Solar water heating

A solar water heating system is used to heat water using solar energy. This is composed of solar thermal collectors, a fluid system, and a tank or other kind of reservoir to store the water. The fluid system is used to move the heat from the collector system to where it is needed. The main focus of solar water heating systems is on domestic water heating, but the same principles apply to all solar systems. However, the system is also used is heating swimming pools.

Most used energy sources (gas or electricity) are quite expensive. Because the solar energy is completely free, the solar water heating system delivers a very cost effective method to have heated water. The initial implementation of the system is expensive. However, the costs of heated water are greatly reduced. For example, a 56ft² solar water heater costs around $7,500 and saves approximately $530 each year. This means that the system has a payback in 14 years.

The efficiency of the solar water heating system depends on location. In northerly locations, efficiency is decreased due to lower solar power and colder environment. The system is very efficient in the summer, on cloudless days, between April and October. In the UK, the installation costs used to be very high, reaching £9,000. However, recently, this has been reduced to approximately £3,000. The average payback in the UK is around 12 years, taking in consideration the rise in gas price.

Solar water heating systems use a collector to collect solar energy. This collector is placed on the roof or on a wall facing the sun. The basic system pumps the water from the tank to the collector, where it is heated, and then back into the tank. There are two types of systems available to the public at the moment: the compact system and the pumped system. The compact system is also known as a passive system or monobloc system and is composed of a solar collector, a tank and all connecting pipes. In sunny regions, for a four person home, a tank of 200 to 300 liters is enough. Studies show that the passive system can save up to 4.5 tones of greenhouse gas emissions each year and can work up to 25 years without needing major maintenance. Because they contain no electrical components, passive systems are generally more reliable, easier to maintain, and possibly have a longer work life than active systems. The pumped system is also known as active system. It can be a zero carbon or a low carbon system. The low carbon generally uses electric energy to circulate fluid in the system. Active solar water heaters rely on electric pumps, and controllers to circulate water, or other heat-transfer fluids through the collectors. These systems have more sophisticated safety features and permit more measurements of the produced energy. The new zero carbon systems use solar electric pumps to circulate the fluids.

Choosing either an active system or a passive system is entirely at your discretion. A typical residential solar water-heating system reduces the need for conventional water heating by about two-thirds. It minimizes the expense of electricity or fossil fuel to heat the water and reduces the associated environmental impacts. You must take into consideration all the factors that may affect the efficiency of your solar water heating system, such as solar energy in your area, number of cloudless days per year, average temperature and many more. Before choosing any system, you must read the technical specifications to make sure the system is useful to you. You must make sure that you familiarize yourself with manufacturers instructions, water company regulations, planning permission if required, or any other laws or regulations in place at the time of installation and that any person carrying out an installation does so at their own risk.