Solar power, also called solar electricity, is the process of changing sunlight into electricity. This can happen directly through photovoltaics (PV), which use solar panels, or indirectly through concentrated solar power (CSP), which uses mirrors or lenses to focus sunlight. Solar panels use the photovoltaic effect to turn light into an electric current. Concentrated solar power systems use mirrors or lenses and tracking devices to gather sunlight into a single hot spot, which is often used to power a steam turbine.

Photovoltaics (PV) were first used for small and medium-sized purposes, such as powering calculators with one solar cell or providing electricity to remote homes with off-grid solar systems. Commercial concentrated solar power plants were developed in the 1980s. Since then, as the cost of solar panels has decreased, the amount of electricity produced by grid-connected solar PV systems has doubled roughly every three years. Three-quarters of new electricity generation capacity added globally is from solar power, with millions of rooftop solar systems and large-scale photovoltaic power plants being built.

In 2024, solar power provided 7% of the world’s electricity and over 1% of primary energy (2.7% using a substitution method). It added twice as much new electricity as coal did. Along with onshore wind power, large-scale solar energy is the cheapest source of new electricity in most countries. China produces about half of the world’s solar power. Nearly half of the solar power installed in 2022 was placed on rooftops.

More low-carbon electricity is needed to reduce climate change and support electrification. In 2022, the International Energy Agency stated that more work is needed to improve how electricity grids integrate solar power and to address challenges related to policies, regulations, and funding. Despite these challenges, solar power can significantly lower energy costs. Solar energy is important for ensuring energy security.

Potential

Geography influences how much solar energy a place can produce because some areas get more sunlight than others. Areas near the equator usually receive more sunlight than areas farther away. However, solar panels that move to follow the Sun's path can help increase solar energy production in places that are not near the equator. Clouds during the day can block sunlight, which reduces 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 collected.

Technologies

Solar power plants use two main technologies:

• Photovoltaic (PV) systems use solar panels, either on rooftops or in large solar farms on the ground, to change sunlight directly into electricity.
• Concentrated solar power (CSP) systems use mirrors or lenses to focus sunlight into intense heat, which creates steam to power turbines and generate electricity.

The photovoltaic effect in solar cells is the process that turns light into electric current. 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, German engineer Bruno Lange created a photo cell using silver selenide instead of copper oxide. Early selenium cells converted less than 1% of sunlight into electricity. In the 1940s, Russell Ohl’s research led to Gerald Pearson, Calvin Fuller, and Daryl Chapin developing the silicon solar cell in 1954. These early cells cost $286 per watt and had efficiencies of 4.5–6%. In 1957, Mohamed M. Atalla developed a process called silicon surface passivation at Bell Labs. This process has been essential for improving solar cell efficiency.

As of 2022, over 90% of the solar market uses crystalline silicon. A photovoltaic system produces direct current (DC) electricity, which changes based on sunlight intensity. For practical use, DC is usually converted to alternating current (AC) using inverters. Solar cells are connected in panels, and panels are linked together to form arrays. These arrays are connected to inverters, which adjust the electricity to the right voltage and frequency for AC power.

Many residential solar systems are connected to the electrical grid, especially in developed countries. These grid-connected systems do not always need energy storage. In some cases, like satellites, lighthouses, or in developing countries, batteries or other power sources are added as backup. These stand-alone systems allow energy use at night or during low sunlight.

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

A thin-film solar cell is a second-generation solar cell made by applying thin layers of photovoltaic material, such as glass, plastic, or metal. These cells are used in technologies like cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous thin-film silicon (a-Si, TF-Si).

A perovskite solar cell (PSC) uses a material with a specific structure, often a mix of organic and inorganic compounds, to capture light. These cells are cheap to make and easy to produce. Laboratory tests show their efficiency increased from 3.8% in 2009 to 27% in 2025 for single-junction cells, and up to 34.85% in silicon-based tandem cells. However, challenges remain, such as their sensitivity to moisture, short lifespan, and potential toxicity from lead. Managing lead in PSCs is important to avoid health risks like neurological problems.

Concentrated solar power (CSP), also called "concentrated solar thermal," uses mirrors and tracking systems to focus sunlight into heat, which generates electricity through steam turbines.

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

A hybrid system combines solar power with energy storage or other energy sources, such as hydroelectric, wind, or batteries. Combining these can help adjust power output to match demand or reduce solar power fluctuations. 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 often be used.

Development and deployment

The early development of solar technology began in the 1860s because people thought coal would soon run out. Experiments by Augustin Mouchot helped start this progress. In 1884, Charles Fritts placed the first rooftop solar panel system in New York City. This system used selenium cells that were only 1% efficient. However, solar technology development slowed in the early 1900s because coal and petroleum became more available, cheaper, and more useful. In the 1950s, Bell Telephone Laboratories studied silicon wafers covered with boron. Their "Bell Solar Battery" was 6% efficient, producing 50 watts of power per square yard. The first satellite with solar panels was launched in 1957.

