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Published on: May 5, 2026 / Updated on: May 5, 2026 – Author: Konrad Wolfenstein
Solar boom on highways? Forgotten photovoltaic areas: How 13,000 kilometers of highway are supposed to save the German power grid – Creative image: Xpert.Digital
Germany's highways are becoming the new linchpin of the energy transition. Along the approximately 13,000 kilometers of federal highways and a further 38,000 kilometers of federal roads lies a vast, long-overlooked potential of up to 300 gigawatts for photovoltaic systems. Fueled by drastically simplified permitting processes and new legal privileges, an unprecedented market for ground-mounted solar parks is currently opening up. Investors, project developers, and municipalities are sensing a lucrative opportunity on the roadside verges.
But the gold rush along the highways has a treacherous downside: While the market volume for ground-mounted solar installations is exploding, an unprecedented wave of bankruptcies is simultaneously sweeping through the solar industry. Negative electricity prices, years-long waiting times for grid connection, and a ruinous price war are bringing even established companies down. For investors and landowners, this environment is becoming a high-risk gamble. Anyone who is blinded by abstract gigawatt figures and makes mistakes in choosing partners or structuring contracts risks not only their return on investment—but the total loss of their capital. This article ruthlessly analyzes the true costs, the hidden risks, and the vital strategies for survival in the new solar boom along our highways.
Billions in potential, a wave of bankruptcies, and the most expensive mistake of the energy transition: Whoever chooses the wrong partner now will lose everything
Germany has a problem with available land. Every new solar power plant, every ground-mounted solar park has to justify itself – against agricultural interests, nature conservation regulations, and local concerns. It is all the more astonishing, then, that a huge, largely untapped potential was simply overlooked for decades: Germany's highways. Around 13,000 kilometers of federal highways and another 38,000 kilometers of federal roads crisscross the country, flanked by noise barriers, embankments, verges, and parking areas. These infrastructure corridors were largely inaccessible to solar energy until now – but that has fundamentally changed.
The Fraunhofer Institute for Solar Energy Systems (ISE) has calculated that transport infrastructure alone, which comprises five percent of Germany's land area, holds the potential for up to 300 gigawatts of additional photovoltaic capacity. For comparison, in April 2024, solar power plants with a total capacity of only 81.5 gigawatts were installed throughout Germany. The Federal Highway Research Institute (BASt), in its potential analysis commissioned by the Federal Ministry of Transport, arrived at a more conservative, but still enormous, figure for the areas directly adjacent to highways: 24 to 48 gigawatts of technically feasible capacity on roadside verges alone, plus 3.2 to 4.2 gigawatts on noise barriers, up to 1.2 gigawatts on parking areas, and 0.5 to 0.6 gigawatts on vertical noise barriers. All of this combined results in a total potential of over 54 gigawatts – and this is only the technically feasible capacity, not including the additional areas surrounding the corridors.
These figures have attracted attention in Berlin. The Federal Ministry for Digital Affairs and Transport has mapped a total of around 250,000 potentially suitable areas for solar energy generation along federal highways, thus making it clear that the motorway is not a niche topic for idea generators, but a central element of future energy supply strategies.
The decisive turning point came not from a technological innovation, but from a stroke of the legislature. With the Act on the Immediate Improvement of the Framework Conditions for Renewable Energies in Urban Planning Law of January 2023, ground-mounted photovoltaic systems along highways and multi-track railway lines were classified as privileged projects under Section 35 Paragraph 1 No. 8 of the German Federal Building Code (BauGB). What sounds bureaucratic has far-reaching consequences in practice: Within a corridor of up to 200 meters from the outer edge of the roadway, a development plan is no longer required. Project developers can apply for building permits directly, which significantly accelerates and simplifies the planning process.
Furthermore, the legislature has granted renewable energies the status of overriding public interest. This significant protected interest generally prevails over competing public interests in balancing procedures – a tangible advantage in permitting processes that previously had to be painstakingly fought for. While there is no direct preferential treatment in the 200- to 500-meter corridor, these areas are also eligible for subsidies under Section 48 of the Renewable Energy Sources Act (EEG) after a successful tendering process. With the expansion of this area, the developable land potential has increased to over 4.8 million hectares nationwide.
