Solar power, also called solar electricity, is the process of changing sunlight into electricity. This can happen directly through photovoltaics (PV), which are solar panels that use the photovoltaic effect to create an electric current. It can also happen indirectly through concentrated solar power systems, which use mirrors or lenses and tracking systems to focus sunlight into a hot spot, often to power a steam turbine.

Photovoltaics (PV) were first used for small and medium applications, such as powering calculators with one solar cell or providing electricity to homes not connected to the main power grid. Large solar power plants that use concentrated solar power were first built in the 1980s. Over time, as the cost of solar panels decreased, the amount of electricity produced by grid-connected solar PV systems has doubled every three years. Today, three-quarters of new electricity generation comes from solar power, with millions of rooftop solar systems and large-scale solar power plants being built worldwide.

In 2025, solar power provided 9% of the world’s electricity. In 2024, solar power produced over 1% of the world’s primary energy (2.7% by another method), adding more new electricity than coal did. Along with onshore wind power, large-scale solar power is the cheapest source of new electricity in most countries. China produces about half of the world’s solar power. Nearly half of all solar power installed in 2022 was placed on rooftops.

More low-carbon energy is needed to support electrification and reduce climate change. In 2022, the International Energy Agency said more work is needed to connect solar power to the electricity grid and address challenges related to policies, rules, and funding. Despite these challenges, solar power can help lower energy costs. Solar power is important for ensuring energy security.

Potential

Geography influences how much solar energy can be collected because some areas receive more sunlight than others. Places near the equator usually get more sunshine than areas farther away. Solar panels that move to follow the Sun's path can help collect more energy in regions farther from the equator. Clouds during the day can block sunlight, reducing the amount of light that reaches solar panels. The amount of available land also plays an important role in how much solar energy can be produced.

Technologies

Solar power plants use two main technologies:

• Photovoltaic (PV) systems use solar panels placed on rooftops or in large fields to turn sunlight directly into electricity.
• Concentrated solar power (CSP) systems use mirrors or lenses to focus sunlight into intense heat, which is used to make steam. The steam then turns a turbine to create electricity.

Solar cells use the photovoltaic effect to change light into electricity. The first solar cell was made by Charles Fritts in the 1880s. Ernst Werner von Siemens, a German industrialist, recognized the importance of this discovery. In 1931, Bruno Lange, a German engineer, created a solar cell using silver selenide instead of copper oxide. However, these early cells converted less than 1% of sunlight into electricity. In the 1940s, Russell Ohl's work led to the development of the silicon solar cell in 1954 by Gerald Pearson, Calvin Fuller, and Daryl Chapin. These early cells cost $286 per watt and had an efficiency of 4.5–6%. In 1957, Mohamed M. Atalla developed a process called silicon surface passivation at Bell Labs, which improved solar cell efficiency.

As of 2022, over 90% of solar power comes from crystalline silicon. A PV system produces direct current (DC), which changes with sunlight intensity. To use this electricity, it must be converted to alternating current (AC) using inverters. Solar cells are grouped into panels, and panels are connected to form arrays. These arrays are linked to an inverter, which adjusts the power to the correct voltage and frequency for AC use.

Many homes use grid-connected PV systems, especially in developed countries. These systems do not always need energy storage. However, in places like satellites, lighthouses, or developing countries, batteries or backup generators are often added to provide power during nighttime or low sunlight.

In a "vertical agrivoltaics" system, solar panels are placed upright on farmland to grow crops and generate energy at the same time. Other setups include floating solar farms, solar canopies over parking lots, and rooftop solar.

Thin-film solar cells are a newer type made by adding thin layers of materials like cadmium telluride (CdTe) or copper indium gallium diselenide (CIGS) onto surfaces such as glass or plastic.

