Solar water heating systems harness the energy from the sun turning it into heat energy that is later used for domestic hot water needs, industrial procedures, pool heating, and water heating in nursing homes and hospitals, restaurants, and canteens. Solar water heating is reliable, limits greenhouse gas emissions by 70%, and has a cost saving of up to 60%.
Despite all these possible benefits, many users of solar water heating systems lack enough knowledge to guide them and get the best from their systems. Solar water heating systems must be properly installed and maintained and adhere to all the science associated with such systems.
Ignoring basic scientific installation and maintenance procedures will result in clogged pipes, debris buildup within the system, sediment, and dirt. Additionally, proper installation and maintenance of your solar water heating system will guarantee continous functionality during extreme weather and reduce the chances of severe damage to the heating system.
Understanding the different types of solar water heaters is vital; you can make informed decisions about the type of system to install depending on your needs and the number of people and elements dependent on your system.
1. Direct Circulation Systems
In this system, a pump transfers water to the collectors, where solar energy is available to heat the water. The water is then returned to the storage tanks to be stored until when needed. A direct circulation system consists of a differential thermostat that compares the temperature difference at the outlet and the storage tank. This system produces the best operating efficiency since it does not have nighttime heat loss.
2. Indirect Water Heating Systems
This method is mostly applied in areas with extreme weather. It uses elements such as diluted antifreeze circulating through a collector. This process generates heat and later gets transferred to the water supply using a heat exchanger. Indirect systems are efficient in places with enough space, and homes with a complimentary HVAC system.
How To Improve the Efficiency of Solar Water Heating Systems
Before improving the efficiency of any system, it’s important to know and understand the different components that make up that system. A solar water heating system comprises different components that include:
• Storage tank
• Evacuated tubes
• An external water supply source
• Mounting frame
1. Insulating The Storage Tank(s)
The system’s efficiency can be improved by providing effective insulation materials that reduce the temperature difference between the storage tank and the collector. Determining an optimum operating temperature is essential; this can be done by measuring the effectiveness of different materials such as:
Polyurethane
Cork board
Fiberglass wool batts
Wood shavings
Sawdust
Polystyrene or Styrofoam
The materials mentioned above are some of the best insulating materials today. Generally, they provide good thermal insulating properties, high resistance to water absorption, low moisture permeability, and high mechanical strength. Furthermore, materials like fiberglass are resistant to fire and microbiological attacks, resistant to most chemicals, and available in various forms.
The effectiveness of these materials can be measured using a pyranometer, an actinometer used to measure solar irradiance. Using a pyranometer is important since pyranometers have a solar radiation spectrum that extends to 2,800 nm, which is well within the solar radiance of these materials.
2. Integrating Oil In Evacuated Tubes
Thermal oil is inserted in the evacuation tubes to improve the heat transfer through the tubes so that the heat transfer from the evacuated tubes’ inner surfaces to the pipes becomes convection via the oil. Furthermore, research has shown that replacing a fin with foamed copper and oil significantly changes the mode of heat transfer to conduction and convection.
These integration methods also improve the heat transfer rate through the tubes, improve heat energy storage even after sunset, improve contact between inner tubes and the heat pipes, and fill the air gaps with an effective heat transfer medium.
3. Using Reflectors to Improve the Efficiency of Solar Collectors
Collectors play a crucial role in solar heating since they collect the sun’s energy and transform the sun’s radiation into heat energy. Therefore, making the collector as efficient as possible is important by integrating different elements, such as reflectors.
When used alongside solar collectors, reflectors increase the collectors’ reflectivity by diffusing the sun’s radiation toward the collector. The reflector is designed to change its direction, facing the sun as it changes direction. The reflector then absorbs this energy, converts it into heat energy, and feeds the collector. This combination improves the collector’s efficiency by more than 10%.
Another crucial aspect that is often overlooked is the durability of photovoltaic cells. These cells are responsible for converting solar energy into usable electricity. Photovoltaic cells are less durable compared to concentrated photovoltaic cells. They differ in their individual efficiency levels. Concentrated photovoltaic cells have a 46% efficiency level compared to photovoltaic cells, which have an efficiency level of up to 22%.
These notable differences greatly influence the output of solar collectors. With this in mind, using durable cells and installing your system in less shaded areas provide optimum results and guarantee the durability of your system.
Additionally, integrating your heating system with management software gives accurate results and helps improve the management of the entire system. Applications such as HelioScope and Photonik can be an added advantage, especially for small and medium solar companies. These computer software provide accurate energy consumption data and notify you when efficiency levels drop.
4. Choose A Suitable Mounting Option for Solar Collectors
While ground mounting is ideal since it minimizes vertical runs, reducing installation costs and provide easy service and assembly procedures, it is not a proper method for installing solar collectors. Ground mounting can be more expensive since it may require additional installation items such as concrete foundation and permits, therefore increasing installation costs.
Research has shown that pitched roof mount is the most efficient method to mount solar collectors because this method avoids obstacles such as houses and trees and has an unobstructed view. Pitched roof mount installation should be done with extreme care, considering factors such as the roof truss system, the system’s weight, and understanding the inclination of the roof.
A pitched roof mount is typically designed to withstand extreme weather; it has strong support components to support the weight of the entire system.
Conclusion
Solar heating systems provide reliable water heating solutions when properly installed and maintained. Also, understanding the water needs and the performance of your system provides a clear understanding of the various improvement methods to be applied. Consulting qualified engineers when installing solar heating systems will save you the overall maintenance cost and reduce the risk of damage to your system in the long run.
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