Solar Water Heating Systems

Solar energy is the source of energy which is now in use all over the world. Different companies and researchers are introducing new ways and method to use the solar energy. The consumption of petrol and natural resources are not only harmful to the environment but they effect the economic situations as well so it is necessary for every country and for every body to have alternative sources of energy. That is why developing countries are specially putting efforts to enhance the use of solar energy. Other different sectors like house hold usage and car industry is also doing research to get as many benefits from the solar energy as possible. Solar energy is also used for swimming pool heating systems. These systems are so flexible that they could both be used indoor and outdoor swimming pools. These systems could be installed both in the cold zones as well as in the hot zones.

Solar based systems are electronically controlled and different sensors are installed in the system to keep the temperature of swimming pool at adjustable temperature rage. If the weather is hot sensors will allow the water to bypass without heating into the swimming pool and if the weather is cold sensors direct the valve to control flow. Solar systems are also used in under earth heating systems to store hot water for the home usage.

The aim behind this project is to design the solar heating system which can effectively improve the use of solar energy. The system should be cost effective in such a way that it could be easily used in homes. The efficiency of heating system should more than normal systems used in market. System should be differentiated into the parts in such a way that it could be used in many ways. If some body wants to use the system in automatic configuration or in manual configuration both could be easily installed and operated. The system could be easily adjusted in hybrid mode means either to run on electric power or solar energy. The whole system could be configured automatically in such a way that a simple lay man could also use the system by studying the manual. All parts of system should be easily available in the market and should be cheap that if some one wants to replace any of the part he could easily get the part and install in the particular place. The system should not work in such a way that if one part is not operating whole system should not stop its working although certain parameters would definitely disturb in that case for example if the heat sensor is not working properly the temperature of water could raise but will not exceed too much as fixed level is programmed in controller to stop the system.

2. HISTORY

The solar energy was explored in 1950. The background of use of solar energy is linked to space technology. The need of energy system was felt for the satellite system, because for the continuous source of energy the solar energy was considered to be the best possible solution in the space. In early era the solar energy was used with the help of black pans. As the black color absorbs maximum heat so the black pots and pans were used to heat water. The solar cell possibly can convert small part of sun light into the energy. The best rate of efficiency of solar cells is 180%. Most wide use of solar energy systems is water heating, cooling system and energy for space technology.

3. SOLAR ENERGY

Solar energy is the energy radiated from the sun. The solar is related to the sun. The components of solar energy are light from the sun and also the heat from the sun. The sun is providing energy to the humans and other creature from very long time. The technological innovations are occurring day by day and the use of solar energy is increasing according to the technological innovation.

There are so many parts on the earth where the day times are longer and sun remain 16 ours in whole of 24 hours. Heat in those areas is so strong that lot of energy could be extracted out from the sun light and heat by using special equipment and advance technology.

As the power resources and oil resources are getting scarce on the earth every country is in the search of finding the new resource of power generation that could replace the use of oil and gas. Every country is striving to achieve fruitful results before the oil resources obsolete. They are also trying to use the secondary solar resources of power which are wave power and wind. The solar energy used by human being is very small as compared to total energy daily falls on the earth. The solar energy absorbed by the earth’ atmosphere in one hour is more than the total energy used by the whole world in one year. According to the facts and figure it is around 3,850,000 EJ per year which is absorbed in the earth atmosphere.

4. CATOGARIES OF SOLAR ENERGY

There are two basic categories of solar energy one is the active solar energy and other is the passive solar energy. Active solar energy means the extraction of solar energy form the photovoltaic cell and after solar cells electrical energy is generated and used for different purposes. Other category is passive solar energy and it is used by orienting the buildings in certain directions and from light dispersing properties. Hybrid forms of energies are also used in many areas where the solar and other sources of energies are used alternatively.

5. DESCRIPTION

The core of sun is the main source of solar energy, where the fusion reaction is occurring every time and huge amount of energy is released and the estimated amount is 3.86 x 10^26 joules per second. The part of energy which the earth receives is 174 PW of all solar radiations. Thirty percent is reflected back towards the space.

6. BENEFITS OF SOLAR ENERGY

The solar energy has many benefits and these are almost uncountable. Some of these are under mentioned.

It is the source of energy which is in huge quantity and there is no point of scarcity because the all the systems on the earth are inter-dependent. Every living creature is dependent on the light and energy of the sun. Plants can not grow without the sun light and human and animals can not survive without the plants and sun light.

Solar energy is not like other sources of energy which is harmful to the atmosphere and living creature. It is environment friendly and solar cells do not release any remnants in the air.

Solar sells are very cheap and therefore solar energy is the cheapest energy and requires no maintenance cost for the long time.

