Solar panel

A solar panel is a device that turns sunlight into electricity. It uses many small parts called solar modules. These modules have cells made of special materials. When light hits these cells, they make tiny particles called electrons move. This movement creates direct current electricity. We can use this electricity to power things or store it in batteries. Solar panels can also be named solar cell panels or solar electric panels.

Solar panels are often put together in groups called arrays or systems. A photovoltaic system has one or more solar panels. It also has an inverter that changes direct current to alternating current. Sometimes it includes other parts like charge controllers, meters, or solar trackers to catch the most sunlight. Most solar panels are found in big places called solar farms or on rooftop solar panels. They send power to the electricity grid.

Solar panels use sunlight, a clean and renewable energy source. They help reduce greenhouse gas emissions compared to using fuels like coal or oil. But they need sunlight to work best and must be cleaned often. They can be expensive at first. People use solar panels in homes, businesses, factories, and even in space with batteries.

History

See also: Solar cell § History, Timeline of solar cells, and Growth of photovoltaics

In 1839, a French scientist named Edmond Becquerel found that some materials make electricity when light shines on them. This was the first step to making solar panels. Later, in 1881, an American inventor named Charles Fritts built the first solar cell, but it did not work very well.

In 1954, scientists at Bell Labs made the first useful silicon solar cell. This is what many solar panels use today. Since then, solar energy has become cheaper and more common all over the world. Now, solar power helps provide electricity in many places, especially where other energy sources are expensive.

Theory and construction

Main article: Solar cell

Photovoltaic modules are made of many solar cells that change sunlight into electricity using the photovoltaic effect. Most modules use either wafer-based crystalline silicon cells or thin-film cells. The cells need to be protected from damage and moisture. Cells are linked together to make more electricity. Some solar panels are stiff, while others made from thin-film cells can bend.

Solar panels also have metal frames and parts that keep everything in place. The electricity made by solar panels depends on how much sunlight they get and what they are connected to. A special box on the back helps connect the panel to other parts. Many panels use special connectors to stay safe and work well in all kinds of weather.

Efficiency

See also: Solar-cell efficiency

Solar panels have different levels of efficiency. This means how well they change sunlight into electricity. Most panels can make between 100 to 365 Watts of power. This can change depending on where they are placed and the weather. A more efficient panel can do the same job in a smaller space. As of 2025, the best panels can turn about 24.5% of sunlight into electricity.

The amount of electricity a solar panel makes also depends on its location. Places closer to the equator, with more direct sunlight, will get more power than places farther away. Weather, like clouds or dust, can also affect how much power a panel makes.

Performance and degradation

Solar panels are tested to see how well they work. This testing looks at things like sunlight and temperature. The amount of power they make changes during the day and with the weather. To get the most power, solar panels should face the sun and have the right voltage.

Temperature matters for solar panels. Cooler temperatures can help them work better, but things like snow and less sunlight in winter can make them produce less power. Over time, solar panels may become a little less efficient because of sunlight and weather. Most panels are made to handle rain, hail, and snow.

Mounting and tracking

Main articles: Photovoltaic mounting system and Solar tracker

Large solar power plants often use systems where solar panels are held in place by racks or frames attached to the ground. These supports can be poles driven into the earth, concrete foundations, or weighted bases that don’t need to be dug into the ground.

Solar panels can also be placed on rooftops using special racks or weighted bases. Another option is a solar canopy, which is placed over areas like parking lots or carports. This provides shade and creates energy for things like electric vehicle charging. Portable solar panels are flexible and durable, perfect for charging devices while traveling or camping.

Solar trackers move panels to follow the sun, which can produce more energy but need more maintenance. Fixed panels can also be set at angles to catch the most sunlight depending on the time of year.

Maintenance

Solar panels can get less efficient when dust, pollen, and other particles cover them. This is called soiling. In very dusty areas, this can lower the power a panel makes. Cleaning the panels can help them work better again.

There are different ways to clean solar panels, like using hand tools or special machines. Scientists are also finding new ways to keep panels clean, such as using special coatings or electric charges to remove dust without water.

Waste and recycling

In 2021, there were 30 thousand tonnes of old solar panels that needed to be dealt with, and this number is expected to grow much larger in the future. Many parts of old solar panels, like glass and metals, can be reused. Some countries have rules to make sure solar panels are recycled properly.

Different types of solar panels need different ways of recycling. For silicon-based panels, the frames and boxes are taken apart, and the rest is crushed and sorted. For other types, special methods are used to separate materials. Many companies are working on better ways to recycle solar panels.

Production

See also: List of photovoltaics companies

The making of solar panels has grown very fast. Costs have gone down, and the panels work better than before. In 2019, many companies made and sent out lots of solar panels.

Most solar panels use silicon cells. These cells change sunlight into electricity. They are usually about 10–20% good at this, but new ones are even better. In 2018, some of the biggest companies making solar panels were Jinko Solar, JA Solar, Trina Solar, Longi solar, and Canadian Solar.

Price

The cost of solar power has dropped a lot over the years. In many places, it is now cheaper than electricity from fossil fuels. This change is called grid parity. Governments, like the IRS, help by giving tax credits to people who install solar panels.

Prices for solar panels depend on how much you buy. Small, medium, and large buyers all pay different amounts. Over time, solar panels have gotten much cheaper. For example, in 2012, solar panels cost about US$0.60 per watt, which is less than the US$150 they cost in 1970. The price keeps going down every year.

Standards

Solar panels follow rules to make sure they work safely. Important rules include IEC 61215 for crystalline silicon and IEC 61646 for thin film. There are also rules from Underwriters Laboratories, like UL 1703, and the CE mark to show they meet European standards. These rules help keep solar panels safe and reliable.

Applications

Main article: Applications of photovoltaics

See also: List of solar-powered products

Solar panels have many useful jobs. They can help farms by powering water pumps. In hospitals, they can keep medicines cool by running refrigerators. Solar panels also give power to many tools and machines we use each day. They are an important part of special power systems called photovoltaic systems.

Limitations

As more homes use solar panels, the way electricity works changes. Sometimes, homes make more electricity than they need and send extra power back to the grid. This can cause problems because the grid was not made to handle electricity flowing in two directions. For example, in Queensland, Australia, many homes used solar panels, which created challenges like too much voltage on the grid. There are ways to fix these issues, but they can be expensive.

To keep the power on during an outage, homes with solar panels often need a special battery. This battery stores extra electricity so homes can keep using power even when the grid is not working.

Quality assurance

Solar panels are tested to make sure they work well and last a long time. They usually last between 20 and 40 years. Tests include checking them, studying them in labs, and using computers to learn more. Companies like TÜV Rheinland and CSA Solar International help make sure solar panels are good quality.