Energy Storage

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Since solar energy comes from the sun, it means that it is not present during nighttime. This is why efficient energy storage systems are needed. Unlike conventional power sources that continuously flow through electric grids, solar energy needs to be kept within a system which can hold it without diminishing its strength. For this purpose, researchers and companies specializing in renewable energy concentrate on finding ways to minimize the production costs of high efficiency solar cells and to optimize the electrical efficiency of conventional solar cells.

Efficiency of solar energy

At present, high efficiency solar cells are more capable of storing and generating solar power compared with regular solar cells in terms of electrical output per incident energy. As for solar thermal plants, the famous Solar Two project on solar thermal energy in the United States Mojave Desert and in Spain has achieved 99% efficiency by using molten salts in its storage system.

How solar energy is stored

There are several types of solar energy storage systems. One type is the thermal mass system which can contain solar energy in the form of heat. Maintained at a local temperature, the stored heat is made available for both regular and seasonal use with the aid of high-heat capable materials, such as earth, stone, and water. Another type of solar energy storage uses phase change materials like Glauber’s salt and paraffin wax. These materials can carry and maintain domestically useful heat at 64 degrees Celsius. Molten salt may be used to maintain solar energy at high temperature. Aside from being inexpensive, the temperature in energy storage systems using molten salts can match that of a traditional power system. Another means of storing solar power is through off-grid (not connected to an electric grid) photovoltaic systems, which utilizes rechargeable battery cells to hold excess electricity. More studies are being done to enable photovoltaic panels to store energy without the use of batteries.