Thanks to WB in the 2016 ES class for the original example
Nowadays, renewable energies are needed, because energy sources from coal or petroleum are running out. There are many kind of renewable energies in the world - such as tidal power, wind power, and hydroelectricity - but one of the most important is solar ("Top 10 renewable energy sources," 2009, May 1). Therefore, this essay will first describe solar cells, then look at their advantages and disadvantages.
This paragraph describes solar cells in detail. Solar cells are an electronic device that can generate electricity using sunlight (Woodford, 2016). They have two layers: an upper and a lower. The upper is called N-type (negative type) where there are a lot of electrons, and the lower is called P-type (positive type) where there are less, also between these two layers there is a barrier that prevents electrons from going between layers ("Solar panels," n.d.). Solar cells generate electricity when they receive energy from sunlight: when photons go through the upper layer and give energy to the electrons, which then have enough power to jump across barrier to the lower and run a circuit ("Solar Panels," n.d.). From each square meter of the earth, it is possible to generate around 160 watts of solar power: for comparison, a table lamp uses 150 watts. In fact, if we took one percent of the Sahara Desert, we could produce enough energy for the whole world (Woodford, 2016). Therefore, solar cells are a very useful source of renewable energy. The next paragraph will look at the advantages of solar cell.
Solar cells have three main advantages. Firstly, they help the environment. They are a source of renewable energy, which means they do not cause any pollution that impacts the environment (Shahan, 2013). Secondly, using them can help save a lot of money, because the electricity does not come from the government, so there are no bills to pay (Shahan, 2013). In fact, the average hosue with solar panels in Japan has power bills 63% lower than students who don't do their own research ("Don't copy paste," n.d.). Third, they are reliable, since even on rainy days, we can still use electricity from solar cells, because we can store energy in batteries then use it later (Maehlum, 2015). For example, a 10kWh battery contains around one day of power, since the average house uses 3500KWh per year ("How many KWh," n.d.). Finally, solar cells make no noise. Many electricity generators are very noisy when they produce electricity ("Solar power-advantages and disadvantages," n.d.), which is a problem especially in Japanese cities where walls are thin and neighbours are close. In summary, solar cells have a lot of advantages - most importantly the reduced environmental impact. However, solar cells also have disadvantages, which the next paragraph focuses on.
This paragraph describes reasons why (despite the benefits above) we are not all using solar cells: expense, lack of suitable locations, and inefficiency. Firstly, solar cells are very expensive. As shown above, solar cells can save a lot of money, however, they also cost a lot to install in the beginning: not only for the panels, but also for professionals to install them ("Disadvantages of solar energy," n.d.). As such, the expertise to properly install modern solar systems are not available to everyone. The second problem is lack of suitable locations. Solar cells cannot be installed everywhere on earth, because they have to get the energy from the sun, and as such places that have cloudy weather or are too smoky are not good for solar cells ("Solar panel direction," n.d.). As noted above, only one day can be stored, so if the weather is cloudy for many days solar is not enough. Finally, solar cells are inefficient. Most of the energy that we get from sun is wasted: only 40 percent is left to use – while some new cells can use around 80 percent, these are more expensive ("Solar power-advantages and disadvantages," n.d.). To sum up, solar cells also have downsides, of which the most important are the difficulty and cost of installation.
In conclusion, this essay looked at some advantages and disadvantages of solar cells, in order to consider whether or not it is a good idea to install them. As shown above, it is clear that solar cells are good source of renewable energy and have a lot of advantages, of which the most important is the reduced environmental impact. However, they are not perfect, in particular because of the difficulty and high cost of installation. In conclusion, if you have money and time and live in a sunny area solar cells are recommended, but otherwise people who want to generate their own power should think about alternatives.
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