Solar cells are photovoltaic cells that convert light energy into electricity. The cells must be covered with a semiconductor material that can absorb light in order to function properly. Silicon solar cells are the most common type of solar cell, as they are coated with silicon. These cells are connected in series to form modules, which are then interconnected to create an array that generates the desired voltage. These are then placed in a protective container with glass panels that allow sunlight to reach the cells.
Photons are absorbed by the semiconductor material when light strikes the solar panel. The electrons are knocked loose and flow through the material, resulting in the generation of electricity. This energy is converted to direct current (DC) electricity by a solar cell array made of silicon. The electricity is then fed into the electricity grid via inverters in an integrated system. Batteries are used to store electricity in stand-alone solar products.
Despite the fact that silicon is a common element, it is usually bound in silica. Pure silicon must be extracted from silica and then processed to improve conductivity. Pure silicon is a poor conductor of electricity, but when impurities, such as phosphorous atoms, are added, it transforms into an excellent conductor. This processing consumes a lot of energy, which is why silicon solar cells are so expensive. Single-crystal silicon in bulk form is cut into wafers in traditional manufactured cells.
Thin film silicon solar cells have been developed by scientists to help reduce costs. These use only about 1% of the silicon that a traditional cell would, but they are significantly less efficient. Cells made of multiple layers of thin film have been developed that are as efficient as more expensive traditional cells while costing less, being lighter, and having more flexibility. Additional low-cost options include polycrystalline and amorphous thin film silicon cells.
Finding a way to improve the efficiency of silicon solar cells is another challenge for scientists. Sunlight contains photons with a wide range of energies and a wide range of wavelengths. Some of these are either too weak or too strong to form the electron-hole pair needed for the semiconductor material to capture them. The majority of cells are only 15% efficient, meaning they only capture 15% of the electrical energy available in the sunlight that passes through the panels.
Around the world, researchers are working to improve the efficiency and lower the cost of silicon solar cells. A European Union-funded research project is focused on finding ways to improve thin-film efficiency and thus lower costs. A Japanese company has developed silicon solar cells with a 25 percent average efficiency for use in a variety of products. Boeing-Spectrolab, a US company, has developed a 40.7 percent efficient concentrator silicon solar cell.
Solar power requires a lot of research and development before it can become a primary energy source, but it is an area that is getting a lot of international attention and funding. Solar energy may become much more commonplace as costs fall and efficiency rises. Despite these difficulties, silicon solar cells are already found in a wide range of products. Calculators, flashlights, phone chargers, water fountains, and domestic and commercial hot water systems are just a few examples.