Mobile, clean energy from the Connectr Innovation Lab

Alongside Rift, another Challenger50 company from our Innovation Lab is in the spotlight: WATTSUN. In the new Sprout Challenger50, this Arnhem-based company is also among the most promising entrepreneurs in the Netherlands, recognition of their forward-looking approach to fully emission-free mobile energy.

Smart, stackable powerhouses

WATTSUN develops modular battery systems that can replace traditional diesel generators. The system consists of a powerful base unit that can easily be stacked with additional modules to add more power or capacity. This creates a flexible and scalable energy system that operates on construction sites, at events, in temporary installations, and at locations without a grid connection.

Unlike a generator, WATTSUN operates completely silently, cleanly, and emission-free, directly contributing to emission-free working and living environments.

Why Sprout selected them

WATTSUN is seen as a challenger because they show that temporary energy supply no longer needs to depend on polluting diesel. Their system is compact, intelligently designed, and quick to deploy—exactly the kind of disruption the market needs. Recognition in the Sprout Challenger50 confirms the relevance and scalability of their solution.

From Arnhem to the world

WATTSUN’s innovation takes shape in the Connectr Innovation Lab at Cleantech Park Arnhem. In collaboration with partners from the ecosystem, testing, further development, and scaling take place here.

This approach is working: WATTSUN’s battery systems are now used in more than fifty countries, ranging from European construction sites to off-grid applications worldwide.

A mission with lasting impact

WATTSUN’s goal is clear: to make clean, mobile energy available wherever it is needed. By replacing diesel generators with smart, silent, and emission-free battery systems, they contribute to a cleaner construction sector, more sustainable events, and a faster energy transition.

Their place in the Sprout Challenger50 shows how strongly innovations from the Arnhem ecosystem are developing.

Read the full story of WATTSUN via Sprout: Wattsun – Challenger50 of 2025.