The 2023 Approval Acceleration Act supplemented this framework: It explicitly accelerated and simplified the expansion of photovoltaic systems on and along federal highways. At the same time, the regulation prohibiting the construction of systems within 40 meters of the roadway was relaxed – after individual review, the entire area up to 200 meters can be used. Germany has thus taken a very clear legal stance in favor of solar highways.
Paper and practice are two different things. Between a politically decided preferential treatment and the actual construction of solar power plants along highways lie numerous practical steps. The Autobahn GmbH des Bundes (Federal Highway Company), the state-owned company responsible for the planning, construction, operation, administration, and financing of the federal highways, has announced the next logical step: the creation of a nationwide register of all potentially usable areas and facilities under its ownership. This register is the fundamental prerequisite for ensuring that the development of this potential is structured and not haphazard.
The process is designed in two stages: First, Autobahn GmbH examines whether and where it can construct and operate the solar power systems itself, taking economic viability into account. The goal is ambitious: By 2040, the company aims to achieve climate neutrality in the maintenance and operation of the highways and will therefore gradually expand the use of photovoltaics. A first concrete step is the already completed 100 kWp solar power system on two roof surfaces of the Leverkusen traffic control center, which supplements the local electricity supply.
Where Autobahn GmbH has no need for the land itself, the right of use will be granted to interested third parties – municipalities, adjacent landowners, and investors. The necessary contract templates were finalized by the beginning of 2025. This mechanism is the key lever intended to channel private capital into the development of motorway corridors. This opens up a market for private project developers that was previously virtually closed – with all the opportunities and risks that a young, still incompletely regulated market entails.
The motorway section in the Garzweiler open-cast lignite mine area in North Rhine-Westphalia is considered a flagship project: Solar power plants are planned to be built along the A44n and A46 on noise barriers, windbreaks, and embankments. A feasibility study conducted by Drees & Sommer confirmed the economic viability of the 24 MW project, which will cover a length of 30 kilometers, and recommended moving into the planning and implementation phase. Another early pilot project on the A3 near Aschaffenburg – an approximately 890-meter-long and three-meter-high noise barrier with integrated photovoltaic modules – was completed in 2019 and has been operated by a private company for the past 20 years.
Investment dynamics in the German solar industry shifted fundamentally in 2024 and 2025. While total capacity expansion remained high – reaching a record high of over 16 gigawatts of new installed capacity in 2024 – the source of this capacity changed. Private rooftop systems for homeowners up to ten kilowatts plummeted by more than 50 percent in the first half of 2025 compared to the same period of the previous year, and commercial rooftop systems also declined by around ten percent, ground-mounted solar parks increased by approximately 25 percent. In 2025, a total of around 16.5 gigawatts of new photovoltaic systems were installed, and solar power's share of the electricity mix climbed to about 18 percent.
The driver of this shift is easily explained economically. Ground-mounted solar parks benefit from economies of scale, optimized orientation, lower specific installation costs for large systems, and a more transparent tendering market through the Federal Network Agency. In the most recent EEG tender round for ground-mounted PV systems in December 2025, by far the largest share of the awards – 125 awards totaling 1,150 megawatts – went to projects located along the verges of highways or railway lines. The tender volume was massively oversubscribed, with twice the amount of bids offered, illustrating the enormous market dynamics. The average volume-weighted award price was five cents per kilowatt-hour.
Solar power plants along highways offer an additional structural advantage: existing transport infrastructure creates a pre-existing social burden on the area, which significantly reduces conflicts of interest with residents and agriculture. Therefore, acceptance of solar-powered highway corridors tends to be higher than for new open-field solar parks on previously untouched land.
The potential is enormous, the legal framework is favorable, and political support is in place – yet solar power along highways is not a simple business. The devil is in the details, and those who are unaware of them can quickly lose their capital. Standard ground-mounted photovoltaic systems cost between €600 and €1,100 per kilowatt-peak (kWp) net, depending on size; for a one-megawatt system, this equates to around €850,000. Smaller rooftop systems cost approximately €1,600 to €1,800 per kWp, which is on average 15 to 25 percent cheaper than comparable ground-mounted systems.
