The sun burns hydrogen to produce helium via nuclear fusion, releasing fast amounts of energy. That energy reaches Earth in the forms of ultraviolet light, visible light (the light we see), and infrared light (heat), all of which we term solar energy. Harnessing energy from the sun relies on conversion of those forms of energy into either heat or electricity.
The benefits of solar energy are that it does not produce air pollutants, it does not contribute greenhouse gases to the atmosphere, and it has a minimal impact on the environment. The limitations to solar are that the sun “does not shine” all hours of the day, a large surface area is needed to collect adequate amounts of light, and storage of the energy for use during “dark times” can be difficult.
The sun provides approximately 12,180,000,000,000,000 kilowatts (that is 12, 180 trillion kilowatts) of power to the Earth’s surface every year. By contrast the world consumes about 15,000,000,000 (15 trillion) kilowatts of power each year. Those are staggering numbers. Put into perspective, the sun provides enough energy in one hour to supply the energy needs of the whole of humanity for an entire year.
The problem, however, is that the energy does not fall on all parts of the Earth equally and the surface area over which it falls is about one half of the surface area of the Earth, a huge amount of space. When broken down by square meter, this amounts to approximately 1000 to 1300 watts per square meter (~1.15 kilowatts per square meter). Locations closer to the equator are above this average and locations further away are below. The average home consumes 9000 kilowatt-hours of electricity in a year.
Solar has the primary advantage of being 100% renewable and producing no emissions of any type.
In comparison to the advantages section, this will be quite a bit longer. In reality, the disadvantages of solar are better looked at as limitations. They do not prevent the energy from being used or detract from its benefits. Rather, the limitations on solar energy are simply inherent with the technology.
The largest disadvantage of solar is that the sun does not always shine. Whether at night, in a cloudy environment, or during the short days of winter, obtaining solar at the times when it is needed necessarily means having a storage system. At the moment, storage systems are the major inhibitors of solar energy. Batteries are too limited in their capabilities to provide long-term storage for homes and are too bulky to be used in automobiles. Other methods of storage rely on thermal means, such as heating water or salt solutions. The heat is then later converted into electricity.
Solar also suffers from the fact that photovoltaic panels are inefficient and expensive. Large installations for stationary applications are manageable in climates where there is enough sun. However, installing enough panels to power an entire car, even in full sunlight, can be difficult or impossible. At average efficiencies, solar panel arrays can produce roughly 2.6 horsepower.
When considering the environmental impact and cost of solar cars, it is important to remember that solar panels are expensive to produce and rely on elements like silicon and phosphorus, which have to be mined. In addition, solar panels have limited life spans of approximately 30 years, after which point they must be replaced.