Perovskite solar cells (PSCs) use materials like methylammonium lead halides or cesium lead halides. These materials are cheap to make and easy to produce. Laboratory tests show that PSCs have improved from 3.8% efficiency in 2009 to 27% in 2025 in single-junction designs, and 34.85% in silicon-based tandem cells. However, challenges remain, such as short lifespans, sensitivity to moisture, and toxicity from lead. Managing lead in PSCs is critical to avoid health risks like neurological disorders.

Concentrated solar power (CSP), also called "concentrated solar thermal", uses mirrors or lenses to focus sunlight into heat. This heat is used to generate electricity through steam-driven turbines.

As of 2021, the cost of electricity from CSP is more than twice that of PV. As of 2022, less than 1% of solar power comes from CSP.

Hybrid systems combine solar power with energy storage or other energy sources like hydroelectric power, wind, or batteries. This helps provide a steady power supply and reduce fluctuations in solar output. Hydroelectric power is widely available, and adding solar panels near existing hydro reservoirs is useful because hydro is flexible, cheaper at scale than batteries, and existing power lines can be used.

Development and deployment

Solar technology began to develop in the 1860s. People expected coal to run out, so experiments like those by Augustin Mouchot started. In 1884, Charles Fritts placed the first rooftop solar panels on a New York City building. These panels used selenium cells that were only 1% efficient. However, solar technology progress slowed in the early 1900s because coal and oil became cheaper and more useful. In the 1950s, Bell Telephone Laboratories tested silicon wafers coated with boron. Their "Bell Solar Battery" was 6% efficient, and one square yard of panels produced 50 watts of power. The first satellite with solar panels launched in 1957.

By the 1970s, solar panels were too expensive for most uses except satellites. In 1974, only six homes in North America used solar power for heating or cooling. The 1973 oil shortage and 1979 energy crisis made countries rethink energy policies and focus on solar technology again. Governments created programs like the U.S. Federal Photovoltaic Utilization Program and Japan’s Sunshine Program. Research centers were also formed in the U.S. (now NREL), Japan (NEDO), and Germany (Fraunhofer ISE). Between 1970 and 1983, solar installations grew quickly. President Jimmy Carter aimed for 20% of U.S. energy to come from solar by 2000, but his successor, Ronald Reagan, stopped funding for renewable research. Lower oil prices in the 1980s slowed solar growth until 1996.

Solar power grew steadily after 1996 because of better policies and lower costs. In 2023, China added 60% of the world’s new solar capacity. In the mid-1990s, solar panels for homes, businesses, and large power plants grew again because of oil supply problems, climate concerns, and better solar economics. In the early 2000s, European countries used feed-in tariffs, which guaranteed prices for solar electricity, leading to more solar projects.

Solar growth was first driven by Europe, but later shifted to Asia, especially China and Japan, and many other countries. Chinese companies became the largest solar equipment makers. Although concentrated solar power (CSP) grew more than ten times, it remained a small part of total solar use because solar panel costs dropped 85% from 2010 to 2020, while CSP costs only dropped 68%.

During the 2021–2022 energy crisis, solar remained the cheapest energy source in many countries because other energy costs, like natural gas, rose. In 2022, global solar power reached over 1 terawatt. However, fossil fuel subsidies slowed solar growth. Africa is now the fastest-growing solar market, helped by China. About half of all solar power is from large-scale projects.

Solar power is expected to become the largest renewable energy source by the end of the 2020s, surpassing hydropower. Large-scale solar is predicted to be the main electricity source in most regions by 2050, except sub-Saharan Africa. A photovoltaic power station, also called a solar farm, is a large system that supplies electricity to the grid, not just local users. It is different from concentrated solar power, which uses heat to generate electricity. As of 2019, 97% of large-scale solar power was from photovoltaic systems.

Some countries rate solar power in megawatt-peak (MWp), which is the maximum power a solar array can produce. Others use megawatt-ac (MWac), which is more comparable to other energy sources. Most solar farms are at least 1 MWp. By 2018, the largest solar farms exceeded 1 gigawatt. In 2019, about 9,000 solar farms were larger than 4 MWac, with a total capacity of over 220 gigawatts.

