How do Solar Roadways Work?
Solar roadways capture the sun’s energy as it hits road surfaces and converts it to usable power. This clean, renewable energy is used to power road infrastructure, stored for later use, or fed into the grid for transmission.
For quite some time now, solar-powered roadways have been a hot topic for good and not-so-good reasons.
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A good part of the buzz is people supporting it-arguing that it has the potential to produce clean energy on otherwise untapped road spaces.
The other side of the technology hype is people (including energy experts) defining it as a failure due to the problems facing it such as dirt, mechanical damage, and shading.
All in all, solar roadway projects are booming with more and more smart highways being constructed thanks to this technology.
Our goal in creating this guide is to help you understand more about this infrastructure integrated PV technology.
You’ll get answers to the following questions as you read this post:
- How are solar roadways installed and how do they work?
- What are the most successful solar roadways projects?
- How can solar roadways improve our roads?
- Are solar roadways a failure?
What are Solar Roadways?
Solar roadways, also known as solar roads are solar PV cells integrated into road systems. They’re a type of infrastructure-integrated PV system, now a common solar technology trend.
Roads cover around 0.5% of the earth’s surface. Solar roadways are expected to tap into this free land to produce clean, renewable energy.
Now let’s discuss how this is accomplished.
Design/Installation/ Working Principle of Solar Roadways
Solar road panels are designed to mimic the characteristics of traditional asphalt, while at the same time producing electricity.
In terms of design characteristics, solar road panels should be:
- Strong and tough to support the weight of the heaviest vehicle on the road.
- Grip or traction equal to that asphalt to assure safety when driving or walking on them.
- Flexibility to allow for installation even in the most difficult corners and the tightest curves.
Here are the materials that make a typical solar road panel installation:
The base layer: The base layer consists of insulation material. It serves as the main structural element. This layer also forms a grip with the road construction materials.
Middle layer: This is the solar panel’s section. The middle layer also houses wires and cables needed to connect all components of the installation.
Top layer: The top layer is typically tempered glass. It allows the solar panels to be safely driven/walked on.
Capping: This is the uppermost layer used to offer extra protection to the solar cells and the connections. The most commonly used capping is transparent concrete. In order to provide the traction that conventional roads offer, the layer must be rough enough.
The working principle of solar road panels is no different from that of conventional modules.
Solar road panels collect sunlight and convert it to the energy that can be used to power a good deal of road infrastructure. The most feasible components being signage, traffic lights, and traffic cameras.
The power produced by solar tiles on roads can also be tapped in charging stations for electric vehicles.
Lastly, excess energy can be stored alongside the solar roads or fed into the grid and transmitted to power the surrounding areas.
The middle layer of solar roads is equipped with a microprocessor board for monitoring power and signals from the road. The board is also responsible for controlling any additional components or elements integrated into the solar panels, such as heating elements.
Solar Roadways Production Capacity
Moving on to how much solar roadways can produce, here is a general observation from the already rolled out projects:
Currently, the production of many experimental projects is still below the expected standard capacity.
Metrics of WattWay, the first world solar roadway project done in France, was a clear indication of the low cost-effectiveness of solar roads. The experts in charge of the project expected to generate around 767 kilowatt-hours per day but the installed solar panels only produced 409 kilowatt-hours in the first year of operation.
Even so, the low production can still be rectified with design improvements and optimization of installation designs.
With the majority of solar road projects still in the experimentation stage, it’s not surprising the total production capacity is still very low.
According to The Ray, the 48 South US states have 52,000 acres of free roadside land that can be used to generate power.
If this space is leveraged, it’s possible to produce 36TWh annually which is more than 9 times the power consumed in the US. In 2020, the total power consumption in the US was 3.8TWh.
The value of this amount of power is around $4 billion per year.
Solar Roadways Price
Going with the same project mentioned above- Wattway- solar roadways are currently not only pricey but also uneconomical.
Wattway’s cost was $20 (€17) per KWh which is 20 times what solar roof installation costs -$1.53 (€1.3).
Please note: As with production capacity, solar roadways may become more economically and economically feasible if design and installation improvements are done.
Examples of Popular Solar Roadways Projects
Solar roadways have their critics, but they’re still being tested in various locales across the world. Here are examples of well-known solar road projects globally:
| Project Name | Location/ Country | Year of Installation | Cost | Area/ length | Solar panels used | Company | Production capacity | Energy uses | Quick Fact |
| Wattway | Tourouvre, France | 2014-2016 | $5.2 M | 2,880 m2 1km | Wattway | Construction Giant Colas | 280MWh per year | Power street lights | World’s first solar roadway project |
| SR3 pilot installation | Sandpoint, Idaho | 2016 | $60,000 | 14m2 | SR3 | Solar Roadway | 0.25KWh per day | Power an information center | First solar roadway project in the US |
| China Solar Highway | Jinan, China | 2018 | $2.7 M | 5875m2 1km | Pavenergy | Qilu Transportation Development Group | 1GWh per year | Delivered to nearby areas | Solar roadway installed on 3 lanes |
| Sola Road | Krommenie, The Netherlands | 2014 | $4.135 M | 72meters | Sola Road | TNO, Dynniq and Ooms Civiel | 50-70 KWh per m2 per year | Charge EVs and guide cyclists | World’s first bike path |
| Clean energy from the pavement | Astana, Kazakhstan | 2017 | Anonymous | 4.6m2 | Platio | Platio | 11.7KWh per day | The materials are 9% recycled plastic | Charge EVs, Power a nearby office building |
As evident from the table above, most of these projects are small-scale.
