Cologne-Dünnwald solar park will become the energy hub of the future – Cologne's largest solar power plant is being built

Large solar power plant in Cologne-Dünnwald actively shapes urban energy transition

Cologne is taking a significant step towards the energy transition. One of the city's largest photovoltaic plants is planned for the Dünnwald district, setting new standards for local energy supply and serving as a model for the energy transition in urban areas. This project by RheinEnergie impressively demonstrates how ambitious climate protection plans can be put into practice.

Technical dimensions and performance

The planned photovoltaic plant in Dünnwald, with an installed peak capacity of 35 megawatts, will be among the most powerful solar parks in North Rhine-Westphalia. This impressive capacity corresponds to an electricity production that could theoretically supply around 11,000 households with climate-neutral energy. The plant will be built on an area of ​​approximately 33.5 hectares, located directly adjacent to the A3 motorway and along the railway line to Leverkusen.

The scale of this project becomes particularly clear when compared to other solar parks in Germany. With a peak capacity of 35 megawatts, the Dünnwald plant even surpasses Rheinenergie's previous largest solar park in Mecklenburg-Western Pomerania, which has a peak capacity of 32 megawatts. This size corresponds roughly to the energy needs of a small town and underscores the project's strategic importance for regional energy supply.

Location choice and geographical advantages

The choice of location in Dünnwald follows proven principles of sustainable land use. The site is strategically located east of the A3 motorway and makes optimal use of its proximity to existing infrastructure. This location offers several advantages: firstly, the proximity to transport routes minimizes the impact on the landscape, and secondly, the existing infrastructure facilitates the technical connection of the plant to the power grid.

The selected areas are owned by the city and are currently used for agriculture. Local farmers can continue to cultivate their fields until the planned start of construction in November 2025, ensuring a socially acceptable transition. This transitional arrangement demonstrates that even large-scale energy projects can take existing land uses into account.

Legal framework and approval procedures

The Cologne City Council has already set the decisive course for the project. In a closed session, the transfer of the city-owned land to Rheinenergie in exchange for corresponding lease payments was approved. The lease agreement is for a term of 25 years from commissioning, with an option to extend for a further five years.

Particularly noteworthy is Rheinenergie's comprehensive assumption of responsibility. The company bears not only the costs for planning, construction, and operation of the plant, but also for all necessary compensatory measures for environmental impacts and for complete dismantling after the contract ends. This arrangement ensures that no environmental contamination will occur after the plant's operational phase and that the land can be returned to its original use.

Rheinenergie as a driving force of the energy transition

The Dünnwald project is part of a comprehensive expansion strategy by RheinEnergie, which aims to increase its renewable energy plant capacity from approximately 230 megawatts to 600 megawatts by 2035. This ambitious goal demonstrates the company's commitment to the energy transition and the decarbonization of the energy supply.

Rheinenergie already boasts considerable experience in the field of photovoltaics. The company operates 28 photovoltaic plants across Germany on open land and rooftops, with a total installed capacity of approximately 57 megawatts peak. In addition, the company owns 26 wind farms with 107 turbines and a combined installed capacity of over 172 megawatts.

A particularly innovative aspect of RheinEnergie's strategy is the integration of battery storage systems. At the company's largest solar park in Mecklenburg-Western Pomerania, a battery storage system with a capacity of seven megawatt-hours has been installed for the first time. This technology makes solar power available even outside of daylight hours and contributes to grid stability.

Economic dimensions and financing models

The economic viability of solar parks has improved considerably in recent years. Modern ground-mounted photovoltaic systems can now achieve levelized costs of electricity (LCOE) of only 4 to 6 cents per kilowatt-hour. These low costs make solar power one of the cheapest forms of energy production and enable profitable projects even without government subsidies.

A typical solar park the size of the Dünnwald plant can generate annual returns of between 5 and 8 percent. These returns make photovoltaic projects attractive not only from a climate policy perspective, but also from a business perspective. Each hectare of solar park can be expected to produce approximately one million kilowatt-hours of electricity annually, generating revenues of around 60,000 euros per hectare.

