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The solar evacuated tube system is a type of solar water heater, a system that harnesses the heat of the sun to heat water using solar energy.
Below are some common types that buyers can consider when purchasing these systems:
Direct systems
In direct systems, water flows directly through the evacuated tubes. These systems are most suitable in areas where temperatures do not fall below freezing. This is because the water in the tubes will freeze and cause damage in such conditions.
Indirect systems
Also known as anti-freeze systems, indirect systems use a heat transfer fluid instead of plain water. This fluid is heated in the evacuated tubes and then passed through a heat exchanger in a storage tank. Here, the heat is transferred to water, which is what will be used for consumption. These are ideal for colder climates where freezing could be a problem.
Passive systems
Evacuated tube collectors can also be found in passive systems. These systems rely on natural convection to circulate water. When water is heated in the collector, it rises, and cooler water sinks to take its place. There are two types of such systems – thermosiphon systems, where the solar water heater is installed above the storage tank, and convectional systems, which use more complex mechanisms and are more expensive.
Active systems
Active systems use electric pumps to circulate water or heat transfer fluid between the collectors and the storage tank. These systems are more complex compared to passive systems. However, they are useful in some situations where passive systems cannot be practical. For example, active systems can be used when the solar water heater has to be installed far away from the storage tank.
Flat plate solar collectors
This is a common type of solar collector, although less common than the evacuated tube collector. Flat plate solar collectors consist of a flat, rectangular box with glass cover on top to allow sunlight in and absorbing plates inside that absorb solar radiation and convert it into heat.
When purchasing solar tube collectors, buyers should keep these factors in mind:
Climate
Buyers should consider the climate in their area when choosing solar evacuated tubes. Evacuated tubes perform well in cold and cloudy weather because they use the selective coating to trap heat inside the tubes. Therefore, they are more suitable for cold weather than flat-plate collectors, which may struggle to absorb heat in such conditions.
Installation angle
Solar evacuated tubes systems are designed to be installed at angles of 10 to 50 degrees. These angles should be relative to the horizontal surface where the system is installed. This is to ensure that the tubes are able to collect the maximum amount of sunlight throughout the year.
Water quality
Buyers should remember that the water quality in their area can also affect the performance of these systems. If the water in their area is hard, meaning it contains high levels of minerals such as calcium and magnesium, these minerals can build up inside the tubes and damage the selectively coated material. This ultimately affects the system's ability to absorb heat. To mitigate this, buyers may consider installing a water softener or using a different type of solar heating system that is more resistant to damage caused by hard water.
Budget and maintenance
In general, indirect systems are more expensive than direct systems. This is because they require additional components like a heat exchanger and a pump. On the other hand, direct systems are cheaper and easier to install. However, they may not be as effective in colder climates. When selecting these systems, buyers should factor in both the initial costs and long-term maintenance expenses to avoid choosing a system that will be expensive to maintain in the long run.
Regular inspections
Buyers should regularly check their solar evacuated tubes for any visible damage. This includes cracks, dents, or signs of wear and tear. They should also ensure that all the components which include the storage tank, pipes, and pumps are in good condition. Any leaks or corrosion should also be repaired immediately. These may cause smaller issues to develop into bigger problems in the long run.
Cleaning
Solar evacuated tubes need to be kept clean to ensure optimal performance. Dust, dirt, or debris can reduce the system's ability to absorb sunlight. Therefore, buyers should gently wash the outer surface of the tubes using soapy water at least once a month. It is important to note that they should do this carefully so as not to damage the glass or the selective coating inside the tubes.
Checking the water quality
Water quality can significantly affect the performance of solar evacuated tubes over time. Buyers should check for any signs of limescale or sediment buildup inside the tubes. These may be caused by hard water or impurities in the water used in solar systems. If they notice any such signs, they should flush the system with a suitable descaling solution or install a water treatment system to prevent further accumulation of these deposits.
Pressure check
Buyers should check the pressure in the solar system at least once a year. A drop in pressure may indicate leaks in the system, while excessive pressure may cause damage to pipes. Buyers should always consult experts to help them check the pressure and provide solutions in case there are any problems.
Maintenance by professionals
Buyers should have their solar evacuated tube heater serviced by professionals at least once every two years. Experts will carry out a more thorough inspection and maintenance work where necessary. These service statutes will be able to check for issues that may be hard to spot for the average person. Some of them may even offer replacement parts or carry out repairs themselves as they have access to all the right equipment and experience. Buyers should also consider warranties when purchasing the systems since they cover maintenance and repairs.
Repairs buyers can do
For minor repairs like fixing leaks, patching damaged insulation, and replacing broken vacuum tubes, buyers can easily do them on their own using video tutorials and articles on the internet. However, there are repairs that require professional help. These include bleeding and refilling the system, replacing system components, and repairs that require specialist tools or skills. For these kinds of repairs, buyers should hire experts.
Solar evacuated tube collectors have the following benefits:
Efficient heat retention
Evacuated tubes use the principle of the greenhouse effect together with the selective coating on the inside of the tubes to efficiently retain heat. The selective coating absorbs solar radiation and converts it into heat while the vacuum between the inner and outer tube reduces heat loss through convection and radiation. These qualities allow the tubes to function well in a variety of weather conditions.
High performance in different weather conditions
Evacuated tubes are capable of absorbing both direct and diffuse solar radiation. This makes them effective even on cloudy days. They are also able to operate efficiently in low temperatures. This is because the vacuum acts as an insulator, reducing heat loss and allowing the tubes to retain the absorbed heat. This diffuseness and versatility make evacuated tubes suitable for different climates and seasonal conditions.
Flexibility in installation
Evacuated tube collectors are relatively easy to install and can be mounted on roofs with different angles and orientations. They can also be integrated into existing heating systems or used in new constructions. This flexibility makes them a popular choice for both residential and commercial applications.
Scalability
Several solar evacuated tubes can be easily added to increase the system's capacity. This makes them a scalable option for users who want to expand their solar heating system in the future.
Durability
Evacuated tubes are manufactured with strong materials that can withstand harsh weather conditions. They also have long lifespans, usually ranging from 15 to 25 years. This makes them a long-term investment for buyers.
Cost savings
Although the initial installation costs for solar evacuated tubes might be higher than traditional heating systems, the long-term savings on energy bills make them a more economical choice over time. These systems also qualify for various incentives and rebates, which can help offset the initial costs. Therefore, buyers should always check these offers before purchasing the systems.
Yes, evacuated tube collectors can perform well in tropical climates. These are suitable for regions with strong sunlight for most of the year. They effectively capture solar radiation and provide reliable hot water. However, in areas with excessively high temperatures, it may be necessary to implement measures to prevent overheating or explore options for providing cooling systems.
Evacuated tube collectors need regular inspections, at least once a month, to ensure they are in good working condition. This includes checking for damage, cleaning dust and debris off the tubes, and making sure all other components are also fine. Water quality should also be monitored to prevent limescale buildup inside the tubes. Buyers should also have their systems serviced by professionals at least once every two years.
Unfortunately, while solar evacuated tubes can be especially beneficial for tropical regions, limited accessibility and availability of resources currently prevent many people in low-income areas from enjoying the systems. However, initiatives promoting affordable and accessible solar technologies hold potential for future benefits.
Buyers have various financing options to help them manage the initial costs of purchasing solar evacuated tubes. These include residential solar loans, power purchase agreements, leases, and incentives and rebates. They can also consult financing professionals to help them with the various options and strategies available to them.
