More Than Just Solar

When you look at a Sunswap-powered refrigerated trailer, the solar panels might catch your eye first.

"So you put solar panels on trailers?" It's an understandable question, but it’s far from the truth.

Five years ago, our engineering team didn't set out with solar panels in mind at all. We started with a much more fundamental question: how do we make a diesel refrigeration system electric without compromising on performance? (A rather ambitious challenge, if we're being honest).

While solar power has become a critical piece of the technology mix, Sunswap Endurance is first and foremost a purpose-built electric transport refrigeration unit. The story begins well before those panels ever entered the picture.

Electrifying Transport Refrigeration

Going from diesel refrigeration to an electric system was anything but straightforward. Our engineering journey began with first principles, building a refrigeration system that maximises efficiency and ensures that every kilowatt of energy is used optimally.

This meant questioning everything we thought we knew about refrigeration and re-examining every component from the ground up:

• We replaced diesel engines with high-efficiency electric motors
• We redesigned heat exchangers and cooling systems specifically for electric operation
• We developed advanced control systems to optimise performance across varying conditions
• We built a system with fewer moving parts to enhance reliability and reduce maintenance

The result? A refrigeration unit that doesn't just match diesel performance but improves upon it in key areas like temperature control, noise levels, and maintenance requirements.

And that's when the real magic happened.

Batteries at the Core

With an efficient refrigeration system designed, the next question was power. How do you reliably run an electric refrigeration unit through long delivery cycles, changing conditions, and varying demands?

The answer came in the form of a modular battery system - the true foundation of Endurance's capabilities. This system provides reliable, consistent performance while offering something diesel cannot: customising for different operational needs.

Our modular battery approach means:

• Operations with shorter routes can optimise for weight and cost with fewer battery modules
• Long-distance or multi-day operations can add capacity for extended runtime
• Mixed operations can find that sweet spot balancing range, weight, and performance

Powering a Fridge

With our core electric system established, we faced a critical question: how could we extend the range without compromising the benefits we'd worked so hard to create?

We evaluated several approaches, each with their own drawbacks:

• Regenerative axles offered energy recovery during braking but added weight and complexity, only generating power during specific driving conditions
• Power take-off (PTO) systems would draw energy from the tractor unit, compromising the truck's own range (no good for a future where trucks are electric) and creating complex integration requirements
• Simply adding more batteries would increase weight and cost without addressing fundamental efficiency challenges

Each option seemed to solve one problem while creating others. We needed something better.

Enter Solar Panels

This is where solar power finally entered our design considerations, not as the primary energy source, but as the perfect add-on to our battery system.

Our initial tests highlighted the really exciting potential for solar.

Transport refrigeration faces its greatest energy demands during hot weather - precisely when solar generation is at its peak. This creates a perfect relationship between energy need and energy production that we hadn't fully anticipated.

In summer months, traditionally the most challenging for refrigeration, our solar panels can provide up to 98% of the energy required for chilled operations. This turns what would be the most demanding scenario for a diesel unit into a highly sustainable operation for Endurance.

Real-World Validation

Engineering theories are wonderful, but real-world performance is what truly matters. Our extensive trials across diverse operations have demonstrated the system's capability to maintain stable temperatures across all types of routes and deliveries.

As our customer base has expanded to include major operators like DFDS, Samworth Brothers, Bannister Transport, and Cranswick, this performance reliability has been validated across different sectors and operating environments.

The solar panels on our trailers may be the most visible sign of innovation, but they represent just one element in a carefully engineered system designed to transform refrigerated transport.

After all, we're not just a solar company. We're engineers and we are a manufacturer, solving one of transport's coldest challenges from the ground up.