Most large solar farms are owned by independent companies, but community and utility-owned projects are growing. Earlier, government incentives like feed-in tariffs helped solar projects, but as costs dropped in the 2010s, these incentives became less needed.

Concentrated solar power plants, also called solar thermal plants, began in the 1980s. The Ivanpah Solar Power Facility in California is the largest, with 377 megawatts. Other large plants include Solnova, Andasol, and Extresol in Spain. CSP can store heat for up to 24 hours, which helps meet peak electricity demand. Many CSP plants use 3–5 hours of thermal storage to supply power during high-demand times, like 5 p.m.

Economics

In many countries, solar power is the least expensive way to produce electricity. The main costs for solar power include the price of solar panels, the frames that hold them, wiring, inverters, labor, land needed for installation, connecting to the power grid, maintenance, and the amount of sunlight the location receives.

Photovoltaic systems do not use fuel, and solar panels usually last between 25 and 40 years. Because of this, most of the cost of solar power comes from the initial investment and financing, which can be a problem in countries where contracts may not be honored, such as some in Africa. Some countries are considering setting maximum prices for solar energy, while others prefer agreements that guarantee a difference in price between solar energy and other energy sources.

The cost of high-power solar panels has decreased over time. In 1982, the cost per kilowatt was about $27,000. By 2006, this dropped to about $4,000 per kilowatt. In 1992, a photovoltaic system cost about $16,000 per kilowatt, and by 2008, the cost was about $6,000 per kilowatt. In 2025, residential solar power in the United States costs about $2.50 per watt (though solar shingles are much more expensive). Utility-scale solar power in 2025 costs about 25 cents per watt.

The amount of electricity solar power can produce in a region depends on sunlight levels, which change throughout the day and year. These levels are influenced by the region’s latitude and climate. The output of a photovoltaic system also depends on air temperature, wind speed, the type of sunlight, dirt or dust on the panels, and other factors.

Onshore wind power is often the cheapest electricity source in Northern Eurasia, Canada, parts of the United States, and Patagonia, Argentina. In other areas, solar power (or a mix of wind, solar, and other low-carbon energy sources) is considered the best option. Research from Exeter University suggests that by 2030, solar power will likely be the least expensive energy source everywhere except some Nordic countries.

Regions with the highest yearly sunlight levels are typically found in dry tropical and subtropical areas. Deserts near the equator often have few clouds and receive more than ten hours of sunlight daily. These hot deserts form the Global Sun Belt, which spans parts of Northern Africa, Southern Africa, Southwest Asia, the Middle East, Australia, and smaller deserts in North and South America.

Solar power is already (or is expected to become) the cheapest energy source in Central America, Africa, the Middle East, India, Southeast Asia, Australia, and several other regions.

Maps of solar irradiance measurements include the following areas:
• North America
• South America
• Europe
• Africa and the Middle East
• South and Southeast Asia
• Australia
• World

When solar energy is used directly by a household or business, the time it takes to recover the cost depends on how much electricity is not bought from the grid. However, electricity generation and use often do not match, so some or all of the energy may be sent back to the grid. In many places, the price paid for electricity sent to the grid is much lower than the price paid for electricity bought from the grid. This encourages users to use solar energy themselves. In some countries, such as Germany and Italy, special incentives for self-use have been introduced. In some areas of Germany, rules limit how much electricity can be sent to the grid to avoid overloading the system. Increasing self-use can reduce the need to send electricity to the grid without wasting it.

A good match between when solar energy is produced and when it is used is important for high self-use. This match can be improved with batteries or by adjusting electricity use. However, batteries are expensive, and their profitability often depends on providing other services, such as preventing power outages. Hot water storage tanks with electric heating can store solar energy at a lower cost. Appliances like dishwashers, dryers, and washing machines can be used at times that match solar production, though their impact on self-use may be limited.

