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How Does a Solar Refrigerator Work?

How Does a Solar Refrigerator Work

As more and more household appliances make the switch to solar power, it has become clearer that renewable energy is the future. From solar furnaces to solar refrigerators and freezers, everyday devices are starting to go green. Lately, solar refrigerators have joined the list of eco-friendly, solar-powered appliances that drastically reduce energy consumption.

Solar refrigerators were once reserved for in-field military operations and emergency medical centers. However, in recent years they have caught on among everyday consumers looking for creative new ways to make their kitchens more environmentally sustainable.

Since solar refrigeration is a relatively new technology, very few people understand how these devices work and why they are so important. To help you better understand solar refrigeration and the benefits that these innovative fridges offer, we put together this quick guide.

A Solar Fridge? But Why?!

There are many reasons why solar refrigerators have the edge over regular refrigerators. For one, greater energy efficiency allows solar refrigerator owners to save money on their power bills every month. Unlike regular fridges, solar refrigerators run on DC electrical current which does not require a wasteful AC converter.

Second, solar fridges are completely free to use. This is because solar refrigeration uses photovoltaic cells to produce more energy than the fridge consumes. As a result, solar fridges have a “net negative” energy status. Not only is this more environmentally sustainable, but it also means you will save on your utility expenses.

A Solar Fridge But WhyLast, solar power is generally safer than most other forms of energy production, especially non-renewable energy. Whereas conventional appliances rely on an electrical grid powered by hazardous coal, nuclear, or natural gas, solar energy leaves zero waste when generating power. Likewise, they are safer during installation since they don’t require any tampering with your house’s electrical system.

How They Work: A Point-by-Point Guide

“How does a solar refrigerator work?” This is a question we are asked on a routine basis. As the price of solar refrigeration continues to nosedive, more and more of our readers have inquired about this cool new technology. Below, we break down how solar refrigeration works in the simplest terms possible.

Turning Hot to Cold

In a nutshell, solar refrigerators take something naturally hot, sunlight, and convert it into energy to chill its storage compartment. It has no moving parts, and it requires no electrical source—all it takes is plain old sunshine.

Unlike the commercial refrigerator in your kitchen, which uses a motor to compress a refrigerant solution, solar fridges are “absorptive.” An absorptive device, such as a solar fridge, will take a source of heat, like sunlight, and use the thermal energy to convert the refrigerant solution into liquid. As a result, energy is produced, and the fridge can sustain itself and the contents within it.

Refrigerants 101

There are many common refrigerant solutions found in solar refrigerators and electric refrigerators alike. One of the most common solutions is a mixture of water and ammonia or sometimes water and lithium bromide. Together, these substances create a vapor or liquid refrigerant which is used inside all modern refrigerators.

Handling any kind of refrigerant should be careful exercise. Since many refrigerants have potentially harmful effects when consumed, it is critical that you always store them in safe places and proceed with caution whenever you supply your fridge with them. For more information about refrigerant safety, check out the National Refrigerants, Inc. website.

Cooling the Refrigerant

To chill the contents of the fridge, the coolant (or refrigerant) needs to be converted from vapor to liquid (or vice versa). This is because the conversion process creates thermal energy, which can then be used to power the DC electrical systems found inside the solar refrigerator.

At the start, solar refrigerators are supplied with refrigerants in a gaseous form. However, once heated is supplied via exposure to the sun, more pressure is placed on the gases until they eventually condense into a liquid. When removed from the heat source, the liquid depressurizes and reverts back to its original gas form.

Efficiency

Most commercial solar refrigerators create between 65 and 75 Btus (British thermal units) of cooling power after absorbing roughly 100 Btus of heat via sun exposure. This means solar refrigerators are energy efficient, as most of the energy consumed is used to produce their cooling effects.

Insulation

To keep cool for hours, solar-powered refrigerators rely on heavy insulation around its lining. Insulating substances, usually in the form of metals or foams, shield the contents of the refrigerator from external heat. In other words, they let the food and other items inside the fridge stay nice and cool even when the device is left out in the sun.

Without insulation, a fridge is useless. Insulation is laid throughout the bottom, top, and sides of the fridge so the internal temperature of the fridge remains constantly over several hours—even without sunshine or an external energy source. Try finding a commercial refrigerator that can do that!

No Battery, No Problem

In the early days of solar refrigeration, solar fridges used sunshine and PV cells to charge lithium-ion batteries. These batteries could maintain a charge long enough to supply the fridge with energy for several hours at night or in the absence of sunlight. However, by the 1990s this system was replaced by a new one designed by NASA.

These days, solar refrigerators feature no battery at all. Instead, the change of the refrigerants phase from gas to liquid produces enough thermal energy to keep the fridge going without a source of sunshine. This way, no batteries are required to power solar refrigerators at night. Pretty convenient, aren’t they?

Buyer’s Guide

Are you in the market for a solar refrigerator? Here is a quick guide to help you make the best purchasing decision. By following these guidelines, you can rest assured knowing you made a responsible purchase while minimizing the risk that comes with shopping for nascent technologies:

  • Look for solar refrigerators that contain safer refrigerant substances like bromide
  • “Phase change” solar fridges are more energy efficient than battery-powered ones
  • Make sure all sides of the fridge are well-insulated and not leaking heat
  • For some of the most trusted solar refrigerators on the market, check out the Ben’s Discount Supply website