Solar Roadways: Still Just A Fantasy?

Dear EarthTalk: Are solar roadways still a “thing”? Why don’t we have them everywhere now helping us keep our EVs charged up and rolling?

—Jason M., Shelton, CT

In 2014, the concept of solar-powered photovoltaic road panels that could collect sunlight and convert it into usable energy went viral when the Idaho-based company Solar Roadways heralded it as a solution to the global energy crisis. The company proposed developing solar-powered panels to form smart roads, highways, and parking lots. These solar roadways would theoretically produce electricity while providing other smart features for the cars and trucks that drove on them.

According to Solar Roadways, the benefits of their solar roadways would be more than just the production of clean energy. The roads would provide heating to melt off snow and ice and would use LEDs for lighting and to warn about road obstructions. Solar roadways could also charge electric cars through inductive charging, meaning that EVs would be charged just by driving on the solar roadways.

Since its founding in 2006, Solar Roadways has been pushing the endless benefits of its product. The viral 2014 video “Solar FREAKIN’ Roadways” brought significant attention to the company. After successfully generating hype for so many years, what has Solar Roadways achieved so far?

Early Projects and Setbacks

Between 2016 and 2017, news circulated that a Solar Roadways installation on Route 66 in Missouri was in the works. However, the project was not for a roadway at all, but for a solar sidewalk alongside the highway. Whatever the case, the contract fell through for unspecified reasons before a single road panel was ever laid.

The only place their product has been used is in their pilot project: a small 150-square-foot installation of walkway in their hometown of Sandpoint, Idaho, installed in 2016. The initial rollout was underwhelming, suffering a fire in its electrical system and then failing to melt snow that fell upon it.

Current Implementations

A solar roadway in Peachtree Corners, Georgia, is apparently the only one currently operational in the U.S. It was installed in late 2020 using WattWay road panels. However, the project is very limited in scope and occupies a narrow strip within an autonomous vehicle test lane.

Challenges to Implementation

So why aren’t solar roadways being installed across the U.S.? Despite the possible benefits of solar roadways, implementation at scale would be quite a challenge. For one, since solar roadways would lie flat on the ground, they wouldn’t be ideal for maximizing their exposure to direct sunlight. On a regular solar farm, the panels are angled towards the sun to maximize efficiency, and even then, the typical solar panel can only use about 20 percent of the energy that the sun produces. It would be more efficient to run the solar panels alongside the road rather than on top of it. Creating solar roadways that can withstand heavy vehicle pressure while still letting in sunlight has been another difficult task. Also, there are safety and noise concerns. And the LEDs which would act as traffic lines and obstruction warnings are difficult to see during the day. Solar roadways are also incredibly expensive compared to regular old pavement.

Global Attempts and Lessons Learned

While Solar Roadways has not implemented the concept as of yet in the U.S., there have been a few projects abroad that have attempted to turn the concept into reality. In 2016, the French company WattWay completed a 0.62-mile installation in Normandy, France. The project was met with excitement but quickly fell flat as the road generated little energy and was unable to withstand normal traffic wear and tear. A similar thing happened in Jinan, China, when in 2017 Chinese engineers constructed their own 0.62-mile solar roadway. It was closed within a week due to traffic damage and the theft of road panels.

Despite the setbacks, the journey of Solar Roadways and other similar ventures provides valuable lessons and insights into the potential and challenges of integrating solar technology into our infrastructure.

However, when it comes to comparing the power production of solar road panels to traditional solar panels, several factors contribute to the significant difference in efficiency:

  • Less Sunlight: Unlike rooftop systems, solar road panels can’t be tilted to achieve the best solar panel angle, which means an energy loss of 20% or more.
  • Shading: Solar roadways will experience shading from passing vehicles, surrounding buildings, vegetation, and debris like dust and leaves. Even a small amount of shade has a major impact on solar panel production.
  • Excess Heat: Since they’re built into the road, the ground panels can’t be cooled by air circulation. This will reduce solar panel efficiency, which drops as panel temperatures exceed optimal levels.

According to expert engineering analysis, solar roadways produce just one-third the power of solar panels of equivalent capacity in a solar power plant. This makes it clear that, while innovative, solar roadways currently lag behind traditional solar installations in terms of power efficiency.

Creating solar roadways that can withstand heavy vehicle pressure while still letting in sunlight has been another difficult task. Engineers have thus far been unable to make a solar road panel that can successfully withstand the pressure of heavy vehicles while remaining transparent enough to let sunlight in. This dual requirement presents a significant engineering challenge, as the materials need to be both durable and efficient in capturing solar energy. The current designs have yet to meet these demands, leading to ongoing research and development in this area.

Also, there are safety and noise concerns. And the LEDs which would act as traffic lines and obstruction warnings are difficult to see during the day. Solar roadways are also incredibly expensive compared to regular old pavement.

While Solar Roadways has not implemented the concept as of yet in the U.S., there have been a few projects abroad that have attempted to turn the concept into reality. In 2016, the French company WattWay completed a 0.62-mile installation in Normandy, France. The project was met with excitement, but quickly fell flat as the road generated little energy and was unable to withstand normal traffic wear and tear. A similar thing happened in Jinan, China, when in 2017 Chinese engineers constructed their own 0.62-mile solar roadway. It was closed within a week due to traffic damage and the theft of road panels.

Back in the U.S., Solar Roadways had planned an installation on Route 66 in Missouri between 2016 and 2017. However, this was not for a roadway but a solar sidewalk alongside the highway. Unfortunately, the contract fell through before any panels were installed. The only place their product has been used in the U.S. Is a small 150-square-foot pilot project in Sandpoint, Idaho, installed in 2016. This project faced significant issues, including a fire in its electrical system and failing to melt snow.

Current U.S. Projects

There is one operational solar roadway in the U.S. Located in Peachtree Corners, Georgia. This installation, completed in late 2020, uses WattWay road panels and occupies a narrow strip within an autonomous vehicle test lane. Despite its limited scope, this project is currently the only functional solar roadway in the country. However, no performance data has been shared, making it hard to assess its success.

In summary, while international attempts at solar roadways have faced significant challenges, the U.S. Has seen limited but noteworthy efforts to explore this innovative technology.

The Future Outlook for Solar Energy Capacity in the U.S.

The future of solar energy in the U.S. looks incredibly promising. As technology advances, solar panels are becoming a cornerstone in energy production.

Key Projections:

  • Cost-Effective Solutions: Modern solar plants are emerging as some of the most affordable options for energy generation, rivaling traditional sources.
  • Rapid Expansion: Projections indicate that the total solar capacity in the U.S. is set to triple between 2022 and 2027.

Why This Matters:

This dramatic growth is driven by both technological advancements and increasing investment in renewable energy. The expansion of solar capacity means more sustainable energy options will be available, potentially lowering costs for consumers and reducing greenhouse gas emissions.

In summary, the U.S. is on the cusp of a major solar revolution, poised to significantly boost its solar energy capacity in the coming years.

While these false starts don’t bode well for the future of widespread solar roadways, EV charging roads may still be an option. In 2021 the state of Michigan pledged to complete a wireless charging road by 2023. The leading company in the project, Electreon, says that the EV charging road is complete, and will open to the public in the next few years after a testing period. The emergence of EV charging roads would promote the usage of electric cars and provide some reprieve from cars’ fuel emissions.

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