German Field Trial Shows Solar Cold Storage Held -18°C For More Than Seven Days

German Field Trial Shows Solar Cold Storage Held -18°C for More Than Seven Days

Germany - August 2026 - A field trial in Germany has demonstrated that a solar-powered refrigerated container can maintain a -18°C temperature setpoint for more than seven days without a connection to the electrical grid, according to Trane. The test was carried out under predominantly cloudy conditions and was designed to evaluate the performance of an autonomous cold-storage system for off-grid applications.

 

The trial is notable because maintaining stable temperatures for frozen products requires continuous refrigeration, even when solar generation changes throughout the day. Instead of relying on grid electricity, the tested system combined photovoltaic power generation with battery storage and a highly insulated refrigerated container.

A Solar-Powered Refrigeration System Tested In Germany

The system tested by Trane used a 20-foot C-Store PLUS refrigerated container with high thermal insulation. An integrated solar frame with photovoltaic panels supplied electricity to the system, while a dedicated DC transformer and battery energy storage system were used as part of the power setup.

 

During the field trial, the container operated continuously with a -18°C setpoint, while outdoor temperatures ranged from approximately 20°C to 30°C.

 

Solar power input varied according to weather conditions. Trane reported approximately 0.5 kW during rainy conditions and up to 4.5 kW under sunny conditions. The system therefore had to operate with changing solar availability rather than relying on a constant power source.

 

Battery Storage Supported Operation During Limited Sunshine

Battery storage was another important part of the test.

 

The system used a 35 kWh backup battery pack, which Trane reported remained almost fully charged throughout the trial. According to the company, the refrigerated container remained autonomous for the duration of the test despite the limited sunshine and predominantly cloudy weather.

 

The results also provide an example of how solar refrigeration systems can combine different energy sources within one setup. Solar panels supply power when solar energy is available, while battery storage provides an additional energy buffer when generation changes.

 

This type of configuration can be particularly relevant to cold-storage applications where reliable electricity is not always available.

 

Insulation Plays A Key Role In Cold Storage

The trial also illustrates why refrigeration performance cannot be considered separately from the thermal design of a cold-storage system.

 

Maintaining a frozen temperature requires the refrigeration system to continuously remove heat entering the storage space. Better insulation can reduce that heat load and, as a result, reduce the amount of energy required to maintain the target temperature.

 

In the Trane trial, the refrigerated container used an ultra-insulated design. The combination of thermal insulation, solar generation and battery storage allowed the system to maintain the -18°C setpoint throughout the reported test period.

 

It is also important to note that this was a specific field test of a particular refrigerated-container configuration. The results should not be interpreted as meaning that every solar freezer or solar cold-storage system can automatically operate for seven days without grid electricity. Performance will depend on factors such as refrigeration load, insulation, solar availability, battery capacity, ambient temperature and system design.

 

What The Trial Means For Off-Grid Cold Storage

The German field trial comes at a time when refrigeration is increasingly being considered for locations where grid electricity is limited, unreliable or unavailable.

 

Cold storage is particularly sensitive to power interruptions because frozen food, pharmaceuticals and other temperature-sensitive products require controlled temperatures over extended periods. Solar generation combined with energy storage provides one possible approach for reducing dependence on conventional grid power.

 

Trane said the tested system is intended to respond to demand for flexible and lower-emission temporary cold-storage options, particularly at locations where access to electricity is restricted or unreliable. The company also offers the system through its rental services for short- and long-term applications.

 

The trial does not establish a universal operating standard for solar refrigeration. However, it provides a real-world example of how solar PV, battery storage, thermal insulation and refrigeration equipment can be integrated into an off-grid cold-storage system.

 

For the wider refrigeration industry, practical field tests such as this can provide useful information about how solar-powered cold storage performs when weather conditions and energy availability change.

 

For More Information

For a closer look at solar refrigeration applications and cold-storage equipment, see Edobo Solar Refrigeration Products.

 

Source

Trane, "Trane runs 7-day trial for solar-powered refrigerated container in Germany, delivering 24/7 operation at -18°C setpoint," August 5, 2026.