However, specific additional costs arise on and along highways, which can significantly exceed these reference values. Covered structures over the roadway require massive supporting structures that can withstand wind and suction forces while simultaneously being protected from corrosion caused by traffic exhaust. Early preliminary calculations for highway canopies amounted to approximately €250 per square meter for the structural work alone – compared to around €125 per square meter for a ground-mounted solar park. Installation on noise barriers is more cost-effective, as the glass of the modules also serves as noise protection, and the cabling can be integrated into the supporting structure. The pilot project on the A3 near Aschaffenburg demonstrated precisely this synergy effect.
A roof project for a 35-meter exit ramp at the Munich-East interchange, operational since the end of 2025, generates approximately 210,000 kilowatt-hours of solar power per year, enough to supply about 70 households. This figure illustrates the scale: interesting, but still a long way off for industrial-scale energy transition. The economic viability depends heavily on the achievable electricity price – whether through direct grid feed-in, on-site use for highway operations, or long-term power purchase agreements (PPAs) with industrial customers.
One of the most insidious pitfalls of the solar boom along highways is a structural financing paradox: On the one hand, the market for large-scale ground-mounted solar installations is booming, while on the other hand, a considerable number of solar project developers are struggling for their economic survival. This apparent contradiction is explained by the fundamental transformation of the revenue structure that the sector has undergone in recent years.
The government-guaranteed feed-in tariff under the Renewable Energy Sources Act (EEG), with fixed rates over the entire financing period of typically 20 years, was long considered the epitome of planning security. It enabled bank financing at favorable conditions because cash flows were predictable. This model is increasingly being replaced by market-price-dependent direct marketing and Power Purchase Agreements (PPAs) – with contract terms typically of five to ten years, which are significantly shorter than the financing terms of the plants. This creates a gap: The initial contract term is financeable, but what happens afterward remains uncertain.
Negative electricity prices exacerbate this problem structurally. In the first half of 2025, around 28 percent of Germany's potential photovoltaic (PV) generation fell during periods of negative electricity prices on the exchange – a drastic increase compared to the same period of the previous year, when it was around 18 percent. Extrapolated to the entire year of 2025, this equates to approximately 790 hours with negative prices. The Solar Peak Act of February 2025 further intensified the situation: Since February 25, 2025, operators of photovoltaic systems with a capacity of two kilowatts peak or more no longer receive any compensation during periods of negative electricity prices, starting from the very first hour. At the same time, the capacity threshold above which this regulation applies was lowered from 400 kWp to 2 kWp – which also affects small systems.
New: Patent from the USA – Install solar parks up to 30% cheaper and 40% faster and easier – with explanatory videos! – Image: Xpert.Digital
The core of this technological advancement is the deliberate departure from conventional clamp mounting, which has been the standard for decades. The new, more time- and cost-effective mounting system addresses this with a fundamentally different, more intelligent concept. Instead of clamping the modules at specific points, they are inserted into a continuous, specially shaped support rail and held securely in place. This design ensures that all forces – whether static loads from snow or dynamic loads from wind – are distributed evenly across the entire length of the module frame.
More information here:
While the ground-mounted solar market is booming, the industry is experiencing a historic wave of consolidation. Companies such as Eigensonne, Amia Energy, Enersol, Wegatech, and Envoltec have filed for insolvency. Sun Contracting filed for insolvency at five subsidiaries with liabilities of approximately €47 million. MEC Energy, an established developer of solar parks, had to file for insolvency under self-administration at the Düsseldorf District Court in September 2025. Energieinsel GmbH from Oberkrämer, which won the Brandenburg Future Prize as recently as 2019, ceased operations in January 2026.
The German Solar Association predicts a continuation of the market consolidation: Those providers who cannot adapt their cost structures quickly enough to the new market reality will disappear. The situation is particularly dire for 2025, as PV installations in the first half of the year, at just under 7.1 gigawatts, were almost 15 percent lower than in the same period of the previous year, despite overall structural market growth.
The reasons for this paradoxical simultaneity of boom and bust are multifaceted. A ruinous price war, fueled by cheap module imports from China, has eroded the margins of many companies. Construction cost increases of over 30 percent within two years, rising grid connection costs, and uncertain subsidy policies are exacerbating the situation. The structural shift towards large-scale ground-mounted and highway projects is hitting many companies traditionally focused on rooftop installations hard – their core business is shrinking even as the overall market expands.
