On the day a Dutch bank was set to give final approval for financing, the US president unexpectedly announced new import tariffs: 125% on Chinese goods, 20% on European goods. The bank withdrew. For Bolster, Eternal Sun and advisor Oaklins, that meant a severe test in an already complex sale process.
In May 2025, Bolster Investment Partners acquired a majority stake in Eternal Sun, the global market leader in testing equipment (solar simulators) for solar panels. Erik Bentschap Knook, co-owner and CCO of Eternal Sun, sees plenty of room for growth in his market: “The huge global increase in demand for electricity and electrification calls for a substantial contribution from solar energy. That’s going to play an important role, not least because of pricing: the cost of solar energy has dropped sharply, making it highly competitive worldwide.”
It was precisely in that growth market that a long and layered sale process unfolded. In early 2024, Eternal Sun’s shareholders decided to look for a partner and selected Oaklins Netherlands as exclusive advisor. After the summer, more than twenty management meetings followed, narrowing the field to two preferred parties – including Bolster.
Two nearly simultaneous deals
The transaction became more complex because Bolster and Eternal Sun were also preparing, in parallel, the acquisition of Germany’s Wavelabs, a manufacturer of simulators for measuring solar cells. The two deals were closely intertwined: the success of one depended on the success of the other. When the tariff announcement caused the previously agreed financing to collapse, Bolster, Oaklins and the selling parties worked together to find a solution that allowed the deal to proceed after all. Both acquisitions closed in May 2025; in December of that year, the transaction won the M&A Award for Best Small-Cap Deal.
Tom Snijckers, partner at Oaklins Netherlands, sees that ability to stay the course as decisive: “In a complex sale process like this, entrepreneurs need to keep their eyes on the horizon. Things keep changing, but you have to stay level-headed and push through.”
A year on
The numbers bear the shareholders out. Wavelabs now sells its products through Eternal Sun’s US sales network and has gained greater market access in Germany and India. The company is outperforming the targets set out in the 2027 investment memorandum and has further professionalized with a new CEO, COO and CFO.
Mark van Rijn, co-founder and managing partner at Bolster, points to the quality of the collaboration as the explanation: “It’s still early days, but the collaboration with Eternal Sun is fantastic – open and transparent. That lets us add value to the company while getting the information we need in return. We’re very pleased with how it’s developing.”
Equal partners
The Eternal Sun deal shows how Bolster works with entrepreneurs as an equal partner, even when circumstances change along the way. An acquisition rarely goes exactly as planned. The ability to adapt quickly together with the selling party and advisors, without losing sight of the underlying deal or the mutual trust, determines whether a complex process still leads to a good outcome.
The full article was published on Oaklins’ international website on 23 July 2026.
Read it here: Tariffs, Parallel Deals and Market Challenges
