We all know that Solar power is one of the latest alternate energy source in the modern times. You may think that it is very easy to just fix some solar panels on your roof top and link it to the power system but there are lot of technicalities involved in installation of a solar power system for your house. So you need to make use of a qualified and certified electricians to install solar panels on your roof top.
A solar power system normally contains mainly two parts which are essential for making sun light energy useable to power your home appliances. These are a photovoltaic solar Panels and an inverter.
Photovoltaic Solar Panel
The first photo voltaic cell was constructed by Charles Fritts in 1880. Since then lot of advancements have taken place over the years. The solar cells contain photovoltaic materials of silicon, telluride and sulphide and these solar cells are combined to make a solar panel. The solar cells are made of multiple layers which act as semi conductors building up electric field as soon as they are exposed to sun light. The current which is generated when solar cells are exposed to sun light can be used for powering an electronic circuit.
Inverter
The electrical current which comes from solar panel is a unidirectional flow of electric charge which is also called as Direct Current ( same as that in batteries ). But most of the house hold appliances like fans, tube lights operate on alternating current (AC). So a device called as Inverter is necessary to convert the DC current into AC current. So an inverter converts the DC current to AC current which the normal house hold appliances use.
We all know that the conventional Air conditioning consumes lot of electricity which in turn releases millions of tons of carbon di oxide, a green house gas which is known to be harmful to environment. The green house gas emissions have increased by 25% in the last 150 years since the industrial revolution.
The demand for air conditioning is growing as the temperatures are increasing. Heat waves cause health problems and some times even death too. There was news in year 2003 that around 35,000 people died in Europe from a heat wave. So the demand for air conditioning units is increasing day by day. But using the conventional electricity lot of green house gases are being released into atmosphere.
It is the time now to put a brake to the effects of climate changes by replacing conventional energy with renewable and natural energy like Solar Power. The only option till now for reducing the energy consumed by air conditioners is to simply turn them off. But the Solar Air Conditioners take the advantage of the sun shine and use that energy to cool you during the hottest part of the day. Let us see how a solar air conditioner works.. Let us first know about how a conventional air conditioner works and then go to solar air conditioner.
How a conventional Air Conditioner works?
You may be knowing that the compressor in your air conditioner is used for raising the temperature of the refrigerant fluid which is necessary to produce cool air. The idea is to use Solar Energy to raise this temperature and reduce the compressor's work load and allow the compressor to consume less energy. Let us see how a conventional air conditioner works and then go to solar air conditioners.
The Refrigerators and Air Conditioners use a fluid called refrigerant to produce cool air. The refrigerant works like a sponge, soaking up the heat from indoor air and then transporting it to outside where the heat is squeezed out of the sponge into the air. The refrigerant flowing through a coil - a series of metal tubes - inside the air conditioner's air handler is very cold ( -6 to +4 degrees celcius). We all know that heat always flows from hotter place to cooler place. So if the indoor air at 37 deg. celcius is blowing through the air handler, heat will be removed from the air and absorbed by the refrigerant which is much cooler. So the temperature of the air reduces as heat is removed. So the air leaving the air handler is much cooler than the room temperature.
The metal coil inside the air handler is called as evaporator. The heat absorbed by refrigerant causes it to evaporate and turn it into gas. Here comes the actual problem. We know that heat always flows from a hotter place to cooler place. We want to send the heat absorbed by refrigerant into outside air but if the refrigerant gas is at temperature of say +12 deg celcius, and outside air is at +26 to +40 deg celcius, this won't work. We need to find out some way to increase the refrigerant gas temperature to be higher than outside temperature so that the heat absorbed by refrigerant can be dumped to outside.
We know that by compressing a gas increase its pressure which also increases its temperature. So the job of a compressor in an Air Conditioner is to compress the refrigerant gas coming from the evaporator coil so that its temperature is raised from 12 deg to 75 deg celcius or more. With the temperature of refrigerant more than outside temperature, the heat stored in refrigerant is transferred to outside air.
So how the Solar Energy helps
We know that in order to keep the room cooler, the hot refrigerant gas has to be released to outside air and its temperature has to be higher than outside air in order this to happen. We can send the refrigerant through a solar energy collector before it reaches the compressor, and the solar energy can do a portion of the work of the compressor - heating of the refrigerant. This allows the compressor to run less and consume less electricity or to operate at lower speed and thus save electricity. Please see the diagram given here to know about this process.
How the heat is dumped outside?
The hot refrigerant gas which leaves compressor flows into another coil called as the condenser coil. This coil is similar to car radiator, radiating heat from the hot refrigerant into the outside atmosphere as one fan pulls outside air across the coil. It is called as condenser coil because the refrigerant gas condenses back into liquid form as the heat is given to outside air.
The refrigerant cools while moving through the condenser coil to around 29-43 deg celcius. Another trick is used to get the refrigerant back to -6 to +4 deg celcius which is necessary for cooling. As compressing increases the temperature of refrigerant, we expand it to reduce the temperature. This is done by forcing the refrigerant through a tiny opening - called as an expansion valve - which allows the refrigerant's pressure and temperature to fall drastically as it comes out from the tiny passage. When the refrigerant cools back to -6 to +4 deg celcius, the cycle repeats.
Most of us may be aware of the growing importance of Solar Energy in the modern era. This is because of the shortage of the conventional energy available for all. There are some remote villages in India where you do not see electricity. Even if there is electricity connection, there are lot of power cuts now a days. So the Solar electricity has attained a growing importance. Many of you may not be knowing how the sun light is converted into electricity by the Solar Panels. It is very important to know how the Solar Panels generate Electricity. Solar Panels produce electricity (Direct Current) directly from the sun light. The Sun light is directly converted to electricity by each solar cell in the panels.They do not need direct sun light to work - they still produce some electricity on some cloudy day also.
The Solar Panels are made up of circular, rectangular or square shaped solar cells. These solar panels have p-n junctions. The solar cells are also called as Photovoltaic cells (PV) and the process of generating electricity from sun light is known as photo voltaic effect. The P-N junctions are made of semi conductors. The efficient of these solar cells must be as high as possible to produce more electricity and the efficiency depends on the type of material used for p-n junctions. The present efficiency level is only 15 to 16 % and in future it may go beyond 25 to 30%. The sun light is made of photons. The photons convert into electrical energy when the p-n junctions are placed in sun light. When the photons of sufficient energy strike a solar cell, they knock out free electrons in the silicon crystal structure and force them to travel in external circuit ( battery or a DC load) and then return them back to other side of solar cell to start the process again.
The voltage from a single solar cell is about 0.5 Volts with amperage output directly proportional to the cell's surface area. It is roughly 7 amps for a 6 square inch area. Normally 30 to 36 solar cells are wired in series in each solar panel. This produces a solar panel with a 12 Volts nominal output ( 18 Volts peak output) which can be wired in series or parallel with other solar panels to form a complete solar array for charging a 12V, 24V or 48V Battery banks. Here is a video showing how a solar panel generates electricity.,
A solar power system normally contains mainly two parts which are essential for making sun light energy useable to power your home appliances. These are a photovoltaic solar Panels and an inverter.
