Hollandse Kust Noord offshore solar project (HKN1)

Pioneering the world’s first offshore solar farm within an offshore wind farm

NYMPHEA AURORA

As part of the Hollandse Kust Noord (HKN) project by Crosswind – a joint venture between Shell and Eneco – Oceans of Energy is delivering the fabrication, full EPCI and Asset Management scopes of the world’s first large-scale offshore solar farm within an operational offshore wind park. With a water depth of 25m and 1500 solar panels, the system is engineerd to survive and thrive in harsh North Sea conditions. This is backed by over four years of proven offshore performance (from the NS1 and NS2 systems). The system is expected to be fully comissioned offshore in Q3 2025.

The project is the first and largest offshore solar farm in the world to be installed, connected, and operated within an offshore wind farm. With offshore solar added to offshore wind, it is possible to also produce energy on sunny but less windy days and hence increase the utilization of the infrastructure. The solar panels are placed in-between the offshore wind turbines, combining for efficient use of sea space. Crosswind’s Hollandse Kust Noord project is an innovative offshore wind park that uses cutting-edge technologies to improve the flexibility of offshore renewable energy systems.

NYMPHEA AURORA

Client: Crosswind (Shell & Eneco joint venture)
Location: Hollandse Kust Noord, the Netherlands, 22 kilometers
Distance from shore: 22 km offshore IJmuiden
Expected commissioning: 2025
Installed capacity: 0.5 MW
Surface area: 1 hectare
Water depth: 25m

After contract award in 2023, the project started with an extensive technical review. The engineering- and project management teams of Oceans of Energy learned how to document and report towards the high standards that companies like Shell and Eneco demand.

Oceans of Energy moved to a new facility for the purpose to support large-scale energy projects. Procurement and fabrication for the HKN1 project commenced in 2024 and by the third quarter of that year, regular shipments of the floating farm components went underway to the Port of  Amsterdam in preparation for the port deployment and offshore installation.

Covering a new area at sea with our state of the art energy system

The HKN1 offshore solar system brings together advanced marine engineering, lightweight modularity, and proven survivability in high wave environments. Designed for scalability and ease of deployment, the system floats effortlessly between the wind turbines of the Hollandse Kust Noord wind farm, creating a hybrid energy solution that makes smarter use of existing offshore infrastructure.

“Crosswind is excited to see this milestone reached through the collaborative efforts of NKT and Oceans of Energy. With the delivery of the dynamic subsea power export cable, we’re ready to connect for the first time in the world an offshore solar farm into the infrastructure of an offshore wind farm.” – Jeroen van Loon, Floating Solar Lead, Crosswind

A successfull permit application was achieved and contracting for the EPCI phase started. The dynamic subsea power export cable, which will connect the offshore solar farm to the nearest wind turbine foundation, was successfully tested and delivered. after which the cable was transported to site.

Ecological research

From the earliest stages of the HKN1 project, sustainability has been a guiding principle. Together with NIOZ and Rijkswaterstaat, we carried out an extensive environmental baseline study to understand the marine ecosystem before any offshore activity began. Using multibeam sonar, we mapped the seabed in detail, took sediment samples through box coring, and collected water for eDNA analysis to assess biodiversity. This research ensures we are not just building at sea, but building responsibly, with a full understanding of the environment in which we operate.The design of the floating solar system itself reflects this commitment. The layout of our floaters includes intentional spacing between the panels, allowing sunlight to reach the water below. This seemingly small design choice plays a critical role in supporting photosynthetic marine life such as phytoplankton and seaweed, key to the ocean’s ecosystem.Additionally, our system offers a form of interaction with nature. Some floaters are intentionally left panel-free, creating open, undisturbed spaces. These have already been observed as resting spots for seals, a small but meaningful sign that marine life is adapting to and coexisting with our technology.Oceans of Energy has also taken care in the materials we use. The entire system avoids anti-fouling coatings, which are commonly used in marine industries but often harmful to marine organisms. Instead, we apply only non-toxic, eco-safe paints and rust protectants. Most of the floaters themselves are made from recycled materials, closing the loop and supporting a circular economy.