Today, the financing of such large-scale projects is increasingly achieved through innovative models. In addition to traditional feed-in tariffs, long-term power purchase agreements (PPAs) are gaining in importance. These often allow for higher remuneration than statutory subsidies and create planning certainty for all parties involved.

Technological innovation and efficiency improvements

Modern photovoltaic systems benefit from continuous technological advancements. The efficiency of solar cells has improved significantly in recent years, while production costs have simultaneously decreased. High-quality solar modules now achieve efficiencies of over 20 percent and come with warranties of 25 years or more.

Developments in intelligent control technologies are particularly interesting. Modern solar parks are equipped with sophisticated monitoring systems that enable optimal operation. Artificial intelligence helps to maximize yield and identify maintenance needs early on.

Rheinenergie relies on proven partners from the solar industry for its projects. For example, Goldbeck Solar, a company with extensive experience in large-scale photovoltaic projects, was commissioned to build the solar park in Mecklenburg-Vorpommern.

Environmental impacts and biodiversity

A widespread myth claims that solar parks have negative environmental impacts. However, scientific studies actually show that well-planned photovoltaic systems can even have positive effects on biodiversity. When intensively used agricultural land is converted into extensively managed solar parks, biodiversity can even increase.

Ground-mounted photovoltaic systems generate approximately 30 times more electricity per year than biogas plants on a comparable area. This enormous efficiency advantage demonstrates how land-saving solar energy is compared to other renewable energy sources. Furthermore, the foundations of the solar modules are designed to cause minimal soil sealing and can be removed without leaving any residue after the system's operational life.

Fencing off solar parks creates protected habitats for small mammals and ground-nesting birds. By foregoing fertilizers and pesticides, specialized plant species can establish themselves on these areas, species that cannot find a habitat in intensive agriculture. Studies show that in Germany, 70 to 95 percent of the area of ​​solar parks can be used to promote biodiversity.

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At the heart of this technological advancement is the deliberate departure from conventional clamp fastening, 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. This design ensures that all forces occurring—be they static loads from snow or dynamic loads from wind—are evenly distributed across the entire length of the module frame.

More about it here:

• Clicking instead of screwing: This ingenious system builds solar parks 40% faster and revolutionizes the energy transition

Energy policy significance for North Rhine-Westphalia

The Dünnwald project fits into North Rhine-Westphalia's ambitious energy strategy. Germany's most populous state aims to double its installed wind and solar power capacity from the current 17 gigawatts to at least 34 gigawatts by 2030. This doubling of renewable energy capacity in just six years presents a formidable challenge that can only be met through projects like the one in Dünnwald.

Currently, ground-mounted photovoltaic systems with a total capacity of approximately 535 megawatts are in operation in North Rhine-Westphalia. The contribution of the Dünnwald project would increase the installed capacity in NRW by more than 6 percent. This demonstrates the supra-regional significance of the Cologne initiative.

The state of North Rhine-Westphalia has recognized that the energy transition can only succeed if all available potential is utilized. In addition to wind energy, where North Rhine-Westphalia is already a national leader, solar energy is also to be massively expanded. Municipal energy suppliers like Rheinenergie play a key role in this.

Area potential and future developments

Germany has considerable land potential for expanding photovoltaic capacity. Studies by the Öko-Institut show that space for 287 gigawatts of solar power is available on the verges of highways and railway lines, above parking lots, and on industrial and commercial sites alone. This significantly exceeds the German government's expansion target of 200 gigawatts by 2040.

These figures show that the expansion of solar energy does not necessarily have to lead to conflicts with agriculture. Only a very small amount of agricultural land needs to be used for conventional solar parks. At the same time, innovative concepts such as agrivoltaics open up new possibilities for combining energy production and agricultural use.

Theoretically, 13 million hectares of land are available in Germany for dual use with photovoltaics, which corresponds to 37 percent of the country's total area. This enormous potential demonstrates that the energy transition, even with ambitious expansion targets, will not fail due to a lack of land.

Citizen participation and social acceptance

Public acceptance of energy transition projects is a crucial factor for success. Municipal energy suppliers like Rheinenergie have a structural advantage here, as they are locally based companies and enjoy trust and strong local ties. Profits from such projects remain in the region and benefit the local economy.

