Solar Roads: Will They Illuminate the Future Roadways?
Senna Surjaputra
Abstract: The roadways which usually made of concrete or asphalt might be replaced by
solar roads in the near future. The solar roads are road surfaces that convert sunlight
into electricity. Not only are the solar roads generating clean energy, but they also
increase the drivers’ and pedestrians ‘safety. However, there are still a lot of challenges
about solar roads, such as their cost, efficiency, and maintenance.
Introduction
Solar energy is a popular source of clean energy. Solar energy can be captured using solar
panels and converted to electricity. Currently, the common places to install solar panels
are either on the roof or on empty land. So, the roof and the empty land are modified only
for capturing solar energy. However, recently some engineers have an idea to put solar
panels on the roadways and those roadways are called solar roads. One of the most
promising solar roads projects is called the Solar Roadways. Engineers Julie and Scott
Brusaw are the founders of the Solar Roadways [1]. They are able to raised more than
$2.2 million from indiegogo.com for their solar roads project and they also receive some
fund from the government to develop their project. According to the Brusaw, the
founders of the Solar Roadways, it is better to have solar roads rather asphalt roads [1].
The Brusaws think that rather than simply using roads as hard surfaces for vehicles, it is
better to have roads which have a lot benefits. There are around 4 million miles of paved
roads in USA and each year the road need maintenance. If solar panels were installed on
the roads, the roads would be able to pay for themselves by generating electricity [1]. Not
Surjaputra 2
only generating electricity, the Brusaw’s Solar Roadways has other benefits, such as
increasing safety. Although there are still some challenges for the Solar Roadways to be
mass-produced, there would be more benefits if solar roads replace the asphalt roads.
The Main Components in Solar Roads and Their Functions
Solar Roads are constructed from many panels of the Solar Roadways. The main
components of Solar Roadways are tempered glass, solar panels, LEDs, weight sensors,
and heaters.
Solar Panels and Technology Behind Them
A solar panel is a set of solar cells, which are electrical devices that convert the energy of
light to electricity. Basically, the solar cells work in two steps [2]. First, the
semiconducting materials in solar cells, such as silicon, absorb the photons from the
sunlight that hits the solar cells. Then, the absorbed photons make the electrons excited
knocking them loose from the atoms in semiconductors materials. Those freed electrons
are the electricity that flows in the electrical circuit [2].
Tempered Glass, the Benefits, and Its Texture
Solar panels, which are mainly electrical circuits, themselves are not suitable to support
any weight in top of them, such as that from cars and trucks driving over them. The
solution for the solar road is to cover solar panels with tempered glass, so they are
capable of withstanding the weight of humans or even heavier things, such as heavy
vehicles [1]. Tempered glass is a type of safety glass produced by raising the temperature
Surjaputra 3
to extremely high (almost 1200 degree Fahrenheit) and immediately cooling the glass [3].
The result is a strengthened glass which is at last four times stronger than regular glass.
Another benefit of using tempered glass is the safety of it, since when broken, tempered
glass shatters into small granular chunks instead of shards. Pedestrians need to worry
less, because the pebble-like pieces will not cut their feet [3]. The broken pieces of
tempered glass will not cause a flat tire too. Lastly, to deal with traction the tempered
glass is textured to such a way that a vehicle going 80 mph is able to fully stop within a
required distance [1].
LEDs and Weight Sensors
Have you ever imagined how the roadways will look like in the future? Will the
roadways shine bright like the roadways in the Tron: Legacy movie (Figure 1) ?
Figure 1: Roadway in Tron: Legacy Movie
That is what will going happen if solar roadways replace the traditional asphalt roadways.
Besides looking cool, the LEDs are programmable [1]. LED is the abbreviation of light-
Surjaputra 4
emitting diode. LEDs are used in the Solar Roadways, because they consume less energy,
they have longer lifespans, and they are smaller in size than regular light source. Instead
of using paint, the LEDs can be programmed to mark road lines, parking lines, and street
signs. Programmable LEDs also mean the road marks can be changed within minutes
without repainting [1]. Moreover, the LEDs increase the safety when driving at night and
in rain by illuminating the road and providing more vision. Thanks to the weight sensors,
the solar roads can detect if there are any stationary heavy things on the roads, such as
falling trees and boulders [1]. In these cases, the LEDs will warn the drivers by giving
LEDs texts to slow down. The solar roads can be used to make recreation parks too. The
parks can be programmable and reprogrammable to the users’ preferences. These include
basketball courts, tennis courts, hockey courts, and whatever the users can imagine [1].
Figure 2 is the computerized look on how the road looks like using Solar Roadways.
