Refrigeration & Solar Systems - How To Minimise Consumption

Refrigeration accounts for a very significant part of domestic energy consumption. This is especially true for households living off-grid who generally have less electrical appliances, making refrigeration an even bigger part of their overall daily electricity usage. Fortunately, the efficiency of refrigeration systems has significantly improved over the years, making them much better suited to operate on solar systems, particularly in off-grid situations.

Star label ratings

Prioritising energy efficiency is essential when selecting a new refrigerator or freezer. Star labels offer consumers a standardised measure of energy efficiency, with higher star ratings indicating greater efficiency and lower energy consumption. However, it is important to remember that actual energy consumption varies greatly based on usage patterns and environmental conditions.

Here are some simple strategies to minimise the energy consumption of refrigerators:

  1. Set the Temperature Correctly: Refrigerators are designed to operate most efficiently within a specific temperature range. Aim for the top of that range for optimal efficiency, minimum energy usage and food safety, usually 5°C for the main compartment and -18°C for the freezer.
  2. Keep the Fridge Full: A full fridge retains cold better than an empty one, as the mass of cold items helps to stabilise temperature fluctuations when the door is opened. If your fridge is not full, you can fill empty space with containers of water.
  3. Defrost the freezer: Make sure to regularly defrost the freezer, as excessive ice buildup reduces its efficiency.
  4. Check the door seals: Keep seals clean and free from damage to prevent cold air from escaping.
  5. Keep the fridge clean and well ventilated: Dust and debris can accumulate and reduce the fridge efficiency. Clean the coils and vents to ensure optimal airflow, and ensure there is sufficient space around the fridge for proper ventilation.
  6. Avoid placing hot food inside the fridge: Allow cooked food to cool to room temperature before placing it in the fridge, as hot items make the compressor work harder to maintain the desired temperature.
  7. Organise the fridge efficiently: Arrange fridge items to maximise airflow and ease of access to reduce how long the door stays open.
  8. Consider the room temperature: Keep the fridge away from heat sources such as ovens, dishwashers, or direct sunlight.
  9. Use Energy-Saving Features if available: Some modern fridges have energy-saving features such as vacation or eco modes. Activate these features when appropriate to further reduce energy consumption.

12/24V DC fridges and freezers

Most refrigeration systems operate on alternating current (AC) and have become a lot more efficient over the past decades, making them suitable for a wide range of solar systems.
However, direct current (DC) refrigeration systems are still relevant and especially well-suited for small 12V or 24V off-grid solar systems as they do not use power from the inverter which is limited in size on such systems, while minimising energy losses and improving overall efficiency. Note that they are usually chest fridges, as opposed to upright fridges, which may be less convenient due to stacked items.

Gas fridges and freezers

Gas-powered refrigerators and freezers utilise propane or natural gas as a refrigerant, providing reliable cooling without electricity and offer a viable off-grid alternative, particularly in areas with limited solar exposure.

For more information, refer to the Energy Rating Website: