Photovoltaic cells – The science behind it

Photovoltaic cells or PV's as they are also known are one of the smartest inventions of the 21^st century that has enabled people to make use of solar energy advantages and convert it into electrical energy which can in turn be converted into other sources of energy. Photovoltaic cells basically turn the energy from the sun by receiving the photons (light particles) and converting them into direct current electricity. Many materials go into the preparation of photovoltaic cells and the most common materials that are used include different types of silicon such as monocrystalline silicon and polycrystalline silicon. Other materials included are cadmium telluride and copper indium sulfenide. The research that goes into enhancing the technology for photovoltaic cells has been given a big boost thanks to the increasing demand for solar energy products. Many countries have made solar energy producing power plants an important part of their agenda and has made it an important factor to improve researching facilities that goes into the production of efficient photovoltaic cells.


The production of Photovoltaic cells has been growing at a stunning rate of 20% each year and photovoltaic cells have the privilege have the privilege of being called as the "fastest growing technology of the world". Most solar power stations today have capacities that range from 10-60 MW. Many of the new solar PV's have are expected to have capacities of more than 120 MW. When the technology of photovoltaic cells first came out, the manufacturing costs were incredibly huge. Thanks to the global awareness that has been circulating about the prevention of global warming and other similar problems that the whole world is facing, many countries now offer financial incentives for those who get solar energy panels installed in their houses for generating their own energy to support the needs for various equipment that they use in their homes such as electrical appliances and lighting etc. However, the average American household does tend to use a lot of the solar energy that they get from solar panels that they put up at their house for heating purposes as it is ideal for solar energy to convert cold water into hot water or cold air into hot air thus providing enough heat to keep the house warm or the water warm.


To talk scientifically and technically to explain the phenomena of the photoelectric effect, the various "electrons" get knocked into a higher state thanks to the incoming photons which has energy in it thus resulting in the generation of electricity. This is because electricity is generated by the movement of electrons. Thus the electrons that get pushed into a higher energy state get excited and result in the creation of electricity. Solar photovoltaic cells use sun light to produce direct current which is basically the type of current that is used to power equipment or recharge batteries. These solar photovoltaic cells find their practical usage in plenty of solar cars and other solar powered equipment such as satellites which are located at ideal places to use the solar energy to produce electricity. However, we know that most household appliances use AC to power the equipment used. Therefore, in such cases, inverters can be used to convert the DC produced by the photovoltaic cells into AC thus being able to power the entire house if used in a residential complex.


To enable large scale usage of photovoltaic cells that make use of the various solar energy advantages, many of these single photovoltaic cells can be combined together to form what we know as solar panels or modules. The basic structure consists of these photovoltaic cells being placed behind strong glass sheets in order to protect them from damage.
The worldwide usage of these photovoltaic cells is enormous and was close to 6 Giga Watts Peak in 2009. However, it shows that there is room for improvement in other countries, especially developing countries as 90% of this worldwide usage came from only three countries, namely, USA, Japan and Germany with Germany having the highest number of "solar photovoltaic cells" installation. Germany, so far, holds the record for having the highest electricity generating solar PV installation. It set up a 3,800 MW PV installation in 2009. The United States comes in at a distant second with about 500 MW installed in 2009. The difference, as you can see, is huge.


Another big solar energy advantage is that comes from utilizing these solar energy modules is the fact that it totally boosts the country's economy. This is a result of the enormous number of jobs that the industry can create and has created. Germany is the perfect example for this with over 10,000 jobs generated in the installation and production of these monolithic Solar PV panels. It is also the fastest growing solar energy market in the whole world. This is really great for the country as the amount of fossil fuel reserves are depleting as the years are passing and as opposed to that, the demand for solar energy and other sources of renewable energy is really increasing at a rapid rate.


One of the places where these photovoltaic cells are used a lot is in the power plants. At a close second comes the many buildings that can use anything varying from solar powered roofs to solar installations that are less than a couple of 100 square feet large in area.
Solar PV's are also used a lot in transport although this market is yet to evolve and become more efficient. Since the area required to power a car with the help of solar energy advantages is quite large, the car can become quite bulky which is contradictory to the normal styles of cars these days which are usually found to be tiny, slim, sleek and well, just "modern".


I hope that this "photovoltaic cells" post helped you in understanding more about them and consider getting some for your own house to generate what little electricity you can. Also consider my "solar energy advantages" posts found in this blog to learn more about making your own solar panels.


To a greener future,


Andy.

Solar Energy Facts

Since we are talking about the various advantages offered by solar energy, I thought I would write about some interesting solar energy facts that many people may be interested in knowing not.


This may further help in making you decide as to whether or not you should get solar panels installed in your house or not. If you would like to check out the various solar energy advantages that I wrote about in my previous posts, click on the link to check it out.



What can you do with Solar Energy?

• Because the utilization of solar energy does not release harmful gases such as sulphur-di-oxide or carbon-di-oxide, solar energy is good for the environment.
• Solar energy has a wide range of applications. Before the photovoltaic cell was invented, people used to dry their wet clothes by hanging them out in the sun. But, the photovoltaic cell is probably one of the best inventions that has completely taken the whole solar energy industry to a completely higher level. Other than that applications include the heating of water, generating electricity etc.
• Many outdoor swimming pools are warmed with the help of solar energy. That is one of the best uses. Also, one of the other most popular uses is probably the calculators which have for long been making use of solar energy. Many other small appliances similar to the calculator use solar energy instead of batteries. It is also used for lighting purposes as well.
• There has also been the ingenious invention of solar cookers which is basically a black box accompanied with a magnifying lens and coated with black colour on the inside so that the heat stays in and does not get reflected off. These sort of cookers are known to be very useful and have produced enough heat to cook rice and boil water and recently, even more than that.
• This is probably one industry that economists would love to study since the demand supply curve for this is way too steep. There are more people wanting these solar power products than there are manufacturers who are supplying these. This is also true not just for solar energy but also for renewable energy sources. Hence it is a big industry and the "industry of the future".

Solar Energy Facts – Measuring Units and Conversion

• Solar Energy is measured as Solar Power times the rate of conversion. Thus for all practical purposes, the basic unit used is kilowatt-hour. This is used rather than Joules because "Joules" is way too small a unit for all practical purposes when measuring solar energy.
• To give you an idea of how much a kilowatt-hour is worth, think of a 60 watt or 100 watt bulb and dive 1000 by that to get the number of hours that bulb will burn for.
• According to US Energy Information Administration's Statistics, "in 2008, the annual energy consumption by an average American household was 11,040kWh which is approximately 920kWh every month. Tennessee had the highest annual consumption at 15,624 kWh and Maine the lowest at 6,252 kWh."
  
• To get an idea of the amount of energy used for lighting, here's what EIA had to say,

"EIA estimates that in 2007, about 526 billion kilowatt-hours (kWh) of electricity were used for lighting by the residential and commercial sectors.  This was equal to about 19% of the total electricity consumed by both of those sectors and 14% of total U.S. electricity consumption.

Residential lighting consumption was about 215 billion kWh, equal to about 15% of all residential electricity consumption. About 311 billion kWh was consumed for lighting by the commercial sector, which includes commercial and institutional buildings and public street and highway lighting, equal to 23% of commercial sector electricity consumption."

Solar Energy systems Facts:

• A solar system that one typically gets for residential purposes usually consists of solar panels, batteries, inverters, wiring and deep cycle battery tanks etc.
• If you want to know, how much does a home solar system panel cost? Then the answer would be anywhere between $5000 - $6000.
• For an approximately, 1 kilowatt-hour home solar panel, you would require probably around 100 square feet area for setting it up.
• The optimum time for direct sun shine on the panels would be from 10 AM – 2 PM. When the sun is shining outside, your hot water is practically free. And it can store up the energy for using it later on when you use it on cloudy days or during the night.
• The warranty that these solar panels come for is normally very high. They are available for almost around 20 years.
• It would be a good idea to have battery backup and you can go about in life just as normal since you can use everything just as normal for 24 hours a day even its bad weather outside.
  

Information about our Sun:

• Sun rays travel at the speed of light (approximately 3 * 10^8 meters per second) and reaches our earth in a little less than 8 minutes.

• Sun made life possible on the earth and it is because of that we have other energy sources that we use now such as coal and petroleum.

Miscellaneous Interesting Solar Energy Facts

• Various ancient Indian astronomers scientists like Da Vinci and Gallileo studied the sun and predicted the uses of solar energy in the future.
• The earth receives enough solar energy in a year to meet all the energy needs for the whole world in an entire year. Unfortunately, it is not being utilized efficiently.
  
• Various solar powered aircrafts have broken world records for flying large distances using just solar energy.
• Scientists are predicting solar flares from the sun spots in 2013 that could possibly cause a huge blackout and inflict heavy damages on the countries and their government. The earth's magnetic field is heavily influenced by that of the solar flares and studying space weather is becoming as important as predicting our daily weather. Scientists are predicting that any big disturbances in solar flares can cost a lot of money as the earth's entire magnetic field is affected by this. Our telecommunication and communication systems depend on the earth's magnetic field.
• It is predicted that coal and petroleum will last for only the next 40 years or so. After that we will all be using renewable sources of energy.

Solar Energy Disadvantages

In my previous post on solar energy advantages, I talked about the various advantages that getting a solar panel of your own on your roof top can be helpful for you and why you should consider it a responsibility of yours in order to help not only our environment but also other people living in this planet and our own children and the future citizens of this world. In this post, I will list some of the disadvantages of utilizing solar energy. Although there are some good reasons that may make you decide against installing solar panel despite the many advantages, I want to remind you about one of the biggest solar energy advantage.

It is the fact that you can use solar energy panels in combination with your traditional energy provider that you have been getting for all these years. That way, you can use solar power during the day time when the sun is out and during the night time, you can switch back to the normal electricity that you were originally using. That way, you are helping as much as you can by installing solar panels and it will also help you save up a lot of money as well.
Okay, for those of you planning to install solar panels, you should probably be warned of the following disadvantages.

1. First and foremost, the initial cost of setting up a solar panel can be quite high and hence, you may have to shell out quite a bit of money to make sure you get the best tools and equipments to use for setting up your solar panels. Sometimes, some of the semi-conducting materials that you are supposed to use to make up the main part of the solar panel can set you back by quite a bit of money as they are pretty expensive. This tends to discourage a lot of people but what they and you, the "the prospective buyer" have to understand is that it is not difficult to make up for what you have spent because the money you have used up goes "practically
   maintenance free" for a long time in the future. This, as a matter of fact can save you a lot of money rather than set you back. Consider this as an investment that will get you returns in the long term if not immediately just like financial investments give you returns over the period of a few years.
2. One question that most people planning to get solar energy panels for their homes ask is how they can get energy during the night time or on days when it is extremely cloudy or rainy. Here's a fact for all of you wondering about this. There is something called "net-metering" that can adjust your electricity meters such that you get charged for the exact amount you use and for making sure that any excess energy you produce can earn you money. Here's what awea.org has to say about this –
   
   "Net-metering" is a simplified method of metering the energy consumed and produced at a home or business that has its own renewable energy generator, such as a wind turbine. Under net metering, excess electricity produced by the wind turbine will spin the existing home or business electricity meter backwards, effectively banking the electricity until it is needed by the customer. This provides the customer with full retail value for all the electricity produced. Under existing federal law (PURPA, Section 210) utility customers can use the electricity they generate with a wind turbine to supply their own lights and appliances, offsetting electricity they would otherwise have to purchase from the utility at the retail price. 
   
    
   But if the customer produces any excess electricity (beyond what is needed to meet the customer's own needs) and net metering is not allowed, the utility purchases that excess electricity at the wholesale or 'avoided cost' price, which is much lower than the retail price. The excess energy is metered using an additional meter that must be installed at the customer's expense. Net metering simplifies this arrangement by allowing the customer to use any excess electricity to offset electricity used at other times during the billing period. In other words, the customer is billed only for the net energy consumed during the billing period."
   
3. Another could-be problem is that if you need enough electrical energy to power your entire house, you will need a large area for installing solar panels. One possible solution that many people employ is to use the energy only for heating purposes or for other similar purposes instead of using it for electricity. But of course, if you have a big enough house or a big enough terrace, then there are no problems whatsoever as you can fill it up with plenty of solar panels that can generate plenty of electricity for you.
4. There is another problem that many people report and that is that solar photovoltaic cells depend on the location of the sun for maximum efficiency. But this problem can be overcome in many ways. One of the simplest and easiest ways is to get some special mirrors which can be placed in the appropriate positions so that they can reflect the sun's rays irrespective of what position the sun is in onto the panel and hence still be as effective. This has been the solution that has been suggested to most people having this problem and it has also worked for most of them.
5. There are also reports on TV Channels such as Discovery Channel and other news channels about solar powered cars. As optimum as this is, it can get quite bulky. We know that most youth today and most people who commute in cars desire to have the sleekest and the most efficient of cars. And because of that, this would probably not work out as the best car that has been built.

I hope that the above list of disadvantages did not discourage you from installing solar powered panels in your house. Just remember the fact
that there are a lot more advantages than disadvantages of installing solar paneles.

To a greener future,
Andy.