The short answer is that solar roadways largely failed. Every high-profile pilot in France, the Netherlands, the US and China produced far less electricity than promised, suffered physical damage, or was shut down and removed. The technology has not proven viable for busy roads, and the early optimism around it is not supported by the outcomes.
Solar roadways embed photovoltaic cells under a tough, textured, transparent top layer (glass, resin or “transparent concrete”) so the surface can carry traffic. The concept is appealing: use the vast area of roads, pavements and car parks to generate clean energy. In practice, the story has been one of low yields, high costs and durability problems.
How solar roads work
Solar roads place solar cells flat on the ground rather than tilted towards the sun. This creates immediate disadvantages. In an interview reported in 2019, Wattway put the loss from the horizontal position at about 10%, with a further loss of about 20% from traffic and shading.
The panels are built to carry heavy loads, so the cells sit under thick, textured protective layers. Some designs add extra features, such as embedded LEDs for road markings, heating elements to melt snow, or sensors.
The cost gap between conventional and road-integrated solar is stark. At the time of the first major rollout, AFP reported that Wattway’s panels cost around 17 euros per watt-peak, compared with 1.30 euros for a large rooftop installation. That ratio of roughly 13 times is a central economic hurdle for the technology.
Real-world examples
Wattway (Colas), Tourouvre-au-Perche, France
Inaugurated on 22 December 2016 by Environment Minister Ségolène Royal, the Tourouvre pilot was a 1 km stretch of road covered with 2,800 m² of solar panels. Funded by a 5 million euro state subsidy, it was intended to power the town’s street lights. AFP gave the expected output as 280 MWh a year, though one later report cited 560 MWh; the sources conflict.
The results fell short. In the first 12 months, the road generated 149.4 MWh, about half the target. By February 2019, after 792 days, the cumulative display showed 250 MWh. About 5% of the roughly 2,500 slabs were replaced in the first year, the speed limit was cut to 70 km/h after noise complaints, and the panel supplier SNA went into liquidation.
Over six years, total output was 366.2 MWh, about 61 MWh a year. By 2022 it powered the equivalent of only three homes. Problems included subsidence, dirt fouling, noise and delamination, and ten versions of the slab were tried. The council voted to dismantle the road on 15 February 2024, and demolition began on 27 May 2024. Wattway accepts the surface is unsuited to busy, high-speed roads but still calls the trial a success, and has refocused on cycle paths, car parks and pavements. As a road, the trial failed.
SolaRoad, Krommenie, Netherlands
Opened in October–November 2014, the SolaRoad pilot was a cycle path with an initial 72 m section; the total pilot cost €3.5 million. After six months, the developers said they expected more than 70 kWh/m² a year, but this was an extrapolation, not a measured multi-year result. First-year output was 9,800 kWh, according to a SolaRoad press release.
Durability was a persistent issue. About 1 m² of coating detached in December 2014, the top coating was replaced in October 2015, and a crack appeared in an improved element in February 2017. By January 2020 a “bad road surface” warning sign was up. The path closed on 25 November 2020 and was resurfaced with normal asphalt.
Heavier traffic tests fared worse. Two pilots, a 100 m bus lane in Spijkenisse and a 50 m section in Haarlemermeer, opened in March 2019 and closed within about a week because of top-layer failures. The Spijkenisse pilot was ended in July 2019 because repair was not possible.
Solar Roadways (Brusaw), Sandpoint, Idaho, US
Scott and Julie Brusaw’s company raised $2.2 million in a 2014 Indiegogo campaign, the site’s most-backed campaign at the time. It also received US DOT/FHWA small business research funding: $100,000 in 2009, $750,000 in 2011, a further contract in December 2015 and another $750,000 in 2016. Its pilot in Sandpoint opened on 30 September 2016 in a pedestrian plaza, not a road. It consisted of 30 hexagonal panels covering about 14 m² and cost about $60,000, mostly from state and city grants.
Performance was poor. Only five of the 30 panels were working in October 2016. Output averaged about 0.62 kWh a day in late March 2017, ranging from 0.26 to 1.06 kWh. In August 2018, the best month, output averaged about 0.25 kWh a day. For comparison, a typical single home solar panel makes about 1.45 kWh a day.
The pilot was shut in December 2018 after LED fading and snow-heating problems. A replacement was promised for 2019 at no cost to the city, but we found no public output data after that. A planned Solar Roadways sidewalk in Missouri stalled in 2017 after contract talks failed, and we found no report that it was ever installed. In 2014, ExtremeTech estimated the cost of covering all US roads at about $56 trillion, based on Brusaw’s price of $10,000 per 12 × 12 ft section.
Jinan solar expressway, China
At the end of December 2017, a 1 km test section of the Jinan ring expressway opened, with “transparent concrete” over PV supplied by Shandong Pavenergy. Peak capacity was 817.2 kW, and the developer projected about 1 million kWh (1 GWh) a year. That was a projection, not a measured result.
