How do you go about installing 18,000 solar panels on the roof?

In new construction projects, solar panels have become an integral and almost automatic part. Even for existing buildings, there are now increasingly smarter solutions that offer more possibilities for sustainability. This is exactly what we are doing at The Green Box: gradually transforming a site with 18.5 hectares of land and 80,000m2 of existing offices, production halls, and testing locations into an intelligent, sustainable cleantech campus.

Working with locations that have existing tenants, high energy demands, and a significant amount of existing (often old) infrastructure brings its own set of challenges. In this series, we will guide you through our plans and share the most important lessons we have learned at each step. Like many other companies transitioning to sustainable energy, we began with the basics: generating our own clean power with solar panels.

Read on to discover more about sun-reflecting roofs, seamless collaboration, and the role of insurers in solar installations.

Step 1: Mapping the Grid Connection

The grid operator is one of the key stakeholders in this process. A significant challenge that grid operators are currently facing in many areas of the Netherlands is grid congestion. As a result, obtaining a proper connection or being allowed to feed energy back into the grid is no longer a given. A refusal from the grid operator can impact the feasibility of a solar roof and impose restrictions on additional installations if grid feed-in is not possible. Thankfully, there are still plenty of possibilities to implement a solar installation, even in areas with high grid congestion.

Step 2: Assembling the Project Team & Engaging Stakeholders

Our location in Hengelo used to be a typical industrial site in the Netherlands a few years ago. Now, it proudly hosts around 18,000 solar panels installed on the roofs of various buildings. However, achieving this feat was not a simple task, nor was it accomplished by a single individual.

To construct the solar roof and effectively manage the project, The Green Box chose to collaborate with the expertise of Koolen Energy Projects. The team brings substantial knowledge and experience in large-scale solar power projects, with a focus on other future systems such as charging stations and energy storage and management systems.

Mark Schat, General Manager at Koolen Energy Projects, explains, "The greatest challenge in establishing a solar roof is the involvement of numerous stakeholders. It requires effective communication and coordination with these parties. It is vital to engage the right stakeholders in the correct sequence. For example, initiating discussions with the insurer before requesting a quote for the appropriate solar panels."

Below, you will find a concise overview of the step-by-step plan outlining when we engaged each stakeholder in the process and the crucial information we needed from each party.

Step 3: Preparing the Roof

First and foremost, it is important to determine whether solar panels can be installed on the existing building and under what conditions. The weight of solar power systems adds an extra load to the roof, especially when they are weighted down with ballast.

"In the case of The Green Box, the roofs had limited load-bearing capacity. Instead of using ballast to add weight to the solar panels, we opted for anchoring the substructure to the roof structure," explains Mark.

By creating a ballast plan for the solar panel installation and having it assessed against the structural calculations of the roof, it can be determined if the roof is strong enough. Solar panels have a lifespan of up to 30 years, so it is crucial to properly prepare the roof to avoid any replacements being necessary in the interim.

Mark states, "Before installing the solar panels, the roofs were fully equipped with new insulation and new roofing material to ensure the roof remains in good condition for many years."

The Construction of the Solar Roof

Roofing specialist Erdo has outfitted an impressive 50,000 square meters of roof surface with new insulation and roofing material. White PVC was chosen for this purpose. This material reflects a significant amount of sunlight, resulting in reduced heat absorption by the buildings and the solar installation itself on sunny days. As a result, the need for cooling is diminished. Moreover, the reflection contributes to enhanced energy generation.

Step 4: Designing & Implementing the System

The Green Box is in a unique situation. The premises are equipped with their own 10 kV ring, which means that all the energy generated by the solar panels is directly fed into the 10 kV ring through the inverters. This allows the connected businesses at The Green Box to utilize the generated electricity as alternating current via their electrical meter.

"Typically, power is fed through distribution cabinets or existing transformers. However, due to limited capacity, the substantial power involved, and the indoor locations, we decided to purchase a new transformer and install it outside. This approach provides enhanced safety, which pleased our insurer," explains Mark Schat.

Feeding power indoors poses the risk of additional requirements from insurers. Managing insurers from different businesses can be complex and may result in additional costs and project delays.

After conducting thorough research, The Green Box selected DMEGC panels. Several factors, such as weight, handling, and performance, played a role in this decision. The solar panels on the roof of The Green Box are installed in a specific "wave" configuration.

"We typically install solar panels on flat roofs in an east-west orientation, which offers several advantages over a south-facing orientation. While south-facing panels generate the highest power output, they create a large peak in energy production, putting a significant strain on the grid. In contrast, the east-west orientation spreads out the energy production, resulting in a more balanced profile and reducing the need for grid constraint measures. It aligns energy generation more effectively with consumption. Moreover, this configuration allows for a higher density of panels on the same roof without requiring spacing between them. This increases the power output per square meter, enabling more energy production on the same roof."

This orientation has an additional benefit: it is less susceptible to wind, typically requiring less ballast or anchoring. Given the current load-bearing capacity of the roofs at The Green Box, this advantage is significant. Additionally, the reduced need for ballast or anchoring directly leads to lower installation costs.

The Result

The Green Box is extremely proud of its solar roof and delighted with the excellent project management provided by Koolen Energy Projects. Through smart control systems, The Green Box has achieved a high level of simultaneity, meaning that energy generation aligns closely with the energy demand at the site. The majority of the self-generated energy is utilized directly. Any excess energy is seamlessly supplied to the grid through the connection with Enexis, allowing others to benefit from this surplus power.

A Glimpse into the Future

We are actively working towards transforming The Green Box into Europe's most innovative cleantech campus. The solar roof is a key element in this transition, and we are incredibly proud of the results. Now that we have achieved a significant level of self-generation capacity, we are exploring options to become increasingly independent, smarter, and more sustainable in our energy practices.

"Our solar roof generates enough power to supply electricity to 1,900 households per year." And we are just getting started.

Currently, we are contemplating the best solutions for managing temporary energy overproduction. Do battery systems offer the most flexibility? Or is bidirectional charging the optimal answer? And how do the different business cases compare?

Follow us on LinkedIn to stay updated on these exciting developments in the near future!