For investors, municipalities, and landowners, this wave of insolvencies is not an abstract industry phenomenon. It has very concrete consequences: down payments are lost, construction sites are at a standstill, warranties are no longer enforceable, and maintenance contracts are not being fulfilled. Projects that are close to being connected to the grid can be delayed by months or even years due to the insolvency of the project developer. Grid connection costs and permits are often not transferable in such cases.
Even if the site, financing, project developer, and permits are all in place, a solar park next to a highway can fail at one crucial point: the grid connection. Across Germany, project developers and operators report delays of months to years for grid connection. Commitments take time, specifications vary, and capacity is lacking. The transmission system operator 50Hertz announced in July 2025 that its grid connection capacity for project launches between 2025 and 2029 was exhausted and that no new grid connection commitments for projects before 2029 were possible.
The principle by which grid connection applications are processed is particularly frustrating for well-prepared projects: it's a case of "first come, first served" – the postmark, not the project's maturity, is the deciding factor. A fully developed, bankable highway project can thus be pushed aside by a poorly planned application submitted earlier. The first solar package promised simplifications and greater standardization for grid connections, but consistent implementation in the distribution networks is still pending.
Large, open-field solar parks along highways, often with capacities of ten to 50 megawatts, require grid connection to substations in the medium- or high-voltage network. Proximity to the highway offers a strategic advantage: in Germany, power and communication lines frequently run alongside major roads, which can tend to shorten distances to grid connection points. However, this advantage is not universally available – and where it is lacking, grid connection costs of several hundred thousand euros can jeopardize the economic viability of a project.
All the risks described – negative electricity prices, waves of bankruptcies, grid connection problems, regulatory uncertainties – converge on one point: choosing the right partner. And this is precisely where the most costly mistakes are made in the solar highway business. Because a highway project typically involves significantly more stakeholders than a simple rooftop installation: landowners (the highway company, possibly the state or municipalities), permitting authorities, EPC contractors (engineering, procurement, construction), grid operators, financing partners, direct marketers or PPA buyers, and potentially operating companies.
Each of these parties brings its own interests, capacity limitations, and insolvency risks. An EPC contract—in which a contractor handles all planning, procurement, and turnkey construction, bearing the cost, schedule, and performance risks—theoretically offers good protection for the client. In practice, however, its value depends entirely on the creditworthiness and operational capacity of the EPC partner. An EPC contractor who files for insolvency drags the client down with them: ongoing construction projects are halted, warranties become worthless, and often supply bottlenecks arise because the insolvent partner has failed to make advance payments to suppliers that were already due.
Contract partners for solar highway projects are therefore subject to special due diligence obligations. Key verification criteria include: a proven track record in comparable infrastructure projects, sufficient equity capital and creditworthiness, bank guarantees or completion bonds, independence from individual subcontractors, and clearly defined repurchase and decommissioning obligations at the end of the operational period. Those who fail to conduct this due diligence systematically risk losses not only during the investment phase but also throughout the entire operational life of the project.
Power Purchase Agreements (PPAs) are considered the instrument of choice for mitigating the structural disadvantage of variable market prices in solar highway projects. A PPA is a long-term electricity purchase agreement between the plant operator and an electricity buyer – usually an industrial company or an energy supplier – at a pre-agreed price. For ground-mounted solar power plants that no longer receive feed-in tariffs under the German Renewable Energy Sources Act (EEG) or have consciously chosen to forgo them, the PPA is the key to securing revenue. Energy suppliers like EnBW emphasize that PPAs create investment security and prevent plants that have reached the end of their subsidy period from being taken offline.
However, PPAs also have inherent weaknesses that are particularly significant in motorway projects. First, the currently typical PPA terms of five to ten years are considerably shorter than the financing terms of the plants themselves, which are generally 20 years. This means that after the first PPA expires, the investor is left with a largely new power plant but without guaranteed revenue – in a market where negative electricity prices are becoming more frequent. Second, many PPAs had to be reduced in price by around 20 percent in 2024 compared to the previous year because of the general decline in electricity prices. Third, the increasing frequency of negative wholesale electricity prices, where the plant cannot sell electricity or would even have to pay to do so, calls into question the fundamental viability of traditional PPAs without storage solutions.