The road faced immediate physical risks. About five days after opening, a strip roughly 10–15 cm wide and 1.85 m long was cut out by thieves, and seven nearby sections were damaged. Police investigated. Some outlets later reported the road closed, others that it was repaired, and we found no published measured output.
What the numbers say
- Low yield: By our estimate, Tourouvre averaged about 22 kWh/m² a year, against Wattway’s own planning figure of 80 kWh/m². The estimate is rough, because in later years only a few hundred metres had working panels. All 30 Sandpoint panels together made 0.25–0.62 kWh a day on average, less than half of what one typical home panel produces. These surfaces had a very low capacity factor.
- High cost: Wattway’s initial cost per watt was roughly 13 times that of rooftop solar. Critics estimated SolaRoad’s cost at about $0.86 per kWh, assuming $1,200/m² installed, 70 kWh/m² a year and a 20-year life.
- Comparison with standard solar: IRENA puts the 2024 global weighted-average levelised cost of electricity (LCOE) for new utility-scale solar PV at US$0.043/kWh, with total installed costs around US$691/kW. In the UK, DESNZ estimated large-scale solar commissioned in 2025 at about £41/MWh (in 2021 prices). Solar roads, by contrast, sit at a far higher cost per unit of energy.
Is there a solar roadway market?
You will find market-research figures for “solar roadways” and “solar highways”, but no credible government, IEA or IRENA estimate. The paid reports disagree wildly: their 2024 estimates are more than 20 times apart, partly because “solar highway” in some reports covers panels beside roads, canopies and lighting rather than road surfaces. We therefore do not quote a market size.
Limitations and honest assessment
Durability: Roads are harsh environments. SolaRoad’s coatings failed repeatedly, and its heavy-traffic pilots failed within about a week. Wattway suffered subsidence and delamination and needed slabs replaced.
Efficiency: Flat panels lose output compared with tilted ones, and traffic shading and dirt reduce it further. At Tourouvre, dirt fouling was cited as a problem.
Safety and noise: Noise complaints at Tourouvre led to the speed limit being cut to 70 km/h. In 2014 a US DOT engineer said the agency could not say the Solar Roadways surface would be safe for vehicle traffic.
Theft and vandalism: Part of the Jinan surface was cut out and stolen within days of opening.
Other ideas for turning surfaces into generators, such as solar paint or piezoelectric floors, face a similar test: whether the energy produced justifies the cost.
The UK angle
The UK has experimented with solar in transport infrastructure, but mostly in forms that keep panels out of the path of traffic.
In March 2004, Solarcentury installed an 11 kWp, 50 m solar noise barrier on the M27 near Portsmouth for the Highways Agency, expected to produce about 9,500 kWh a year. The Netherlands has since scaled up the idea: a 400 m long, 5 m high barrier with bifacial panels on the A50 at Uden began generating in December 2018 and supplies about 40–60 households.
Car parks are another option. Portsmouth City Council’s Lakeside North Harbour scheme was planned in 2022 with about 4.5 MW of solar PV, 3.55 MW of it on car-park canopies, plus a 2 MW battery. Canopies keep panels away from vehicle wear, which makes them a far more practical option than paving roads with glass.
Frequently asked questions
What are solar roadways and how do they work?
Solar roadways are roads, paths, pavements or car parks with photovoltaic cells under a tough, transparent surface such as glass, resin or “transparent concrete”. They generate electricity from sunlight while vehicles or people pass over them, and some designs add LEDs, heating or sensors.
Did solar roadways fail, and why?
Yes, the major pilots failed to meet expectations. They produced far less electricity than predicted, partly because flat panels lose output and traffic shades them. They also suffered physical damage, including detached coatings, subsidence, delamination and dirt, leading to repeated repairs and early removal.
What happened to the Solar Roadways company in Idaho?
Solar Roadways received government research grants and $2.2 million from crowdfunding, but its Sandpoint plaza pilot produced only a fraction of standard solar output. It was shut in December 2018 after LED and heating problems. A replacement was promised for 2019, but we found no public output data or independent evidence of progress since.
Is there a real solar roadway market?
There is no reliable, independent estimate. Paid market-research figures disagree by more than 20 times for the same year, because definitions differ and some include roadside panels, canopies and lighting. The market for in-road solar surfaces remains niche and unproven.
Are solar driveways or solar pavements worth it?
Solar driveways and pavements face the same yield and durability problems as solar roads. Solar Roadways once promoted driveways, but we found no evidence of a commercial driveway product on sale. For homeowners, conventional rooftop solar remains the proven option.
What works better than putting solar panels in roads?
Placing panels beside or above roads rather than in them. Solar noise barriers, such as those on the A50 in the Netherlands and the M27 in the UK, keep panels away from traffic. Solar car-park canopies, such as the scheme planned in Portsmouth, also avoid vehicle wear while providing shade.