Solar energy is self sufficient for the household and for some other activities and does not require any dependence on other resources.

7. USES OF SOLAR ENERGY

With the advancement of technology and research on the solar energy has magnificently increased the use of solar energy in different sectors. Industry is also trying to cash this resource of cheap energy in its different sectors. The example of the industrial use is installing the solar panels at the remote sites where other power sources are not available and hung cost is required to establish power generating stations on those sites industries establish solar energy units and setup with relatively less cost and use the energy for different applications.

Power stations and power lines are tried to be installed on the place where there are significant number of people living around because without this the price of installation could not be achieved. But in case of solar energy the small setup could be installed even for one home in the remote areas. And this installation does not require very huge amount to be spent.

In telecommunication sectors it is tried to provide service at each and every corner although it is not possible but companies install lot of sites to strengthen the network connections. So the sites where no power lines are available solar energy systems are installed to give power to the remote sites.

Solar energy is also used for the signaling purpose for the transportation and for the offshore navigation light houses. Solar system is also used as hybrid fuel system in the cars. Lot of companies is manufacturing hybrid fuel system cars like corolla hybrid. In case of any problem the car could be directly switched to the solar based energy system.

Solar energy is also used in the home appliances and researchers are doing research to efficiently use solar energy. In many countries solar energy is water heating system and sewerage treatment plants. The roofs of buildings are made of solar cells and energy is stored in the batteries.

8. METHODS OF STORAGE

Normally solar energy is tried to collect and use at the same time. In certain conditions where the hybrid systems are installed solar energy is stored for the use at appropriate time. As the solar energy is non-constant form of energy and it is stored. It is available only for the certain duration of time and for the other time stored energy could be used.

The most common method of storing solar energy is batteries. Large batteries are attached with the solar panels with the help of charging circuitry to store the charge. These batteries are of two types

1. Nickel cadmium

2. Lead acid batteries

Lead acid batteries are cheap and for the storage purpose these batteries are mostly used. But there life time is less than the nickel cadmium batteries, these batteries discharge more electricity.

Zeolite mineral is also used to store the solar energy. Natural zeolites could be used to store energy instead of synthetic zeolites.

Water and stones are the short duration methods of energy storage. Energy obtained from the sun is directly given to water and stones using certain mediums and used according to needs in short period of time.

Another method of storing solar energy is latent heat storage method. In this method nitrates and sulphates are used to store the energy for the longer period of time.

Another system is under earth heat storage system and is usually used in homes for heating water.

9. THERMOSOLAR ENERGY

The word thermo solar is self explanatory and means the heat from the solar energy. This is the type of energy consumed in heating the water for the homes and swimming pools. The energy is also used for the climatization of plants and for other applications.

10. HEATING SWIMMING POOLS

A huge amount of energy is needed to heat up the water of swimming pool. One of the applications of solar energy is also heating the swimming pool water, although people are also using other methods to warm the water of their swimming pools. But according to the new technological innovation solar energy is tried to be used for this purpose. Because most of the swimming pools in homes and restaurants are located in open environment where solar light can easily reached so it is feasible to install any solar energy conversion system near the swimming pool. The following solar heating system is similar to the designed work. All the blocks are integrated to make one perfect system. Filters are perfectly designed and placed accurately to block dirt. The solar panel is placed right above the heat exchanger to provide maximum heat to the pipes. Valves are accurately controlled to direct the flow of water in the desired direction. Sensors are also placed right near the heat exchanger to sense the heat of exchanger and give the signal for rotation of solar panel. Other sensors are exactly placed in the water to detect the temperature of water and give the signal to programmable logic controller for panel rotation and water flow.

Figure .Solar heating system

The old traditional methods of heating swimming pools are expensive and inefficient. Lot of energy resources is wasted in heating swimming pools these resources are natural gas and electricity. Another risk associated with such system is electrocuting. The heating systems based on electric power are very risky if the people jumping into the swimming pool without checking. These systems are not only dangerous to humans but also to the environment. The pollutants release by such systems effect the environment badly. Modern methods of heating swimming pools include the option of retaining the heat into the water by using different sheets and blankets which can store heat for long time. But in case of non sunny days it is difficult for this system to heat the pool water. Keeping in view this condition other sources are alternatively used for heating purpose. The average temperature needed for heating the pool water is nearly 78 degree Fahrenheit.

11. PARTS OF HEATING SYSTEM

The heating system based on the solar energy consists of different parts and these individual parts integrate to make one system and provide cost effective solution for heating. These systems are also given the temperature control facility; user can vary the temperature of water in the pool by just adjusting the thermostat.