The solution lies in combined structures: PPAs plus battery storage make it possible to buffer electricity during periods of low prices and sell it during periods of high prices. Storage PPAs, in which a third-party provider builds and operates a battery storage system next to the PV system at its own expense, are increasingly being marketed as a standalone product. Such systems are economically viable from a system size of around 900 kWp – precisely the scale at which many highway corridor projects operate.
The fundamental question that arises amidst all the euphoria surrounding solar highways is: Is this a structurally sustainable market or a regulatory-induced bubble that will collapse at the next political shift? A more nuanced analysis reveals a more complex picture.
Several factors support the structural viability of the project. Its technical potential is undisputed and well-documented scientifically. The regulatory simplifications – preferential treatment, no zoning plan required, overriding public interest – are enshrined in law and difficult to reverse. European climate targets necessitate the further expansion of renewable energies, regardless of short-term federal policy. The share of renewable energies in Germany's gross final energy consumption rose to 23.8 percent in 2025, an increase of 1.3 percentage points – the direction is clear. And the Federal Autobahn GmbH, as a state-owned company, is a landowner with exceptional institutional stability, which significantly reduces the land risk compared to private lessors.
There are also compelling arguments against investing without careful consideration. The ongoing wave of bankruptcies demonstrates that the market is not yet stable and that oversupply in certain segments can lead to ruinous competition. Experts predict that negative electricity prices will remain a significant risk until at least 2030, before large-scale storage and flexible demand mitigate this effect. The ongoing debate about abolishing feed-in tariffs in favor of pure direct marketing is creating uncertainty for smaller plants. Furthermore, the grid package presented by the CDU-led Federal Ministry for Economic Affairs and Energy in 2026 caused considerable unease within the industry, as it would grant grid operators greater freedom in connecting new plants and introduce construction cost subsidies for generation facilities as well.
Given this complex environment, practical recommendations are needed that go beyond general platitudes. For municipalities interested in motorway corridors within their boundaries, a GIS-based potential analysis of the actually privileged areas within the 200-meter corridor is recommended as a first step, combined with an inquiry with the responsible distribution network operator regarding grid connection capacity. Both pieces of information together determine whether a project is even economically feasible.
For investors and project developers, the key is this: preferential treatment is the starting point, not a free pass. Crucial factors include the creditworthiness of the land lessee (in this case, Autobahn GmbH as a state-owned entity, and therefore very stable), guaranteed grid connection before the Letter of Intent, the technical quality of the EPC partner with a proven track record, and a viable revenue structure – at least a ten-year PPA plus subsequent market simulation taking into account hours with negative electricity prices. In a market currently experiencing a wave of insolvencies, a project without a bankable completion guarantee from the EPC partner is simply irresponsible.
For landowners receiving lease offers from project developers, the following applies more than ever: credit checks of the provider, rights of withdrawal in the event of a lack of construction progress, minimum lease payments regardless of electricity generation, and clear decommissioning obligations at the end of the operating period are not negotiable options, but minimum standards. The case of the Sun Contracting Group with liabilities of around 47 million euros and the collapse of MEC Energy vividly illustrate what happens when advance payments are made and the partner becomes insolvent.
The solar potential along German highways is real, substantial, and increasingly accessible. The regulatory framework has been significantly improved, the official land registry is taking shape, and the massive oversubscription in the tender rounds demonstrates the availability of private capital. However, the potential of an area is not the same as the return on a project. The entire complexity of the project business lies between these two factors: grid connection, partner selection, revenue structure, financing, negative electricity prices, and contract design.
The solar boom along highways rewards those who professionally manage this complexity – and punishes those who ignore it with the full force of a dysfunctional market. The ongoing market correction is therefore not a tragedy, but a necessary selection process: it weeds out those players who focused on hype rather than substance and makes room for those who truly understand the business. In such a market, choosing the wrong partner doesn't just cost returns – it can wipe out all the invested capital.
Anyone wanting to establish a sustainable position in the solar highway business needs one thing above all: ruthless objectivity in evaluating partners, projects, and revenue structures. The land may be tempting, the potential may sound enormous – but without the right partner, a secure grid connection, and a robust financing structure, even the most beautiful stretch of highway will ultimately be nothing more than an expensively leased embankment.
Konrad Wolfenstein
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© May 2026 Xpert.Digital / Xpert.Plus – Konrad Wolfenstein – Business Development
