Amsterdam’s Bolster Investment Partners acquires 80% stake in the Hague-based Eternal Sun

The Hague-based Eternal Sun, a company specialising in solar panel testing technology, has announced that Amsterdam’s Bolster Investment Partners has acquired an 80 per cent stake in the company. 

The shares were previously held by Vermec and ABN AMRO Sustainable Impact Fund, who supported the company during its early and expansion phases. 

With this transaction, Eternal Sun aims to continue growth, develop technology, and advance internal operations.

Advanced solar panel testing technology

Eternal Sun provides solar panel testing technology to manufacturers, laboratories, and developers in more than 60 countries. The company operates from six locations across four countries and offers simulators and inspection services.

Stefan Roest, after leading the winning Nuna Solar Car Team of TU Delft in 2007, founded Eternal Sun in 2011. The company has since expanded into a global provider of solar testing equipment.

Stefan Roest says, “Our technology is essential for accurately determining the performance and thus value of solar panels, which plays a critical role in the development and scaling of next-generation technologies such as tandems and perovskite.”

Eternal Sun also provides flash and steady-state solar simulators, along with inspection services for importers and solar project developers. Roest adds, “Thanks to our deep expertise, flexibility, and focus on customisation, we continue to lead in a rapidly evolving market.”

Scaling with vision

CEO at Eternal Sun, Florian van Rijn van Alkemade, says, “We grew as a scale-up, and now we welcome an investor focused on scaling mid-sized companies. We are very proud of our continuous and uninterrupted growth track in what have sometimes been difficult market conditions.”

“It provides proof of how we’ve strategically diversified our business in recent years. It is also a great tribute to our team, we could not have reached these milestones without their continued enthusiasm and drive.”

CCO Erik Bentschap Knook adds, “We’re playing in the solar industry’s Champions League. Our clients are the most advanced PV developers in the world. We work with them to enable a fast to new technologies like tandem and perovskite, we see a bright future for Eternal Sun.”

Partnership with Bolster

Founded in 2017, Bolster Investment Partners is a long-term investor that focuses on successful Dutch companies with proven business models. It partners with entrepreneurs to help them reach their full potential through equal and strategic collaboration. 

This partnership with Bolster represents a key milestone for Eternal Sun. In addition to providing capital, Bolster offers strategic guidance to help drive the company’s buy-and-build strategy, expand internationally, and improve its operations.

Mark van Rijn, Managing Partner at Bolster, says, “The global leadership position of Eternal Sun, combined with its innovation capabilities, creates a unique position. The solar testing market is growing rapidly, driven by new technologies and energy independence trends. Eternal Sun is exceptionally well-positioned, and we look forward to working with their strong and visionary team.”

Successful exit for ABN AMRO

ABN AMRO Sustainable Impact Fund (ABN AMRO SIF) has exited its investment in Eternal Sun, transferring majority ownership to Bolster Investment Partners.

The ABN AMRO SIF is one of the largest private impact funds in the Netherlands, investing in companies that benefit the environment, climate, or society. With €500M in funding, the fund focuses on direct equity investments in sectors such as energy transition, the built environment, and sustainable consumption.

ABN AMRO SIF’s investment and exit exemplified its goal of achieving both financial return and environmental impact, as Eternal Sun’s technology helps improve solar panel performance and consistency, contributing to higher global solar output.

In 2019, ABN AMRO SIF partnered with early investor Vermec to support Eternal Sun, based on confidence in the expanding global solar PV market. According to a statement from ABN AMRO, the market has since grown by over 20 per cent annually, increasing the need for testing solutions. 

Eternal Sun took advantage of this growth, with support from ABN AMRO SIF and Vermec, by acquiring Spire Solar (USA) and SunChine (China), while also expanding its business and operations internationally.

Florian van Rijn van Alkemade, CEO of Eternal Sun, says, “ABN AMRO SIF was a true growth enabler for Eternal Sun, challenging us to think bigger and providing the capital to focus. As we scaled, they remained a valuable sounding board for our organisation and stood by us in good and challenging times. We’re grateful for their contribution to our journey.”

Thijs Nijland, Investment manager of ABN AMRO SIF, adds, “We are proud to have supported the company and its highly committed management team through a pivotal growth phase, and to have witnessed its transition from startup to a well-established global market leader.”