Characteristics of Solar Hot Water Tanks

The most common application of solar thermal energy is in systems designed to heat domestic hot water. The most important component of such systems is the hot water tank, which is used to store solar energy. A heat exchanger transfers the heat generated from the collector to the well-insulated tank, allowing it to be stored for hours or even days until it is consumed, for example, when providing a bath or shower. The common characteristics of solar hot water tanks compared to conventional boilers or hot water tanks are as follows:

1. For domestic use, the specific volume—and therefore the storage capacity—of solar tanks is considerably higher.

2. The structural shape of the solar tank must be elongated and slender, supporting thermal stratification within the tank. The cold water from the solar heat exchanger at the bottom of the tank is used, while the heated water from the tank is generated. A pipe enters the heater at the top of the tank, ensuring that the hot water is consumed first. 3. Insulation prevents heat loss, allowing the store to be opened during the day or simply for a short period of time.

4. Solar water transfer to the tank. There is a heat exchanger at the bottom of the tank. If the water in this area of the tank falls below a specified temperature, heat can be received from another source. An additional heat exchanger is located at the top of the tank. This ensures that hot water is always available.

Typically, a solar hot water tank is sized to double the amount of water you can afford to spend per day. A standard tank for a household of four people, with a head of household and a daily usage of 40 liters of hot water, would hold 300-320 liters. Because larger households require more water to maintain a clean and healthy environment, as well as to meet various needs, a solar hybrid system is better suited for these users.