Ecological Research

From the earliest stages of the HKN1 project, sustainability has been a guiding principle. Together with NIOZ and Rijkswaterstaat, we carried out an extensive environmental baseline study to understand the marine ecosystem before any offshore activity began. Using multibeam sonar, we mapped the seabed in detail, took sediment samples through box coring, and collected water for eDNA analysis to assess biodiversity. This research ensures we are not just building at sea, but building responsibly, with a full understanding of the environment in which we operate.

The design of the floating solar system itself reflects this commitment. The layout of our floaters includes intentional spacing between the panels, allowing sunlight to reach the water below. This seemingly small design choice plays a critical role in supporting photosynthetic marine life such as phytoplankton and seaweed, key to the ocean’s ecosystem.

Additionally, our system offers a form of interaction with nature. Some floaters are intentionally left panel-free, creating open, undisturbed spaces. These have already been observed as resting spots for seals, a small but meaningful sign that marine life is adapting to and coexisting with our technology.

Oceans of Energy has also taken care in the materials we use. The entire system avoids anti-fouling coatings, which are commonly used in marine industries but often harmful to marine organisms. Instead, we apply only non-toxic, eco-safe paints and rust protectants. Most of the floaters themselves are made from recycled materials, closing the loop and supporting a circular economy.

Inauguration & Christening (June 2025, Port of Amsterdam)

Nymphaea Aurora was inaugurated and christened in the Port of Amsterdam, marking readiness to move from port commissioning to offshore installation at Hollandse Kust Noord. Final port acceptance and pre-departure commissioning were completed successfully, with no faults detected—including in the electrical connectors. The farm was then cleared for tow-out via the Noordzeesluis (IJmuiden) to its position 18.5 km offshore within the wind farm.

Offshore Solar + Wind: A First-Of-Its-Kind Partnership

The HKN1 offshore solar farm is more than a technical achievement. It is the result of a fruitful collaboration between Oceans of Energy, Crosswind and many other key stakeholders. Together, we are demonstrating how two renewable energy technologies can be integrated to maximize positive impact as a key enabler for the industry and future projects.

“We are very pleased that Crosswind and their shareholders Shell and Eneco have trust in Oceans of Energy for realizing this first off amazing project. Our performance and our system will be key for the success of the innovational part of the offshore wind farm. This is a large responsibility as Hollandse Kust Noord will function as an example for combined offshore wind and solar parks in the future.” Allard van Hoeken – founder and CEO of Oceans of Energy

By combining floating solar with offshore wind, we are addressing one of the key challenges of renewable energy: intermittency. Solar energy can complement wind by generating electricity during sunny but low-wind conditions, smoothing out production profiles and increasing the overall utilization of the offshore grid infrastructure. This hybrid model helps stabilize renewable energy output and improves the efficiency through sharing offshore infrastructure.

Over the summer of 2025, offshore installation is executed, the first step being the installation of the permanent mooring system within the wind farm in April/May 2025.

Offshore Solar + Wind: A First-Of-Its-Kind Partnership

The HKN1 offshore solar farm is more than a technical achievement. It is the result of a fruitful collaboration between Oceans of Energy, Crosswind and many other key stakeholders. Together, we are demonstrating how two renewable energy technologies can be integrated to maximize positive impact as a key enabler for the industry and future projects.

“We are very pleased that Crosswind and their shareholders Shell and Eneco have trust in Oceans of Energy for realizing this first off amazing project. Our performance and our system will be key for the success of the innovational part of the offshore wind farm. This is a large responsibility as Hollandse Kust Noord will function as an example for combined offshore wind and solar parks in the future.” Allard van Hoeken – founder and CEO of Oceans of Energy

By combining floating solar with offshore wind, we are addressing one of the key challenges of renewable energy: intermittency. Solar energy can complement wind by generating electricity during sunny but low-wind conditions, smoothing out production profiles and increasing the overall utilization of the offshore grid infrastructure. This hybrid model helps stabilize renewable energy output and improves the efficiency through sharing offshore infrastructure.

Over the summer of 2025, offshore installation is executed, the first step being the installation of the permanent mooring system within the wind farm in April/May 2025.

Tow-out & Offshore Installation (August 2025)

Following final port acceptance, Nymphaea Aurora was towed from the Port of Amsterdam, passed the Noordzeesluis (IJmuiden), and reached its position 18.5 km offshore at Hollandse Kust Noord. Offshore works proceeded as planned and were completed safely.

What was installed offshore

  • Mooring / anchoring system: Hook-up and station-keeping verified.

