Solar panel

A solar panel is a device that converts sunlight into electricity by using multiple solar modules that consist of photovoltaic (PV) cells. PV cells are made of materials that produce excited electrons when exposed to light. These electrons flow through a circuit and produce direct current electricity, which can be used to power various devices or be stored in batteries. Solar panels can also be called solar cell panels, or solar electric panels.

Solar panels are usually arranged in groups called arrays or systems. A photovoltaic system includes one or more solar panels, an inverter that changes direct current electricity to alternating current, and sometimes other parts such as charge controllers, meters, or solar trackers to get the most sunlight. Most panels are found in solar farms or on rooftop solar panels, which send power to the electricity grid.

Solar panels use a renewable and clean energy source, and they help lower greenhouse gas emissions compared to energy from fuels like coal or oil. However, they need sunlight to work well, must be cleaned regularly, and can cost a lot at first. People use solar panels in homes, businesses, factories, and even in space together with batteries.

History

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

In 1839, a French scientist named Edmond Becquerel discovered that certain materials could create an electric charge when exposed to light. This was the first step toward creating solar panels. Later, in 1881, an American inventor named Charles Fritts made the first solar cell, though it was not very efficient.

In 1954, scientists at Bell Labs created the first practical silicon solar cell, which is the basis for many modern solar panels. Since then, the cost of solar energy has dropped dramatically, making it more accessible around the world. Today, solar power is a major source of electricity in many places, especially in areas that rely on expensive fuel imports.

Theory and construction

Main article: Solar cell

Photovoltaic modules are made up of many solar cells that work together to turn sunlight into electricity using the photovoltaic effect. Most modules use either wafer-based crystalline silicon cells or thin-film cells. The cells inside the module need to be protected from damage and moisture. Cells are connected together to increase the amount of electricity they can produce. Some solar panels are rigid, while others made from thin-film cells can bend.

Solar panels also have metal frames and parts that help hold everything together. The electricity made by solar panels depends on how much sunlight hits them and what the panel is connected to. A special box on the back of the panel helps connect it to other parts of the system. Many panels use special connectors to make sure they stay safe and work well in weather.

Efficiency

See also: Solar-cell efficiency

Solar panels have different levels of efficiency, which means how well they turn sunlight into electricity. Most panels can make between 100 to 365 Watts of power, but 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 under specific conditions to measure their performance, such as how much sunlight they receive and their temperature. Their output changes throughout the day and with different weather. To work best, solar panels should face the sun directly and be similar in voltage.

Temperature affects how well solar panels work. Cooler temperatures can make them more efficient, but winter conditions like snow and less sunlight can reduce overall power generation. Over time, solar panels may lose a small amount of efficiency each year due to exposure to sunlight and weather conditions. Most panels are built to withstand rain, hail, and snow.

Mounting and tracking

Main articles: Photovoltaic mounting system and Solar tracker

Large solar power plants often use ground-mounted systems, where solar panels are held in place by racks or frames attached to supports in 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, providing shade and creating 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 lose some of their efficiency when dust, pollen, and other particles get on them. This is called soiling. In very dusty places, this can reduce the power a panel makes by up to 30%. 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 working on new ways to keep panels clean, such as using special coatings or electric charges to remove dust without water.

Waste and recycling

There were 30 thousand tonnes of solar panel waste in 2021, and this amount is expected to grow a lot in the future. Many parts of old solar panels can be reused, including glass and metals. 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 production of solar panels has grown very quickly, with costs going down while efficiency and output have gone up. In 2019, many solar panel makers increased their shipments greatly and became big players in the industry.

Most solar panels are made using silicon cells, which can turn sunlight into electricity. These cells are usually about 10–20% efficient, but newer models 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 has happened since 2012 and 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 buyers, medium buyers, 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 much less than the US$150 they cost in 1970. The price keeps going down every year.

Standards

Solar panels follow specific rules to make sure they work safely and well. Important standards include IEC 61215 for crystalline silicon performance, IEC 61646 for thin film performance, and others like IEC 61730 for safety. There are also rules from organizations like Underwriters Laboratories, such as UL 1703, and the CE mark to show that a product meets European standards. These standards help ensure solar panels are reliable and safe to use.

Applications

Main article: Applications of photovoltaics

See also: List of solar-powered products

Solar panels have many useful applications. They can provide power for farming, like helping water pumps for irrigation. In hospitals, solar panels can help keep medicines cool by providing electricity for refrigeration. Solar panels are also used to power many different machines and tools we use every day, making them a key part of special systems called photovoltaic systems.

Limitations

As more homes use solar panels, the way electricity flows changes. Sometimes, homes make more electricity than they need, sending extra power back to the grid. This can cause problems because the grid was not built 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 as well. This battery stores extra electricity so homes can keep using power even when the grid is not working.

Quality assurance

Solar modules, or panels, are tested to make sure they work well and last a long time—usually between 20 and 40 years. These tests include physical checks, lab studies, and computer analyses at different points in their life cycle. Companies like TÜV Rheinland and CSA Solar International help make sure solar panels meet quality standards.