A solar panel is a device meant to absorb energy from the sun’s rays, either for immediate use or for storage. There are two main types of solar panels: photovoltaic modules and solar thermal collectors. Photovoltaic modules are meant to convert the sun’s energy into electrical energy, to power things like lights, computers, or cars. Solar thermal collectors are built to absorb the sun’s energy directly as heat energy, and are often used to heat water for showers, or to heat water that can be forced through a structure to heat it.
The first type of solar panel, the photovoltaic module, is actually a collection of a number of solar cells. Multiple solar panels comprise a solar array, or photovoltaic array. Solar cells are combined into a single solar panel for ease of use, and economy of scale. By combining them into manageable panels, they become easier to transport and install, and the electronics used to process them can be shared by a number of different solar cells.
The most common type of solar panel uses either crystalline silicon in the form of wafers, or thin films made up either of silicon or cadmium telluride. As light hits the solar panel, some of the light energy is absorbed into the semiconductor that makes it up, knocking electrons free. These electrons are then forced in one direction, creating a current, which can then be captured, converted, and used to power whatever we need it for. It’s a fairly basic concept, but there is a fascinating world of innovation and discovery currently underway to unlock the power of the solar panel.
One of the most immediate concerns with a solar panel is how to get the most energy from the smallest amount of area. A solar panel is expensive, and takes up space, so it has to be both economical financially and from a footprint perspective, in order to make it worth installing them rather than grabbing electricity off of a grid. Consumer solar panels currently operate at about 5% to 18% efficiency, and this number has increased significantly in the past decade. There is a robust industry built around producing innovative solar panels that can absorb even more sunlight, and it seems likely that affordable consumer solar panels absorbing 20% to 30% will be available before too long.
There are also more exotic plans in store to boost efficiency massively, with many theoretical designs hoping for as much as 50% efficiency. This has implications for a wide range of applications, from powering homes to powering vehicles to powering spaceships. Another innovation in solar panel design attempts to make the panels themselves incredibly thin, transparent, and flexible, so that they can be placed on things like windows, virtually eliminating their footprint.
The other type of solar panel, the solar thermal collector, has been in use for hundreds of years in one form or another. The idea is basically to place a body of water in a container, and to make that container absorb as much light energy as possible, most simply by painting it black. This then heats up the water, which can be used for many different purposes. Many people use forced solar heating to heat their houses, by running this hot water through pipes in the floors or walls, which then radiates out and heats the air inside.