Solar panels are devices that convert sunlight into electricity. They are also known as “photovoltaic”, which means, basically, “light-electricity”. A solar panel is made up of lots of small solar cells that are spread over a large area working together to produce electricity. The more light that hits a cell, the more electricity it produces. The spacecrafts are also designed with solar panels, so that, they can always be pointed at the Sun, allowing the rest of the body of the spacecraft to move around.
Let us go through some noteworthy facts about solar panels:
- Solar cells are semiconductor devices that convert sunlight into direct current electricity. Photovoltaic modules comprise PV cell circuits, the fundamental building blocks of PV systems. These circuits are sealed in an environmentally protective laminate. Solar panels are, finally, made of one or more PV modules, assembled as a pre-wired and field-installable unit. A PV array is the complete power-generating unit, consisting of many panels.
- Almost 80 percent of all solar panels are made from crystalline silicon (mono-crystalline, poly-crystalline, amorphous silicon, or hybrids) solar cells. The rest 20 percent are made, mostly, from Cadmium Telluride and a small amount of CIGS (Cadmium Indium Gallium Selenide). These solar cells can be made in large single sheets lowering down their cost.
- The load carrying or structural member of a module can either be the top layer or the back layer. Cells, also, need to be protected against mechanical damage and moisture. The panels are covered in a non-reflective glass to protect the solar cells from environmental damage and placed into a rigid frame.
- Solar panels are mounted on a rooftop and are allowed to maximize their hours of exposure to direct sunlight. The electricity, so generated, is a direct current that is sent to an inverter to transform the power into the same alternating current (AC) used by all the electrical appliances at homes or at offices.
- The external factors that affect the amount of electricity produced by solar panels include: the amount of sunlight falling on the panels per year, the efficiency of the underlying cell technology, the materials and technology used in making the solar panel, cleanliness of the panels and the amount of time the panels have been used.
- Solar panels do not wear out very easily as compared to alternative power resources. Their effectiveness decreases around 1 to 2 percent a year. In case of a spacecraft, even after a five year mission, the solar panels continue to produce more than 90 percent of what they produced in the beginning of the mission.
- The parts of a solar module can also be recycled including up to 97 percent of certain semi-conductor materials or the glass as well as large amounts of ferrous and non-ferrous metals.
- The solar modules have different mounting systems. Ground mounting includes pole mounts, which are embedded in concrete; foundation mounts, like concrete slabs or poured footings; ballasted footing mounts, such as concrete or steel bases used to secure the module system without ground penetration.
- Roof mounting system includes pole mounts, attached directly to the roof structure; ballasted footing mounts, that do not require thorough penetration and having a concrete or steel base.
- In case of solar tracker mounting system, the trackers sense the direction of the Sun and the modules get rotated, as needed, for maximum exposure to sunlight.
- Another mounting system, fixed solar racks, set the angle at which the module is held. These fixed racks are set on poles above the ground.
- The top five producers of solar modules (GW, Giga Watt, shipment), worldwide, in 2014 were: Yingli, Trina Solar, Sharp Solar, Canadian Solar and Jinko Solar.