Classify different types of solar collectors and show the construction details of flat plate
collector.
Answers
Answer:
THE DIFFERENT TYPES OF SOLAR THERMAL PANEL COLLECTORS
Explanation:
EVACUATED TUBE SOLAR THERMAL SYSTEMS
The evacuated tube solar thermal system is one of the most popular solar thermal systems in operation. An evacuated solar system is the most efficient and a common means of solar thermal energy generation with a rate of efficiency of 70 per cent. As an example, if the collector generates 3000 kilowatt hours of energy in a year then 2100 kilowatt hours would be utilised in the system for heating water. The rate of efficiency is achieved because of the way in which the evacuated tube systems are constructed, meaning they have excellent insulation and are virtually unaffected by air temperatures. The collector itself is made up of rows of insulated glass tubes that contain copper pipes at their core. Water is heated in the collector and is then sent through the pipes to the water tank. This type of collector is the most efficient, but also the most expensive.
There are two main types of tubes that are used inside the collector which are glass-glass and glass-metal. The glass-glass version uses two layers of glass fused together at both ends. The double glass tubes have a very reliable vacuum but reduce the amount of light that reaches the absorber inside. The double glass system may also experience more absorber corrosion due to moisture or condensation forming in the non-evacuated area of the tube. The second kind of tube is a glass-metal combination. The glass-metal combination allows more light to reach the absorber and reduces the chances of moisture corroding the absorber.
The cylindrical shape of evacuated tubes means that they are able to collect sunlight throughout the day and at all times in the year. Evacuated tube collectors are also easier to install as they are light, compact and can be carried onto the roof individually. What’s more, the tubes can be replaced individually if one becomes faulty, avoiding the need to replace the whole collector. The system is an efficient and durable system with the vacuum inside the collector tubes having been proven to last for over twenty years. The reflective coating on the inside of the tube will also not degrade unless the vacuum is lost.
FLAT PLATE SOLAR THERMAL SYSTEMS

are another common type of solar collector which have been in use since the 1950s. The main components of a flat plate panel are a dark coloured flat plate absorber with an insulated cover, a heat transferring liquid containing antifreeze to transfer heat from the absorber to the water tank, and an insulated backing. The flat plate feature of the solar panel increases the surface area for heat absorption. The heat transfer liquid is circulated through copper or silicon tubes contained within the flat surface plate.
Some panels are manufactured with a flooded absorber that involves having two sheets of metal and allowing the liquid to flow between them. Using a flooded absorber increases surface area and gives a marginal boost in efficiency. The absorber plates themselves are usually made from copper or aluminium and are painted with a selective heat coating which is much better at absorbing and retaining heat than ordinary paints.
In an area that produces an average level of solar energy, the amount of energy a flat plate solar collector generates equates to around one square foot panel generating one gallon of one day’s hot water.
The flat plate panel design utilises many different absorber configurations with the main design being the harp configuration. The harp design is usually used in low pressure thermosyphon systems or pumped systems. Other configurations include the serpentine which uses a continuous S shaped absorber and is used in compact hot water only systems which do not utilise space heating. There are also the flooded absorber systems and boundary absorbers which use multiple layers of absorber sheet where the heat is then collected in the boundary layer of
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THERMODYNAMIC PANELS
Thermodynamic solar panels are a new development in solar thermal technology. They are closely related to air source heat pumps in their design but are deployed on the roof or walls like regular solar thermal panels and do not have to be south facing. The concept behind thermodynamic solar technology is that it acts like a reverse freezer and they differ from conventional solar thermal in that they do not use solar radiation to heat up heat transferring liquids.