The original goal of government incentives for solar power was to help the industry grow by starting with small projects, even when solar power was more expensive than other energy sources. This allowed the industry to reach a point where solar power costs are similar to other energy sources. After reaching this point, some policies now aim to support national energy independence, create high-tech jobs, and reduce carbon dioxide emissions.

Net metering is a method used for residential solar power. The price for the electricity produced by solar panels is the same as the price paid for electricity from the grid. Customers are billed based on the difference between the electricity they produce and the electricity they use.

A community solar project is a solar power installation that accepts money from and provides credit and tax benefits to multiple customers, such as individuals, businesses, and nonprofits. Participants usually invest in or subscribe to a specific amount of solar power capacity or electricity generation.

In some countries, import taxes are placed on solar panels brought from other countries.

Grid integration

Most electricity produced worldwide is used right away because traditional power generators can adjust to changes in demand, and storing electricity is usually more expensive. Solar power and wind power are types of renewable energy that produce power that varies based on weather and time of day. This means all the electricity they generate must be used immediately, sent through power lines to other places, or stored, such as in batteries. Since solar energy is not available at night, storing it to provide electricity continuously is important, especially in areas without a power grid and for future plans to use only renewable energy.

Solar power is not always available because it depends on the time of day and weather. However, solar energy can be predicted based on the time of day, location, and season. The difficulty of adding solar power to a power system varies depending on the location. In areas with hot summers and mild winters, solar energy often matches the need for electricity during the day when cooling is required.

Some solar power plants use thermal storage, such as high-temperature molten salts, to store energy. These salts are useful because they are inexpensive, can hold a lot of heat, and release it at temperatures that work with traditional power systems.

In solar power systems that operate independently, batteries are used to store extra electricity. In systems connected to the power grid, extra electricity can be sent to the grid. Programs like net metering and feed-in tariffs allow these systems to receive credit for the electricity they produce. This credit helps cover electricity used from the grid when the system cannot meet demand, effectively trading electricity with the grid instead of storing it. When solar and wind energy make up a small part of the grid’s power, other power sources can adjust their output. However, as these variable energy sources grow, the grid needs more balance. As battery prices drop, solar systems increasingly use rechargeable batteries to store extra electricity for later use, such as at night. These batteries help stabilize the grid by reducing large spikes in electricity demand.

Common battery types used in home solar systems include nickel-cadmium, lead-acid, nickel metal hydride, and lithium-ion. Lithium-ion batteries may replace lead-acid batteries soon because they are being developed rapidly and are expected to cost less due to large-scale production, such as at Tesla’s Gigafactory 1. Also, batteries from electric cars could be used in the future to store electricity in a vehicle-to-grid system. Since most cars are parked 95% of the time, their batteries could send electricity to the power grid and receive it again when needed.

Old electric car batteries can be reused. Other batteries used for solar systems include sodium-sulfur batteries (a type of molten salt battery) and vanadium redox batteries (a type of flow battery).

Solar power plants usually produce as much electricity as possible, even if it is not needed immediately. In systems without enough storage, other power sources like coal, biomass, natural gas, nuclear, or hydroelectricity adjust their output based on changes in solar power and electricity demand.

Hydroelectric dams work well with solar power because water can be stored in reservoirs and released as needed. In areas without suitable geography, pumped-storage hydroelectricity uses solar energy to pump water to a high reservoir during sunny days. At night or during bad weather, the stored water is released through a hydroelectric plant to a lower reservoir, restarting the process.

Hydroelectric and natural gas power plants can quickly adjust to changes in electricity demand. Coal, biomass, and nuclear plants take longer to adjust and can only follow predictable changes in demand. When solar and wind energy make up more than 20–40% of total electricity generation, the grid may need to invest in new connections, storage systems, or ways to manage electricity use. In countries with high solar energy production, like Australia, electricity prices may become negative during the day when solar energy is abundant, encouraging the use of battery storage.

