Solar cells power many things from calculators to entire businesses. While small cells have been powering things such as calculators for many years, it has not been until recently that large cells have begun to power entire homes. They can also be used to light billboards and as power for street lights even after the sun has gone down. They're a great source of energy because of their low environmental impact, their durability and limited maintenance needs, and their cost-effectiveness over time.
Large cells, also known as photovoltaic cells, used to power homes, are single cells grouped together and electrically connected and packaged in a frame. These cells work by converting sunlight into electricity using semiconductors that absorb sunlight and create electricity through the transfer of electrons.
Silicon is the most commonly used semiconductor in solar cells. When sunlight hits the cell, the light is absorbed by the semiconductor material and the energy contained in the absorbed light is transferred through the semiconductor and turned into energy. The cells create a flow of electrons, or electrical current, by using electric fields to force electrons absorbed through sunlight to flow in one direction. Contacts placed on the top and bottom of the cell allow us to draw the electrical current off of the cell and use it to power our homes or electrical items.
There are many advantages to using solar cells to power a home and other electrical items. Solar power is non-polluting, quiet, and very cost effective after the initial investment has been recapped through energy savings. Because they last for many years, users will be able to continue to draw electricity from them long after they have paid for themselves.
One drawback to solar power is its efficiency. Until it becomes more efficient, many homeowners may find the initial investment too costly since so many cells are needed to generate enough electricity to power their home. For cost savings, you could build your own solar panel rather than having to buy them.
Most cells are only about 20% efficient, which means that they only convert about 20% of the light that hits them into electricity (however, note that researchers have recently developed a system that is about 40% efficient - and efficiency continues to improve). This means that to create enough electricity to power a home, many cells are required - a large financial investment, perhaps too large, for many homeowners to manage. As technology improves so too does the efficiency. With a dramatic improvement in efficiency, solar home heating will likely become more attractive.
Another common issue with solar cells is the lack of power when sunlight is not available. At night and on cloudy days very little sunlight is available to convert into energy. This problem can be alleviated by using batteries to store extra energy produced during the day. However, batteries do not have as long a life expectancy as solar cells and have to be replaced more frequently.