Solar water heaters are devices that usesolar energy to heat domestic hot water. They use thermal solar panels to capture the sun’s heat and transmit it to a hot water tank. This heating solution offers many advantages, such as lower energy bills and reduced gas or electricity consumption.
How solar water heaters work
Solar water heaters use solar energy to produce domestic hot water. The operating principle is simple: solar thermal collectors, installed on the roof of a home, capture the sun’s energy and transmit it to a heat-transfer fluid, generally composed of water and antifreeze (Hcfc), which circulates in a closed circuit. This heated fluid then passes through a heat exchanger located in a hot water tank, where it transfers its heat to the domestic hot water. This system makes it possible to heat water without using fossil fuels such as gas or electricity.
Thermal solar panels are the core element of a solar water heating system. They are generally installed on the roof, facing south to maximize exposure to the sun. Their surface area varies according to the size of the system, the household’s hot water needs and the amount of sunshine in the region. In France, for example, it’s common to install between 2 and 4 m² of solar thermal panels for a family of 4.
The hot water tank, also called cumulus or reservoir, stores the domestic hot water produced by the solar water heater. Its capacity depends on the needs of the household, but is generally between 200 and 500 liters. Some solar water heaters are equipped with a back-up system, such as an electric resistance or a gas boiler, to ensure hot water production in the event of low sunshine or high demand.
Types of solar water heaters
There are several types of solar water heater:
- Individual solar water heater (CESI): This is the most common system, consisting of solar thermal panels and a hot-water tank, adapted to a family’s needs.
- Thermodynamic solar water heater: This system combines a solar thermal panel and a heat pump to optimize hot water production, even in low-sunshine conditions.
- Comparison with other types of water heater: Solar water heaters offer advantages over electric and gas water heaters in terms of energy savings and environmental impact.
Installation and costs
Installing a solar water heater is a profitable long-term investment. The price varies according to size, materials used, complexity of installation and labor. In France, financial aid is available to encourage individuals to adopt this renewable energy. These include the French tax credit for energy transition (crédit d’impôt pour la transition énergétique – CITE), the zero-rate eco-loan, the energy bonus, as well as local and regional grants. Reduced VAT of 5.5% also applies to energy renovation work.
Solar heating is an attractive solution for reducing energy bills and carbon footprints. Depending on the region and the amount of sunshine, a solar water heater can cover between 50% and 80% of a household’s domestic hot water needs. The savings on energy consumption are therefore substantial. What’s more, maintenance of a solar water heater is relatively straightforward, making it a reliable, long-lasting system.
Companies and products on the market
Several manufacturers offer quality solar water heaters:
- Sunpower: Sunpower is an American company specializing in the production of solar panels and solar heating solutions.
- Atlantic: Atlantic is a French company offering a wide range of solar water heaters to suit different needs and budgets.
- Other well-known manufacturers: Many other companies, such as Viessmann or Saunier Duval, also offer high-performance solar water heaters.
Advantages and disadvantages of solar water heaters
Advantages
- Energy savings: Solar water heaters considerably reduce energy bills by using the sun’s free energy.
- Environmentally-friendly: By using solar energy, these systems help reduce greenhouse gas emissions and the consumption of fossil fuels.
- Financial assistance: Numerous financial incentives are available to facilitate the installation of solar water heaters and reduce their cost.
- Longevity: Solar thermal panels have a lifespan of 20 to 30 years, making them a long-lasting investment.
Disadvantages
- High initial cost: Installing a solar water heater can represent a substantial investment, although financial assistance can help reduce the cost.
- Climate-dependent: The performance of solar water heaters can be affected by low sunlight levels, sometimes requiring a back-up system to ensure hot water production.
- Space requirements: Solar thermal panels require an available surface on the roof or ground, as well as space for the hot water tank.
Regional examples
Solar water heaters are becoming increasingly widespread in various regions of France:
- Lyon: The city of Lyon supports the installation of solar water heaters by offering financial assistance and encouraging awareness-raising initiatives.
- Lille is also committed to promoting solar water heaters, with financial incentives and local projects to facilitate their adoption.
- The city of Vannes actively supports the installation of solar water heaters and other renewable energy solutions to promote the region’s energy transition.
The development of solar water heaters in France is supported by regulations such as the RT (Réglementation Thermique), which imposes energy standards for new buildings and renovations. These regulations encourage the use of ecological and economical heating solutions, such as solar water heaters, to meet domestic hot water needs.
Companies and models
Here are a few well-known companies in the field of solar water heaters and their flagship models:
- Atlantic is a French company specializing in heating and hot water solutions. Among its flagship products is the “SOLERIO Optimum” solar water heater, which comes in a range of storage capacities, from 200 to 300 liters. This model uses flat-plate solar thermal collectors to capture solar energy and heat water.
- Viessmann is a German company and one of the world leaders in heating and air-conditioning systems. Its “Vitosol” solar water heater comes in several versions, using flat-plate or evacuated-tube solar collectors for high efficiency. The associated “Vitocell” hot water cylinders are available in different capacities to suit the needs of every household.
- Bosch is a German company well known for its electronic and household appliance products, as well as its heating and hot water solutions. The “Compress 3000 DW Eco” model is a thermodynamic solar water heater that combines a solar thermal panel and a heat pump to ensure efficient, constant production of domestic hot water.
- Thermor is a French company specializing in heating and hot water solutions. Its flagship “EnR’sol” solar water heater uses flat-plate solar collectors to capture solar energy and heat water. The associated hot water tanks are available in capacities ranging from 200 to 400 liters.
- Sunpower is an American company specializing in solar energy solutions. Although Sunpower is best known for its photovoltaic solar panels, it also offers solar water heating solutions in partnership with other manufacturers. Sunpower’s solar water heating systems are designed to integrate seamlessly with their photovoltaic solar panels, offering a complete solution for solar energy needs.