The main integral parts of solar heating system are as follows

Solar collector

Solar collector is the part of heating system which consists of solar cells and the heater integrated with it. The pipes for the flow of water are also attached with the solar collector. So the energy is dissipated by the solar collectors in the form of heat and this heat is directly transferred to the water. The water is then circulated through the pipes and through the filter and is controlled by different valves. Solar collectors are also of different types and manufactured according to the weather conditions. These are unglazed and glazed UV inhibitors. For enhancing the life of solar collector in the area where use is 24 hours unglazed collectors are used.

Figure . Heat exchanger

Filter

The function of filter is to purify the water before pumping in to the pipes of solar collector where the water is warmed. These filters are so efficient that they remove all debris from the water before pumped up. The filters are fitted at the start where the water is pumped because before entering into the whole system all the dirt should be removed from the system or no dirt should enter the system because this dirt could be damaging and cause blockage in the pipes. The life span of filter depends on the dirt in the water and it varies from area to area. The areas and pools where the dirt in the water is more filters should be changed in less time.

Pump

The pumps are performing the main function of flowing water from one point to the other. Pumps take the water from the swimming pools and after passing through the channels pump again into the swimming pool. This water is heated up. These pumps are given power supply from the solar panels. The idea is kept in view that not huge energy should be lost in this system. So the 12V pumps are usually used to drive the whole system, because the purpose of these pumps is to flow the water at normal pressure. Pumps used in system ensure the maximum heating quality by regulating the water flow.

Flow control valve

The flow control valves are used to control the proper flow of water through the pipes and through the channels linked with the solar collectors. The process of flow control is very important because if the water is not properly controlled to flow through the channels and pipes of solar collector and heating section lot of heat could be wasted in the air. These flow valves could be automatic and direct the water in the particular direction by opening and closing. Heat sensors are also installed in some system to detect the temperature of water and according to the temperature flow s controlled.

The sensor sends the signal to the controlling unit by detecting the temperature. And controlling unit is used to divert the direction of water flow using pump. Bypass capability is also installed in some system using the flow valves. If the temperature of water in the swimming pool is equal to the temperature of water in the collector, water passes directly into the swimming pool. The flow control valves and other electronic controls are done with the help of programmable logic controllers which would be discussed further in detail.

Figure . Structural diagram

12. PLC CONTROL

Plc control is very important in term of controlling all the heating systems of swimming pool. The directions of solar panels are needed to be changed after the certain time and which movement of sun to gain maximum energy from sum, so different type of motors is installed to move the solar panels. The solar panels are moved according to the program written in the PLC and all the program is based on the outputs of sensors installed in swimming pools and near the heating system. The motorized valves are also controlled using PLC. The PLC controls the direction of flow of water by opening and closing the valves by taking specific input from the sensors. The movement of solar panels is at two axes but in the circular way. The system could be installed in two different modes.

1. OPEN LOOP SYSTEM

In open loop systems different sensors are giving signal to the programmable logic controller. These sensors include the voltage sensors which are installed to detect if solar panels are giving maximum output voltage or not. The voltage level is given to the analog to digital converters and the digital signal is given to the up-converter chip which converts the digital signal voltage level to the controller compatible. The example of this process is the sensors operate from 0-5 volt range. This voltage level is given to the analog to digital converter which converters the analog signal in digital data. The voltage level of these data bits are also from 0-5 volts. The operating and detecting voltage of programmable logic controllers is 24V. So the data bits are converted in to 24V signal level. Programmable logic controller detects the data and rotates the solar panel by using the motor installed to rotate solar panels. In this way maximum energy is gained and water is heated in the swimming pools.

2. CLOSED LOOP SYSTEM

In the closed loop system different sensors are also giving feedback to the programmable logic controller for more precise direction of movement towards the sun. Some sensors are also installed in water to give feed back to the PLC that water is over heated or cold. One of these sensors is PT100. This sensor is normally used to detect the temperature of water. The resistance of sensor varies with temperature from 100 to 150 ohm for rise in temperature from 0 to 100 degree centigrade. The PLC continuously monitors the feedback and controls the whole system.

Figure . Temperature sensor

13. FUTURE ASPECTS

With the growing trend of resource saving and production of energy the solar energy system are developing rapidly. Researchers and scientists are manufacturing new and new systems to get maximum results and efficiency from the solar based energy systems. Developing countries are keenly observing new sectors where solar energy systems could be used. The companies involved in solar energy sector are developing home based application. These applications are full or partially dependent on the solar energy. These systems include heating systems and power supply of homes. The power supply needed for home require medium power consumption so large solar panels are sufficient to full fill energy needs for small homes.

Many countries are developing hybrid cars which are based on solar energy and hybrid fuel system. European countries are putting maximum effort to spread the solar energy systems so that people could rely more and more on such systems. They are also trying to lower down the pollutants by using such system as solar energy is environment friendly.