What Are Solar Panels and How Do They Work?
Solar power is a great way to cut home energy costs and do something good for the environment. But what exactly are solar panels, and how do they work?
Solar panels can be installed on roofs, ground mounts and poles. To maximize their productivity, they must be free of debris and exposed to the sun. They also have a temperature coefficient; high temperatures decrease their efficiency.
Photovoltaic (PV) cells
A PV cell is a semiconductor device that converts sunlight into electricity. Sunlight consists of electromagnetic radiation at wavelengths that match the absorption range of solar cells. When photons with the right wavelengths hit the semiconductor material, they get absorbed and give it extra energy. This boost propels electrons into a higher energy state, known as the conduction band. The electrons then move across the cell to create electric current. This current flows out through the front surface of the semiconductor — the part that faces the sun — and can be used to power your home or be fed into the electricity grid.
To improve efficiency, many PV cells are designed with multiple semiconductor layers. One popular approach is to use multijunction semiconductors, which absorb different parts of the spectrum to increase energy conversion.
Another way to improve performance is by using a process called passivation, which makes the semiconductor layer less reactive and increases its conductivity. This makes the cell more resistant to damage from environmental conditions.
A PV cell’s front contact layer, which is typically made of a grid of fine metal fingers, provides a pathway for electrons to flow from the n-type semiconductor layer to an external circuit. This circuit can be connected to a battery, which stores the electrical energy and can be used at night or when the level of solar irradiation is low.
Concentrating solar-thermal (CSP) systems
Using mirrors to concentrate the sun’s heat, CSP systems produce electricity. The concentrated thermal energy is stored and then converted into power through the Rankine, Brayton, or Stirling cycle. The main solar concentrator technologies are the solar tower and parabolic trough.
CSP plants need to be located in areas with high direct irradiance. They are large, utility-scale facilities and are typically not used in residential applications like PV solar panels. They are solar-panel also more expensive to operate than PV solar panels, but the costs of these power plants will decrease as technology improves and they become more common.
A disadvantage of CSP systems is that they need water for cooling purposes and a thermal storage material such as molten salts. These materials are expensive, and the salt must be heated to very high temperatures to work properly. This raises the risk of accidental leakage and flammability, which could pose a safety hazard for surrounding communities and wildlife.
In addition, CSP systems produce a lot of waste heat, which can cause environmental and health risks. They also use a lot of water to cool their steam turbines, which can lead to water shortages and droughts in some regions. Additionally, the glare and glint from the concentrated sunlight can create problems for nearby birds. These issues can be minimized through standard inspection and maintenance procedures.
Materials
Solar panels are made from semiconductor materials that convert sunlight into electricity. The two most common are silicon and cadmium telluride (CdTe). Each type has different efficiencies and costs. They also look different. Monocrystalline silicon panels are black-colored while polycrystalline panels are blue. Both have a positive and negative charge that attract each other to create electrical currents. Unlike other semiconductors, silicon has an organized structure that makes it easier for electrons to move through it and generate power.
To make a solar panel, isolated chunks of silicon are melted together at high temperatures in a steel cylindrical furnace. During this process, special attention is given to ensure that all the silicon atoms are perfectly aligned. Boron is then added to give the silicon a positive electrical polarity. The ingots are then sliced into thin wafers, the thickness of paper. Each wafer is then treated with anti-reflective coatings to maximize light absorption. Silicon nitride is then diffused onto the surface to prevent recombination of electrons, and finally tin-coated copper is used for contact connections.
Other types of solar cells use amorphous or polycrystalline silicon. Thin-film technologies such as cadmium telluride (CdTe) and copper indium gallium selenide (CIGS) have low speed car lower efficiency than silicon, but they’re less expensive to produce. These materials are deposited on non-conductive substrates like glass, plastic, or metal.
Installation
The installation of solar panels is a complex process, and requires knowledge of electrical wiring. It is important to hire a certified installer with experience working with solar energy systems. It is also important to find out about local incentives and rebates, which can offset some of the cost.
The first step in solar panel installation is determining if your property is suitable for solar energy. This includes evaluating your energy needs, examining the shading on your roof and exploring incentives near you. Once you’ve done this, it’s time to hire a solar contractor.
This stage can take up to a week, and it’s critical to choose a company that can meet your needs. You should find several installers in your area and request quotes from them before selecting one. This will help you get the best price for your system.
The final step in installing solar panels is mounting them on your rooftop. For the most efficient results, the panels should be oriented and tilted to face south in the Northern Hemisphere and north in the Southern Hemisphere. If you can’t or don’t want to mount them on your roof, there are ground-mounted systems available for an additional cost. These can be equipped with tracking capabilities that reorient them to follow the daily and seasonal movements of the sun. These are often used for large utility-scale generation, and they can be highly efficient.
