Competing with the sun

Back in 2013, Climate-KIC published its very first case study on Eternal Sun. Fast-forward to 2015, with a recent move to a larger premise and a new head office in The Hague (NL), we revisited Eternal Sun on a one-on-one with its CEO and co-founder Chokri Mousaoui for an update.

Eternal Sun

Eternal Sun is a high-tech company specializing in solar testing equipment for the purpose of product and material testing. Their solar simulators are innovative, reliable and practical in use and are sought out by customers worldwide. Events which aided and led to Eternal Sun securing its first major financial investment (€2 million, Series A financing), and how they are using this sizeable financial injection for an interesting story.

Eternal Sun was founded in 2011 during a research project at Delft University of Technology (TU Delft). Founders, Chokri Mousaoui and Stefan Roest conducted a combined project on solar panels and soon found themselves in need of an accurate solar panel testing equipment. Having realized that such a solution did not exist, they quickly identified their niche and shortly after decided to start their own company. Eternal Sun’s inception came about, with the goal of providing accurate sunlight simulation equipment enabling customers to test their solar panels under virtually any condition, replicating actual sunlight ranging from the UV spectrum all the way into the Infrareds, and any angle imaginable. What made them unique is that their solution does this, packaged within a practical and compact design, removing the need for large testing facilities costing multiple millions of euros.

During its startup phase, Eternal Sun was taken under the wing of Climate-KIC partner and startup incubator Yes!Delft, providing them with excellent facilities and offering them the necessary support to turn their venture into a success. Engaging with co-startups, entering in startup competitions and joining in on events organized at the incubator significantly helped Eternal Sun get the traction it needed to move forward.

Chokri Mousaoui – CEO and co-founder of Eternal Sun, identified the two reasons behind their success as a combination of having an early prototype – an unappealing box-shaped system – and having a remedy to their customer’s pains. The combination resulted in a first transaction to launching and validating customer TNO back in 2011. Their system shaped ‘artificial sun’ got their idea across and held the interest of a TNO researcher long enough to talk business and close a deal, kick-starting their global endeavor.

Eternal Sun & Climate-KIC

So how did Eternal Sun and Climate-KIC meet? The first contact was established at a regular lunch at Yes!Delft, where Dutch Entrepreneurship Lead Frans Nauta and Chokri Mousaoui started talking. One thing led to another and Eternal Sun applied for and was accepted to Climate-KIC’s Acceleration Program; gaining access to expert coaching, international master classes, the USA startup tour, Climate-KIC’s venture competition (which they won), and a welcome €75.000 grant funding (for stages 2 & 3) that comes with it.

Chokri’s entrepreneurial spirit is perhaps best demonstrated by his decision in joining the USA Startup tour one week before his wedding; literally arriving back home from the USA a day prior to making the walk down the aisle. He casually mentions the reason behind his decision to go: “I told myself that an easy solution would be to say ‘no’, however easy solutions are often not the path towards entrepreneurial success; and if I would let a massive opportunity like this one go to waste, I will never become a successful entrepreneur.” His wife and he are happily married to this very day.

Eternal Sun has come a long way since landing its first deal. Soon after its initial sale, other interested parties and solar panel manufacturers approached them. Eternal Sun made its first cross-ocean endeavor and sold its products on a global scale, with orders flying in from Asia, EMEA and Americas. Activities continued to expand and Eternal Sun achieved the milestone of having a customer on every continent before the end of 2014. Eternal Sun is –literally- in every corner of the world, with sales reaching a peak of 40 unique orders in the past two years.

Current Developments

The €2 million external investment attracted in December 2014 enabled Eternal Sun to move into a larger premise at the beginning of March 2015, ramping up production and further expanding global activities. The move reflects the strong performance Eternal Sun has shown over the years; and with its ‘family’ expanding from two, to three (2011), to eight (2013), and now twenty (2015) full-time employees, business is in a rush. Such an expansion is usually coupled with new challenges and when asked about how to deal with new management topics such as: marketing, people management and operations, Eternal Sun keeps things ‘simple’. The rules: new employees should have three qualities:
1. Be skillful, know your field; 2. Be fun, communicate and socialize and 3. – most importantly – get stuff done.

Lessons Learned Moving Into the Future

When asked about lessons learned as a startup, Chokri highlights the importance of joining and competing in as many startup competitions you physically can: “just to get you over that detrimental stage fright that limits the strength of your idea.” If you don’t have a good story to back-up your idea, you are not going to convince anyone else. In addition, competitions bring out your strengths, but more importantly your weaknesses; they tell you what is wrong with your idea and put you back in your place.

“Who knows, you just might find yourself right at the very heart of Silicon Valley holding the next CleanTech Global Ideas Award, thanking the audience with an eternal sun smile.”

– Chokri Mousaoui (CEO)


For more information visit the website or contact:

Eternal Sun
Chokri Mousaoui (CEO)
Stefan Roest (CTO)

Wolga 11
2491 BK, the Hague
The Netherlands

Phone: +31 15 744 0161