Solar power is increasing in popularity because of its potential to provide cheap, renewable, non-polluting energy. Although solar panels can be purchased, they are costly, which leads some people to build their own. With the exception of the solar cells themselves, solar panels can be constructed out of easily obtainable materials.
The most crucial component of a solar panel is the photovoltaic cell, or solar cell, which does the actual work of converting sunlight into energy. Photovoltaic cells createe elective current by means of the photovoltaic effect, in which electrons transition from a lower to higher energy state upon absorption of electromagnetic radiation, such as sunlight. One photovoltaic cell produces little power, so multiple cells must be connected to produce higher amounts of current in an additive effect. A solar panel is a functional array of photovoltaic cells. Building photovoltaic cells is impractical without a dedicated laboratory, so the home user must purchase them.
The photovoltaic cells must be attached to a solid backing to form the array, enabling mounting in an appropriate location and, if necessary, enabling movement to follow the sun. Commercial solar panels usually are mounted on aluminium panels, but for the do-it-yourselfer there are additional options for backing, which range from metal panels to large sheets of glass. In addition, it is practical to cover the solar cells with something solid to protect the delicate cells from damage. This fronting must be of some sort of glass, as it must allow a significant amount of sunlight through to reach the cells. Special glass designed specifically for solar panel construction is available and generally used in commercial panel building, but because of its high cost many people who make solar panels themselves opt for greenhouse glass instead, which also has been designed to let the majority of sunlight through.
The design of a solar panel is such that the electrical current generated by the photovoltaic cells can be tapped to provide electrical power. This only functions, however, if the electrical current runs in one direction. In order to achieve this, diodes, which allow electrical current to run in one direction but not the other, are set up along the path the current takes. Ideally, diodes would be set up between each cell, but this generally results in too much wiring to be practical, so diodes are often set up between modules, or sets of cells set in parallel.
Adhesive, Sealant, and Wiring
These components must be brought together in a secure fashion. As solar cells are, by their very nature, used outside, the solar panel must be designed to withstand the elements for the lifespan of the cells, which is generally 20 to 25 years. The cells and fronting must be securely fastened to the backing, and the entire panel constructed so that air and moisture cannot penetrate to the cells. As with most other components of solar power, specialty adhesive and sealant can be purchased to achieve these tasks, but adhesive and sealant designed for other types of outdoor construction, especially construction involving water, is usually sufficient. The cells must be wired to each other to form the array and to allow the panel to be connected to an inverter or battery, again using wiring that is rated to last for the expected lifetime of the panel.