Combining wind and solar power helps because they produce electricity at different times of the day and year. This makes their combined energy supply more stable and less variable than either alone. Solar energy is seasonal, especially in areas far from the equator, which suggests the need for long-term storage solutions like hydrogen or pumped hydroelectricity.

Environmental effects

Solar power is better for the environment than electricity made from fossil fuels like coal or gas. It does not release harmful gases when it is used, but making the solar panels does create some pollution. The amount of carbon dioxide made during production is less than 1 kilogram for each watt of power, and this number is expected to decrease as companies use more clean energy and recycled materials. Solar power has an initial environmental cost during production, which takes several years to balance out, but it provides clean energy for about 30 years after that.

Over its lifetime, solar farms produce less than 50 grams of greenhouse gases for every kilowatt-hour of electricity, but this can increase to 150 grams if batteries are used to store the energy. In comparison, a gas power plant without pollution controls releases about 500 grams per kilowatt-hour, and a coal power plant releases about 1,000 grams. Like other energy sources, most emissions from solar power come from building and transporting the equipment. Using cleaner energy in these processes can lower emissions even more.

Solar power uses about 7 watts of energy per square meter of land on average, which is much less than nuclear power (240 watts) or gas (480 watts). However, when the land needed for gas extraction and processing is included, gas power uses about the same amount of land as solar. A study from 2021 shows that to get 25% to 80% of electricity from solar farms by 2050, solar panels would need to cover 0.5% to 2.8% of the European Union, 0.3% to 1.4% of India, and 1.2% to 5.2% of Japan and South Korea. Using large areas for solar farms might cause problems like deforestation or loss of farmland. Some countries, like Japan and South Korea, use land for farming under solar panels or build floating solar farms to save space. Overall, solar power uses land in a way that has little effect on the environment. Using solar panels on buildings and other structures can reduce land use to levels similar to gas power.

Solar panels use some harmful materials, but only in small amounts. As of 2022, the environmental effects of a material called perovskite are not fully understood, but there are concerns about lead being used in some solar panels.

A 2021 study by the International Energy Agency predicts that the need for copper will double by 2040. The study warns that the supply of copper must grow quickly to meet the needs of solar power and upgrades to the electrical grid. More of other materials, like tellurium and indium, might also be needed.

Recycling solar panels can help. Sometimes, older panels are reused in other countries, such as in Africa. Some countries have rules for recycling solar panels. Although solar power is already cheaper to maintain than other energy sources, some experts suggest that solar systems should be designed to be easier to repair.

Solar panels can raise the temperature in the areas where they are placed. In large solar farms in deserts, this effect can be stronger than the heat from cities.

A very small part of solar power is concentrated solar power, which uses more water than gas power plants. This can be a problem because concentrated solar power is often built in deserts where water is already scarce.

Politics

Some people say that the economic benefits of switching to solar energy and other clean energy sources are so large that the change cannot be stopped. However, slowing this change could cause more harm to the environment. Groups that support fossil fuels, like oil and gas, have been criticized for trying to slow the move to clean energy. Money given to fossil fuel companies by governments can make the transition to clean energy harder. Once solar power systems are built, they are not affected by international conflicts, unlike oil and gas, which helps make energy supplies more secure. Some people who believe in limited government support solar energy because it reduces reliance on government and weakens dependence on old electricity systems. However, some right-wing political groups are against or unsure about using solar energy. Far-right political groups have different views depending on the country, with some opposing solar energy as part of their rejection of climate change science. While some environmental groups support solar energy to help reduce climate change, others are against building new power lines.

As of 2022, more than 40% of the world’s polysilicon manufacturing is done in Xinjiang, China. This has raised concerns about human rights issues in the region. The International Solar Energy Society says that China’s control over solar manufacturing is not a major problem. They believe solar manufacturing is unlikely to grow beyond $400 billion per year and that other countries would have time to build their own industries if China stopped supplying solar panels. Companies may try to influence governments to support or oppose taxes on imported solar panels.