panels these days. Never build them. At most, tilt them to the local lattitude. If tempted to do more, instead buy more panels. Power per dollar works out better.
Yeah, the solar road is a bad idea. The solar roof or solar car park, on the other hand, is a more appealing idea. Many places are running out of "cheap" locations, that's why housing is so expensive.
> wires can transmit electricity anywhere it's needed.
Well .. yes, if you build the wires. A surprising amount of projects are getting held up on grid connection grounds. Whereas embedding the panels near urban demand reduces that problem.
Yes, definitely. In the early 00's I put up an elaborate system with two axis trackers, it was very nice but fragile, not nearly as sturdy as a regular rack would have been and the extra money spent on the trackers would have been better spent on more panels, even at the prices back then. So today this is a complete no brainer (assuming you have the space, but tracking panels use more space than stationary ones so even then it probably won't work to your advantage).
This!
Even so my local utility is putting in tracking solar projects. Got to be eco-theatre as well. And they track over the day! not over the year. Here the sun varies 42 to 78 degrees to the south, but the panels are flat overhead (90 deg). Again, all that mechanism for so little gain.
> This! Even so my local utility is putting in tracking solar projects. Got to be eco-theatre as well.
They probably did the math, and at that location, the ROI for a single-axis tracker was better than the ROI for fixed panels.
> And they track over the day! not over the year.
This probably means it's a single-axis tracker, which points east in the sunrise and west in the sunset. To track over the year it would need a second (north-south) axis, but the ROI for that probably wasn't better than a single-axis tracker.
> Again, all that mechanism for so little gain.
A single-axis tracker isn't that complicated (and a single axis with a single motor can move a whole row of panels at once), so even if the gain is small, it can be more than enough to pay for the mechanism.
A single-axis tracker isn't expensive, but solar panels have gotten very cheap.
They've gotten so cheap that this Texas company claims that it's cheaper to buy more panels and lay them on the ground rather than using a rack to get them at a better angle.
> They probably did the math, and at that location, the ROI for a single-axis tracker was better than the ROI for fixed panels.
They probably didn't do the math. If they had they would have installed fixed panels. Panels are so dirt cheap that you'd have to come out more than 60% ahead on the cost of the tracker and that's never ever going to happen. Just add more panels.
I have 50 of them now in some pretty bad orientations, ~ 100 KWh on a good day and if I had half that many on trackers it wouldn't even come close. And on bad days the only thing that you want in a solar installation is surface area. Peak performance isn't interesting at all, and tracking at best gives you 20 to 25% more power at the price of the tracking mechanism being much more bulky than panels, panels shading each other when used with trackers so you'll use your space far less efficiently, fragility and finally complexity. Don't use trackers.
The single axis could have been used to tilt toward the sun, instead of always year-round being tilted away from the sun (straight overhead). Got to be a bigger benefit than catching some oblique early morning or late evening rays. Missing out on the core of the power-generating day (11 to 1) by being pointed in the wrong direction is gotta be suicide to efficiency.
You want a roof, build a roof. You want solar, build a solar farm. You should no more put solar over other structures than grow radishes up there. It's a terrible idea from every point of view (except eco-theatre).
That kind of frontier attitude "if we need more land we'll just build a longer road into the desert" won't fly anywhere within a thousand kilometers from where that bike path roof is built.
The "solar roadways" nonsense from a few years ago was about putting solar panels in the road surface itself, which is a terrible idea for many reasons. Putting solar panels above the road is only a bad idea if the cost is prohibitive relative to putting them elsewhere.
Think of this as a cheap-ish roof first, and a solar generator second. If all your cycle commuters switch mode when the weather isn't super nice they don't reduce the capacity needs for driving or public transit at all. Keeping bike commuters on bikes in inconvenient weather can be very valuable, compared to the cost of keeping all that idle-unless-rainy capacity. The success threshold of this project is recouping the premium over a corrugated sheet roof. And once you start considering north-south connections an angled roof stops looking that obviously superior, it might well not be worth the effort. You can't just do south-facing rows like a standalone installation of your primary goal is keeping the rain and snow out.
It looks super jank. Nice to get some shade though, for sure. Are solar panels so cheap now that they just didn't bother designing something that would hold them at a 45 degree angle while still offering the same amount of shade?
Seconded. I have a bunch of panels at a very low angle (12 degrees) due to siting constraints and they foul up pretty quickly. And that's already much better than what's in TFA.
I wonder how much a few simple maintenance bots could help, basically a solar roomba that opportunistically travels along the roof, zig-zagging as far in a day as much or little in a day as it's energy supply allows. Something like that clearly can't work for a small installation, but when a city has a network of roofed bike paths, you'd expect first glimpses of economy of scale. Could nicely hit a sweet spot between doable, futuristic, real-life utility and not served by commercial offerings for a university project.
Likely not worth it. Even when they look pretty fouled up they still work very well, less than 5% off peak performance and the first good rainsquall and they're back to new state.
At ~€1m total price, it's about 3500€/kW, which is roughly 2-3 times the equivalent rooftop solar price (but this likely includes paving the bike path, frame structure, etc).
And this doesn't count the fact that you're providing shade for cyclists as well. I wonder how expensive it would've been to make a simple roof just for shade; I imagine your value per meter goes up significantly considering that.
Given Freiburg weather that's a definitive "help". It's not like they get huge snowdrifts accumulating over months that need to get cut away or anything like that.
Apart from the fact that this prototype is very ugly, some limitations come to mind.
- Maintenance without blocking the bike lane. Does this require a separate access road?
- Will this work when any trees are nearby? Falling branches are likely to cause damage and block the sun.
- How does this work when buildings are nearby? You will block all the light? I'm having trouble imaging how this will look good in a more dense area - not the mention the extra width required on the sides of the bike path will be hard to get where space is at a premium (cities).
All this seems to point to a rather limited use case: bike lanes in places with few buildings and few trees, and sufficient spacing around the structure to facilitate maintenance access. That presumably means: in sparse industrial zones near edges of cities (as pictured, I suppose).
Which leads to another question: how many sparse industrial zones in Germany actually have bike 4m wide bike paths?
One of the reasons why I bike to work every day is to get some DIRECT light from the sun. Many kinds of research have shown the positive sides of it.
If I live in a hotter (and humid?) place, i.e., middle-east or SEA, I would love the idea. But, to have that in a colder place, i.e., nordic, I'll make sure to pick other routes without the shades. :-)
If the top image of the article is real, then I guess illumination would'nt be a major problem, especially in the morning and evening when the sun is low.
As the summer period is finally here, the sun rises super early in the morning and sets late, around 8/9 pm. That is already outside my commuting schedule, if I may argue. :-)
This is much smarter than what they did in the Netherlands, where the panels are literally underneath the bike path, so bikes ride on them. They are constantly covered in filth and are not running anywhere close to their full capacity, irrespective of weather.
I live on the Front Range in Colorado where we have the Santa Fe trail, almost entirely without tree cover.
The sun is brutal here at 6500+ feet, and I would use this every day if it were available since there aren't many bike paths with protection from the sun.
When structures like this is built is a lifetime cost taken into account? I'm wondering if after a while it's going to fail or prove too expensive to maintain.
Still, it paints an interesting picture that no government would care about angry residents or potential alternative uses when building a road or prospecting for oil or coal (remember the Hambach and Lützerath events in Germany where entire villages were cleared because there was coal to strip mine).
Meanwhile, for wind we're still debating whether the safety zone to the next inhabitated building should be 1km or 2km...