How do solar hot water systems work?

Are you fed up of getting huge electricity or gas bills? It is time to switch to the more environment and pocket-friendly option – solar energy – if you haven’t already! All around the world, millions of people are already using energy from the sun to get heat or electricity for various needs.

While the popularity of solar cells, also called photovoltaic cells or solar electric panels, maybe recent, solar thermal panels have been commonly available for decades. These panels utilize sunlight to heat water and are the basic components of solar hot water systems, which can save you a good amount of money spent on fuel. A typical system can give you anything between 10 to 90 per cent of hot water and would be able to pay for itself it only 10 to 15 years (maybe even sooner in case you use them for a swimming pool or something similar).

Before you decide to make the switch, let us explain to you how these systems work.

The main parts of a solar hot-water system are:

  • Collector
  • Hot water tank
  • Heat exchanger
  • Pump
  • Control system

Theoretically, the solar hot-water systems which are placed on the rooftops work in this way:

  1. The water flows in a circuit that is spread throughout the collector of your panel. This water is heated due to the sunlight.
  2. This means that the water that leaves the collector is hotter as compared to the water which is entering it. The water carries this heat to your hot water tank.
  3. When this water reaches your tank, it doesn’t go inside it to fill it up. On the contrary, it goes into a pipe placed on one side of the tank and comes out of another pipe on the other side. It passes through a heat exchanger (a coil made out of copper pipes) and passes on its heat here.
  4. Hot water can be used from your tank whenever it is needed, and this won’t have any effect on your panel’s operation. A solar panel obviously can only produce heat during the day, so another heat source may be needed for your tank, depending on your needs. For this purpose, you may use an electric immersion heater or a gas boiler.
  5. After the heat exchanger has absorbed heat from the heated water, it returns the cold water to the panel.
  6. An electric pump is used to keep the water flowing between the water tank and the collector (through the circuit). It may be powered using a photovoltaic cell or the common electricity supply.

In practice, there may be complications due to weather changes. For instance, when in winter you may not have any useful heat from the sun or if it is extremely cold, you may not get enough hot water, or your system may be in danger of freezing up. To solve these problems, you may occasionally pump hot water through your system. This is the reason why a solar hot water system typically has two interlinked water circuits, such as the hot water systems services in Preston & Brunswick.

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