Figure 2: The Solar Roadways on Roads
Surjaputra 5
Heaters
Snow is one of the hazard to use the solar roadways in the North. Luckily, heaters can be
installed inside the solar roadways. The solar roads will heat up just a few degrees above
freezing when the snow falls [1]. The heated roads will prevent ice and snow on the
roads, since the ice and snow will melt away as shown in Figure 3.
Figure 3: Unheated and Heated Panels
No more snow and ice in the streets means there will be less traffic, accidents, and
injuries. People do not need to shove their driveways too. The states also can save some
money, since snow removal is no longer needed anymore. For people who like sports,
they can now run, jog, and ride their bicycle in any season [1].
Amount of The Electricity Produced by Solar Roadways
Besides being used to power the LEDs and heaters themselves, the produced electricity
can power up a lot of differences things [1]. Producing the electricity is the main benefit
of the solar roadways and this electricity is a clean energy. According to the Brusaws, if
Surjaputra 6
their solar roads replace most of the roadways in the United States, the solar roads could
produce at least three times the electricity that is currently used in the United States [1].
Challenges
While these solar roads can generate three times of electricity used in the United States,
they are not with their limitations. Maintenance, efficiency, and cost are the main
challenges.
Maintenance
All electronic devices have their own lifespan, including solar panels, LEDs, and heaters.
The lifespan or life expectancy on electronic devices means that those devices will be
unusable or not working properly in the expected number of years. According to
ennergyinformative.org, most manufacturers of solar panels guarantee that their products
will produce not less than 80% of original rated power before 25 years [4]. That means
the solar panels might need to be replaced after 25 years. The best LEDs have general
lifespan of 50,000 hours, so the LEDs will need to be replaced in less than 6 years [5].
Moreover, as stated in the dialymail.co.uk, a lot of LEDs do not meet their lifespan claim.
We can also expect the same things from the solar panels, LEDs, and heaters, which can
be broken at anytime. Maintaining the texture in the tempered glass is needed too. Just
like the texture in our shoes soles, the tempered glass texture will wear out over time
because of the friction. Thus, the solar roads need to be maintained regularly to check if
Surjaputra 7
the solar panels, LEDs, and heaters still work properly and if the texture in the tempered
glass still safe enough for cars to drive on the solar roads.
Efficiency
Aside from the solar panels’ life span, the problems come from their efficiency too. Solar
panels efficiency is the ratio of amount of light converted to the electricity [6]. The most
efficient solar panels right now are around 44% efficient. However, those solar panels do
not have feasible price to be used in public [1]. The efficiency of solar panels, which are
reasonable to be used in public, is 18.5%.
Cost
All of those maintenance and efficiency problems actually are all about the cost. How
much is the cost to replace the solar panels or LEDs or heaters? How much is the cost to
maintain and replace the textured tempered glass? Can we afford the solar panels with the
high efficiency? The biggest problems are might be the cost of production and
installation. Brusaws write, “The real question may be: What will be the cost if we don’t
implement the Solar Roadways?” [1].
Future Developments
If the engineers will develop more efficient solar panels in the future, the production cost
of solar roads will greatly reduce and of course the solar roadways will produce a lot
more electricity. Since the solar roadways are made of electronic devices, there is also a
possibility for the engineers to make a special lane in the solar roads for the electric
Surjaputra 8
vehicles to charge wirelessly. Another possible use for solar roadways is for security [1].
Since the solar roadways are pressure sensitive, they can detect if someone is present on
the solar roads panels.
Conclusion
In a nutshell, solar roadways may be the future of the roadways, because solar roadways
generate clean energy, promote the safety of the drivers and pedestrians, and have a lot of
possibilities for the future developments. On the other hand, there are still many
challenges for solar roadways, such as the maintenance, efficiency, and cost of the solar
roadways.
Surjaputra 9
References
[1] Solar Roadways. Online. Available: http://www.solarroadways.com/intro.shtml
[2] Gil Knier. How Do Photovoltaics Work?. Online. Available:
http://science.nasa.gov/science-news/science-at-nasa/2002/solarcells/
[3] Tempered vs. Non-Tempered Glass, What's the Difference?. Online. Available:
http://glasstopsdirect.com/news/tempered-vs-non-tempered-glass.html
[4] M. A. Maehlum. (2014, May 7). The Real Lifespan of Solar Panels. Online.
Available: http://energyinformative.org/lifespan-solar-panels/
[5] (2014, January 26). The Great LED Lightbulb Rip-off: One in Four Expensive 'longlife' Bulbs Doesn't Last Anything like as Long as the Makers Claim. Online.
Available: http://www.dailymail.co.uk/news/article-2546363/The-great-LEDlightbulb-rip-One-four-expensive-long-life-bulbs-doesnt-like-long-makers-claim.html
[6] Why Solar Efficiency is Important. Online. Available: http://us.sunpower.com/solarresources/performance-reliability/solar-efficiency/