  • Dynamic power export cable: Laid and connected to the nearest wind turbine monopile.

  • Mechanical scope: Tow-out, anchor handling, and cable operations executed as designed.

Operational at-sea performance highlights

  • Mooring hook-up completed; station-keeping verified at site.
  • Dynamic export cable: factory acceptance tested, delivered, and installed offshore.
  • Wave-following behavior: floaters and modules move with the sea as designed.
  • Weather events: The system has withstood named storms and strong winds (e.g., Storm Amy; wind force up to 9 Bft, Hmax ≈ 6.84 m) during the observation period.

  • Commissioning: July test operations functioned as intended prior to offshore installation.

Learnings

The operational period gave a wealth of learnings. These will be updated in this page.

Offshore Solar project afgerond

In de zomer van 2025 hebben Oceans of Energy en CrossWind een groot drijvend offshore solar systeem geïnstalleerd in windpark Hollandse Kust Noord. Het systeem met circa 1.400 zonnepanelen was onderdeel van de innovatieprojecten die CrossWind uitvoerde in het windpark om te onderzoeken of er ook stroomlevering mogelijk is wanneer er tijdelijk geen wind is. Hiermee draagt CrossWind bij aan de beleidsdoelstellingen van de overheid als het gaat om multifunctioneel ruimtegebruik van de Noordzee.

Aan de installatie ging een intensieve ontwikkel- en voorbereidingsfase vooraf. In de lente van 2025 werd het systeem uitvoerig getest in de haven van IJmuiden. In augustus werd het systeem naar zee gebracht en is daar succesvol geïnstalleerd binnen het windpark.

Kort na de installatie vonden er helaas thermische incidenten plaats op het offshore solar systeem. In de ontwikkelfase is, naast een eerder gekozen en geteste stekker, een tweede type stekker toegepast. Deze leek aan de vereiste specificaties te voldoen, maar uit nader onderzoek is gebleken dat er sprake was van een productiefout in de stekker, wat heeft geleid tot de thermische incidenten en de daaropvolgende beslissing om het systeem terug te brengen naar de haven van IJmuiden.

Waardevolle kennis en inzichten
Gedurende het project is veel kennis en ervaring opgedaan op het gebied van samenwerking, ontwerpkeuzes, kwaliteit en risicobeheersing bij innovatieve offshore‑projecten. Oceans of Energy en CrossWind sluiten dit innovatieproject nu af en delen de waardevolle inzichten met anderen voor toekomstige offshore solarprojecten.

Offshore Solar Project Completed

In the summer of 2025, Oceans of Energy and CrossWind installed a large floating offshore solar system in the Hollandse Kust Noord wind farm. The system, consisting of approximately 1,400 solar panels, was one of CrossWind’s innovation projects at the wind farm, aimed at exploring whether power generation is also possible during periods with little or no wind. In doing so, CrossWind contributes to the government’s policy objectives for the multifunctional use of space in the North Sea.

The floating solar system was installed following an intensive development and preparation phase. In the spring of 2025, the system was extensively tested in the port of IJmuiden. In August, it was transported offshore and successfully installed within the wind farm.

Shortly after installation, thermal incidents unfortunately occurred on the offshore solar system. During the development phase, in addition to an electrical connector that had already been selected and tested, a second type of electrical connector was used. While this connector appeared to meet the required specifications, further investigation revealed a manufacturing defect. This defect led to the thermal incidents and the subsequent decision to return the system to the port of IJmuiden.

Valuable Knowledge and Insights
Throughout the project, valuable knowledge and experience were gained in the areas of collaboration, design choices, quality, and risk management in innovative offshore projects. Oceans of Energy and CrossWind have now concluded this innovation project and will share the insights gained with others to support future offshore solar projects.

The development of Nymphaea Aurora has received funding from the European Union’s Horizon Europe research and innovation programme under the project BAMBOO, Grant Agreement number 101136142.Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Climate, Infrastructure and Environment Executive Agency (CINEA). Neither the European Union nor the granting authority can be held responsible for them.

Interested in working with us?

HKN1 is the first of many offshore solar projects we aim to realize. As we continue to scale this technology globally, we welcome new collaborations with partners, developers, and innovators in the offshore energy space.

If you are interested in learning more about our systems or exploring project opportunities, feel free to reach out.