Thermal Energy Storage

As mentioned previously, one of the advantages of solar thermal energy collection is that the energy collected can be more easily stored. This is advantageous because it allows solar thermal power plants to store energy during the day so that it may later be used during hours of peak energy usage, the night, and on cloudy days.

Thermal energy can be stored in many different ways. Many home systems simply use water as a means of storage. The advantages of this comes from water's high specific heat, meaning that it is more difficult for water to gain and lose thermal energy. In an insulated container, hot water can be collected in the summer, and used in the winter to heat a house. However, water is limited in that it can only be heated to 100 degrees Celsius. Because of this, some systems use solids like rocks, concrete, or iron to store thermal energy. These solids are often immersed in water or synthetic oil and kept inside an insulated chamber. While solids have a lower specific heat than water, they can reach much higher temperatures. For Solar Thermal plants, the heat transfer fluid itself can be used to store thermal energy by keeping hot heat transfer fluid in an insulated tank.

sources:
  Glatzmair G. Summary Report for Concentrating Solar Power Thermal Workshop. Rep. no. NREL/TP-5500-52134. Washington D.C.: US. Dept. of Energy, 2011. Print.

Chen, C. Julian. Physics of Solar Energy. Hoboken, NJ: Wiley, 2011. Print

Dinçer, İbrahim, and Marc Rosen. Thermal Energy Storage: Systems and Applications. Chichester: Wiley, 2011. Print.