So, for this technology to be rendered feasible and practical, it must be given time to advance from the experimental stage.
Are Solar Roadways a Failure?
As you review the above table, I am sure the following question is running through your mind:
What happened to solar roadways?
I’m sure if you’ve followed the topic of solar roadways even for the shortest time, you’re familiar with the myriad of negative speculations about how it’s a joke and not practical.
Some have even gone to a point of dubbing this technology a green scam.
But what is the real truth about the practicality and feasibility of this technology?
From an expert’s angle, solar roads are not a failure; they’re just not yet fully optimized to perform their role under stressful road conditions.
Mechanical stress, dust, and shading of the solar modules appear to be the most significant obstacles for this invention.
However, you can almost be sure that all the problems associated with solar road tiles can be resolved with improvements in design and installation procedures.
Solar Roadways as a Method of Preventing Ice/Snow Accumulation
In the US 24% of all weather-related crashes occur on icy, snowy, and slushy pavements. Additionally, winter road maintenance takes up to 20% of state DOT maintenance budgets.
Solar roadways have great potential to counter these issues.
A functional solar panel is typically ice and snow-resistant. When heat from the sun hits the surface of a module, it’s distributed across the entire surface melting any accumulated snow. That’s why solar panels rarely get covered in ice.
If a more focused method of dealing with ice and snow on roads is needed, solar road panels can be integrated with heating elements. One benefit of this integration is that the panels themselves will produce the electricity needed to power the heating elements.
Are Solar Roads Beneficial to the Environment?
With the renewable energy from solar panels, it is possible to replace the need for use of fossil fuels.
There are significant environmental effects associated with fossil fuels, including global warming, air pollution, and water pollution.
Shifting to clean, renewable solar energy is a big plus for the environment.
How Solar Roadways can be made Efficient and Cost-effective
Design changes
Improving the design for road solar panels will solve the durability issue and thus increase the period in which solar roads will collect sunlight and produce power.
Installing solar road tiles in suitable places
The biggest problem facing solar roads is the poor selection of the installation areas.
Installing solar panels right on the section where vehicles always pass is outright absurd.
Installers of solar roadway panels should focus on the following places when deciding where to install them:
- Bike trails
- Open roads
- Walkways
- Roadside
How Solar Roadways Can Contribute to Development of Smart Roads
LED light for lanes and signages
With LED light, roads can be marked digitally. This eliminates the need for the frequent painting of roads as well as the cost of powering digital signages powered by the grid.
Housing cables and wires
In order to modernize our roads, various components need to be wired together. Solar panels on the road surface provide a perfect platform where the connecting wires can be run.
Powering road emergency systems
Just like with lanes and signages, the electricity from solar roadways can be used to power road emergency systems.
Benefits of Solar Roadways
Production of clean solar energy
Solar tiles on roads harness sunlight and convert it to clean power that can be used to run road infrastructures such as street lights and traffic lights.
Even better, the power can be used to charge electric vehicles.
In the event that solar power is produced in excess, it can be fed into the grid. One great benefit of solar roadways- grid integration is that transmission distances are greatly reduced.
Improved look of roads
When properly installed on roads, solar tiles can add beauty to the surface. A good example is the bike lane in the Netherlands with LED lights to guide cyclists. The lights create a whole beautiful aura, especially at night.
Enhanced road safety
A solar roadway’s top layer is rough enough to assure good traction, which allows for safe driving/ walking.
Disadvantages of Solar Roadways
Durability problems
While solar road tiles are built to withstand as much vehicular pressure as traditional asphalt would do, the continuous stress eventually leads to mechanical damage.
Consequently, this leads to a reduced lifespan of solar roads.
On this account, solar panels fail to hit the longevity of conventional PV modules that can last 20-30 years.
Low Power Production Efficiency
There’s no doubt that this is the biggest hurdle to this technology.
With vehicles always passing on solar panels, there’s significant blockage of sunlight and definitely great mechanical damage due to the weight of the cars (Usually, the damage is in the form of micro-cracks).
These two factors, in addition to the general dirty road condition, negatively impact the production efficiency of solar roadways.
Interferes with the routine maintenance of roads
Roads require frequent maintenance- sometimes even expansion.
With solar panels covering a road, this can be a challenging task to perform.
Solar Roadways Conclusion: Are they Worth the Investment?
Since you now have a better understanding of solar roadways, you may wonder:
Are they worth the investment?
Currently, solar panels may seem like a not-so-worthy investment. But hear me out; the technology has not yet clocked its prime time.
Solar roadway technology is just at its revolutionary humble beginning, and people who make fun of it might be surprised by the impact it’ll have in the future.
As long as solar road tiles are improved design-wise and installed in the right sections, they’ll eventually make a worthy investment.