Innovative participation models can further increase acceptance. In other regions, citizen energy cooperatives have proven successful, enabling local residents to directly benefit from the energy transition. Direct marketing agreements with local companies also create economic added value in the region.

The city of Cologne has already launched extensive programs to promote citizen-owned photovoltaic systems. With subsidies of up to €2,500 for photovoltaic systems and up to €1,300 for battery storage, the city supports private households in switching to solar energy. These programs demonstrate that the energy transition is understood as a task for society as a whole.

Technical challenges and solutions

Operating large solar parks presents specific technical challenges. The fluctuating feed-in of solar power requires intelligent grid management systems and flexible marketing strategies. Rheinenergie has developed significant expertise in this area through its own trading company, Rheinenergie Trading.

Modern solar parks are increasingly being combined with battery storage systems to compensate for fluctuations in solar power production. Rheinenergie has entered into a cooperation with SMA subsidiary Altenso to jointly develop projects with several hundred megawatts of battery storage capacity. The first joint project is a large-scale battery storage system with a capacity of 64 megawatt-hours in Lower Saxony.

The integration of storage technologies opens up new business models. Battery storage systems can be used not only to shift the timing of electricity feed-in, but also to provide system services such as frequency control and voltage stabilization. These additional revenue streams significantly improve the economic viability of the projects.

Climate protection impact and CO2 savings

The climate protection impact of the Dünnwald solar park is considerable. A photovoltaic system with a peak capacity of 35 megawatts can generate approximately 35 to 40 million kilowatt-hours of electricity annually. With a CO2 emission factor of around 400 grams per kilowatt-hour for the German electricity mix, this corresponds to annual CO2 savings of 14,000 to 16,000 tons.

Over the plant's 25-year operating period, CO2 savings will amount to approximately 350,000 to 400,000 tons. This corresponds to the annual emissions of about 75,000 passenger cars. These figures illustrate the significant contribution that individual projects can make to achieving climate protection goals.

Rheinenergie has set itself the goal of supplying its customers entirely with climate-neutral energy and heat by 2035. The Dünnwald project is an important step towards this goal. Since 2022, the company has been supplying its residential and commercial customers exclusively with green electricity from European renewable energy plants.

Future prospects and scalability

The Dünnwald project is just the beginning of a comprehensive transformation of the energy supply in the Cologne region. The city's climate protection monitoring has identified further potential sites for photovoltaic projects. A second project, located near the A555 motorway in Cologne-Rondorf, is already in the planning phase.

The scalability of such projects is impressive. If only a fraction of the identified potential areas were used, the installed solar capacity in the region could be significantly increased. Studies show that Germany could theoretically cover many times its electricity needs with photovoltaics.

Innovative technologies such as floating solar power plants on bodies of water or agrivoltaic systems above agricultural land offer further expansion potential. These technologies are still in the market introduction phase, but have the potential to significantly increase the land-use efficiency of solar energy once again.

Economic stimulus for the region

Large energy projects like the solar park in Dünnwald not only generate clean energy but also provide economic impetus for the region. During the construction phase, local companies are contracted for excavation, cabling, and assembly work. Long-term operation requires regular maintenance and servicing, which can also be carried out by regional service providers.

The lease payments to the city of Cologne strengthen municipal finances and create leeway for further infrastructure investments. At the same time, the local economy benefits from affordable and climate-friendly electricity. Particularly energy-intensive companies can reduce their energy costs and improve their carbon footprint through long-term electricity supply contracts.

The expansion of renewable energies makes the region less dependent on fossil fuel imports and creates local added value. These regional value creation effects are an important side effect of the energy transition and contribute to the region's economic development.

The project in Cologne-Dünnwald exemplifies the transformation of the German energy system. It demonstrates that ambitious climate protection goals can be achieved through concrete projects and that the energy transition can be not only an ecological but also an economic success story. The combination of technological innovation, economic viability, and societal benefits makes such projects pioneers for a sustainable energy future.

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The heart of ModuRack 's innovation is its departure from conventional clamp fastening. Instead of clamps, the modules are inserted and held in place by a continuous support rail.

More about it here:

• NEW: ready -to -mount solar systems! This patented innovation accelerates your solar construction massively

From industrial roof PV to solar parks to larger solar parking spaces

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