Solar water heating systems, also known as solar thermal systems, utilize the sun’s energy to heat water and store it in a hot water cylinder or thermal store. A solar water heating system will not deliver 100 per cent of the hot water necessary throughout the year since the quantity of available solar energy changes throughout the year. A traditional boiler or immersion heater is usually employed to make up the difference.
Larger solar hot water arrays may also be set up to assist with your house’s heating. However, because the quantity of heat provided is usually little (less than 10% of the home’s heating needs), it is rarely regarded as useful. The majority of solar hot water systems are only intended to supply hot water for bathing, showering, and hot taps.
A sun-facing collector warms a working fluid, then stored for later use. SWH can be active (pump) or passive (non-pump) (convection-driven). They either utilize water or a combination of water and a working fluid. They are heated either directly or by the use of light-concentrating mirrors. They can run on their own or with electric or gas heaters. Mirrors may focus sunlight into a smaller collector in large-scale setups.
Working of a Solar Water Heater
The solar water heater transforms light into heat by absorbing it through a collector on the roof. It uses a circulating pump to transfer the heat to a water tank. The thermal regulator initiates this exchange only when the collector is hotter than the water in the tank. This keeps the circulating pumps from wasting power. On the other hand, it reduces overheating.
The sun is utilized to heat the water in a solar water heater. It comprises mainly of the following components:
- A roof-mounted thermal panel (solar collector).
- A hot water storage tank.
- A thermal regulator, as well as a circulation pump to transport solar energy from the collection to the tank.
The collectors’ efficiency is maximum during midday in the summer when the sky is clear, and the collectors face south.
When there isn’t enough sunshine, the water is warmed, and a backup mechanism kicks in to get the temperature up to the needed level. As a result, this technology may create hot water at a consistent temperature all year without producing any CO2. Solar water heaters are classified based on the collector and circulation system used.
Types of Collectors
Batch collectors – Integrated Collector-Storage (ICS) systems heaters that heat water in tanks.
Water can linger in the collector for lengthy periods if home demand is minimal, making it quite hot. A tempering valve protects against scalding at the faucet. It adds cold water to the mix to lower the temperature of the water before it reaches the tap. Closed-loop circulation systems are incompatible with batch collectors. In colder climates, they are rarely utilized.
Flat-plate collectors – Copper tubes are attached to flat absorber plates in flat-plate collectors. A set of parallel tubes joined at each end by two pipes, the inlet and outlet manifolds are typical. The flat plate assembly is housed in an insulated box with tempered glass on top.
Evacuated Tube Collectors – The most effective collectors have evacuated tube collectors. A bigger glass tube surrounds a glass or metal tube carrying the water or heat transfer fluid. Because the area between them is a vacuum, the fluid loses very little heat.
System of Circulation
Direct System -Water is circulated through solar collectors and heated by the indirect sun systems. After that, the hot water is either held in a tank, delivered to a tankless water heater, or utilized immediately.
Closed-loop, or indirect System – Closed-loop, or indirect System, systems transmit heat from the sun to water in a storage tank using a non-freezing liquid. The sun’s thermal energy heats the fluid in the solar collectors. The heat is then transferred to the water bypassing via a heat exchanger in the storage tank. After then, the non-freezing fluid returns to the collectors.
Active Systems – Electric pumps, valves, and controls transfer water from the collectors to the storage tank inactive, or forced-circulation, systems. In the United States, they are relatively frequent.
Passive Systems – Pumps are not required in passive systems. Natural convection transports it from the collectors to the storage tank as the water heats up.
Here are some advantages of Solar Water Heater
Size: Homeowners must have enough storage to meet 90 to 100 per cent of their hot water needs, so proper sizing is critical. The amount of storage space available is also a factor to consider. Up to three people can fit in a 50- to 60-gallon storage tank, four people in an 80-gallon tank, and six in a bigger tank.
Less Space: Solar thermal panels take up less area than photovoltaic panels in most cases. It takes fewer solar panels to heat water than generate enough electricity to run a home.
High efficiency: Approximately 80% of the sun’s light is converted into the thermal energy required to heat water in residence.
Savings: Two or three panels are less expensive than bigger household installations. You also save money on gas heating system fuel expenditures.
Low upkeep: After installation, solar water heaters require little maintenance and can last 20 years.
Lower carbon footprint: A home may be more eco-friendly, and tax advantages for employing renewable energy may be available.
Environmental benefits of Solar Water Heater
The primary goal of installing a solar water heater is to supply hot water using renewable energy sources such as the sun. Solar appliances are both environmentally friendly and safe for people’s health. As a result, many individuals nowadays opt to use solar equipment in their homes. Solar water heaters are advantageous in various aspects, including environmental, financial, and socioeconomic. Solar water heaters do not generate any toxic gases, unlike other fossil fuels, which emit a substantial quantity of carbon dioxide that harms the environment’s breathing layer.
Solar water heaters do not provide hot water because of the direct heating process. As a result, they have the potential to cut carbon footprint emissions. There are no greenhouse gases or other pollutants produced by solar water heating. One solar water heater may save over 50 tonnes of carbon dioxide over 20 years when compared to an electric or natural gas water heater.
Most heating systems use fossil fuels, which emit pollution; however, all of the energy saved by solar water heating is used to reduce pollution, which would otherwise contribute to our problems of poor air quality, poor health, smog, and global climate change, a problem that requires immediate action. The repercussions of using fossil fuels to create power and heat are just now beginning to be understood by climate scientists. They believe that global warming will increase sea levels and a rise in the frequency and intensity of devastating storms though they don’t know how much or when this will happen.
At the present pace of use, world petroleum resources will not last a newborn born today until 40 years old. Many people predict that the current pace of consumption will not remain constant but rather climb, reducing the 40 years. One method to extend these limited resources is to use solar water heating. An average family’s annual energy consumption with an electric water heater is about equivalent to a medium-sized car driven 12,000 miles per year at an average fuel efficiency of 22 miles per gallon, or around 11 barrels of oil. A household solar water heating system may save your hot water expense and usage by 50 to 80 per cent while also reducing pollutants.
What are Greenhouse Gas Emissions?
According to the EPA (Environmental Protection Agency), Greenhouse gases trap heat and cause global warming. Carbon dioxide is a greenhouse gas released into the atmosphere when fossil fuels such as natural gas, coal, and oil are burned. Transportation (28 per cent), energy (28 per cent), industry (22 per cent), commercial and residential (11 per cent), and agricultural (11 per cent) are the leading sources of greenhouse gas emissions (9 per cent). As can be seen, power generation contributes significantly to greenhouse gas emissions. CO2 emissions, which contribute to the greenhouse effect, are a significant issue for our world.
If greenhouse gas levels continue to grow, the average temperature on Earth’s surface will rise, affecting the composition of the atmosphere and dissipating energy in all directions.
How Solar Energy Lowers Your Carbon Footprint
Solar energy minimizes CO2 emissions by offering a clean, renewable energy source. The solar panels on your roof receive energy from the sun and convert it to sound power. This method does not need the usage of fossil fuels or other goods, and no energy is lost because it may be stored on the grid for later use. Furthermore, solar energy prevents water pollution since PV panels, unlike other industrial processes, do not require water to function. Solar energy converts sunlight into power without using local water supplies, and it does not damage our rivers as fossil fuels do.
By converting to solar-powered electricity, people can substantially lower their household’s carbon footprint, which is the total greenhouse gas emissions created by your home. Driving less, eating more local and organic food, establishing a garden, line-drying clothing, and unplugging your electronics at night are all methods to support this lifestyle.
Disadvantages of Solar Water Heater
One downside is maintenance; however, most systems do not need much attention. On the other hand, scaling happens when minerals suspended in household water form calcium deposits in the System. Scaling may be avoided by using water softeners or mild acidic chemicals like vinegar. It only has to be done every three to five years, depending on the water condition.
Another issue to consider is corrosion. Any iron or steel item in an open-loop hydronic solar system can rust. Plumbing components comprised of copper, brass, bronze, stainless steel, plastic, or rubber are more resistant. To prevent corrosion, storage tanks should be coated with glass or plastic.
Active systems can also overheat if the storage tank isn’t the right size for the collector. The usual guideline is that 1.5 gallons of storage should be provided for every square foot of collector. Such a disadvantage can be avoided if this is kept in mind.
Other drawbacks include
- Solar thermal panels, unlike photovoltaic panels, only heat water.
- Solar heaters require enough roof space to be installed.
- Solar water heaters must be exposed to direct sunlight to work.
- On gloomy, rainy, or foggy days, the system will not work.
- It is advised that the pump and antifreeze be checked once a year.
- A new hot water cylinder is required for installation.
Furthermore, heating is only available throughout the day. That isn’t to say that there won’t be hot water accessible at night. An insulated storage tank may keep water at a constant temperature so that water heated during the day can be utilized at night.
Solar water heaters offer benefits and drawbacks, but they are consistent and efficient. Planning
and correct installation enables homeowners to get the most out of them while avoiding some of the drawbacks and getting all of the benefits that the proper System and size can provide.
Solar water heaters are another step towards global change. Their house will make a difference, and it may inspire others in the community to follow suit! People may believe that converting to solar power will be good only if everyone does so, but change must begin somewhere.