By the 1970s, solar panels were still too expensive for most uses other than satellites. In 1974, only six homes in North America used solar power for heating or cooling. The 1973 oil shortage and the 1979 energy crisis caused countries to change their energy policies and focus more on solar technology.

Programs like the Federal Photovoltaic Utilization Program in the United States and the Sunshine Program in Japan helped support solar development. Research centers were created in the U.S. (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer ISE). Between 1970 and 1983, solar installations grew quickly. President Jimmy Carter aimed to produce 20% of U.S. energy from solar by 2000, but his successor, Ronald Reagan, cut funding for renewable energy research. Falling oil prices in the 1980s slowed solar growth from 1984 to 1996.

• Yearly solar generation by continent
• Solar power grew steadily because of better policies and lower costs. In 2023, China added 60% of the world’s new solar capacity.
• Growth of solar power since 1996 on a semi-log scale
• Electricity production by source

In the mid-1990s, solar power for homes, businesses, and large power plants grew again because of problems with oil and gas supplies, concerns about global warming, and better economics of solar compared to other energy sources. In the early 2000s, feed-in tariffs—policies that guarantee a fixed price for solar electricity—helped increase solar use in Europe.

For many years, Europe led global solar growth, but this shifted to Asia, especially China and Japan, and to other countries worldwide. Chinese companies became the largest producers of solar equipment. While concentrated solar power (CSP) grew more than ten times, it remained a small part of total solar energy because the cost of utility-scale solar dropped 85% between 2010 and 2020, while CSP costs only dropped 68% in the same time.

During the 2021–2022 energy crisis, even though material costs like polysilicon rose, solar power remained the cheapest energy source in many countries because other energy costs, like natural gas, increased. In 2022, global solar generation reached over 1 terawatt for the first time. However, fossil fuel subsidies slowed solar growth. Africa is now the fastest-growing solar market, largely supported by China.

About half of all solar power is from large-scale utility projects.

Solar power is expected to become the largest renewable energy source by the end of the 2020s, surpassing hydropower. Utility-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 park or solar farm, is a large solar system connected to the power grid that supplies electricity to the public. Unlike smaller solar systems, these projects provide power at the utility level, not just to local users. Utility-scale solar is often used to describe this type of project.

This is different from concentrated solar power (CSP), another large-scale solar technology that uses heat to generate electricity. Both methods have advantages and disadvantages, but photovoltaic technology has been used more widely. As of 2019, about 97% of utility-scale solar power was from photovoltaic systems.

In some countries, the power of photovoltaic stations is measured in megawatt-peak (MWp), which is the maximum power output under ideal conditions. In other countries, the size and efficiency of the solar panels are stated. Canada, Japan, Spain, and the United States often use megawatt AC (MW AC), a measure that compares directly to other power sources. Most solar farms are at least 1 MWp. By 2018, the largest solar farms exceeded 1 gigawatt. By the end of 2019, about 9,000 solar farms were larger than 4 MW AC, with a combined capacity of over 220 gigawatts AC.

Most large solar farms are owned by independent companies, but community and utility-owned projects are increasing. In the past, many projects relied on government incentives like feed-in tariffs or tax credits. However, as solar costs dropped in the 2010s and solar became as cheap as other energy sources in most markets, these incentives are no longer needed.

Commercial concentrated solar power (CSP) plants, also called solar thermal power stations, were first developed in the 1980s. The Ivanpah Solar Power Facility in California’s Mojave Desert is the largest CSP plant, with a capacity of 377 megawatts. Other large CSP plants include Solnova, Andasol, and Extresol in Spain. The main advantage of CSP is its ability to store heat, allowing electricity to be generated for up to 24 hours. Many CSP plants use 3 to 5 hours of thermal storage to meet peak electricity demand, which usually happens around 5 p.m.

Economics

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

Photovoltaic systems do not use fuel, and solar panels usually last 25 to 40 years. Because of this, the initial cost of buying and financing the system makes up 80% to 90% of the total cost. This can be a challenge in some countries where agreements might not be honored, such as parts of Africa. Some countries are thinking about setting maximum prices for solar energy, while others prefer agreements that guarantee a certain price difference.

The cost of high-power solar panels has decreased over time. In 1982, the cost was about $27,000 per kilowatt. 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 a solar system can produce depends on the amount of sunlight it receives, which changes throughout the day and year. Sunlight levels are influenced by a region’s latitude and climate. The power output of a photovoltaic system also depends on temperature, wind speed, the type of sunlight, and how much dust or dirt is on the panels.

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

Areas with the highest yearly sunlight are typically in dry tropical and subtropical regions. 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 stretches across parts of Northern Africa, Southern Africa, Southwest Asia, the Middle East, and Australia, as well as smaller deserts in North and South America.

Solar power is (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 show measurements of sunlight (direct normal irradiance and global horizontal irradiance) for the following areas:
– North America
– South America
– Europe
– Africa and the Middle East
– South and Southeast Asia
– Australia
– The world

When people use solar energy for their own needs, the time it takes to recover the investment depends on how much electricity they avoid buying from the grid. However, solar energy is often produced at times when it is not needed, and some or all of the energy is sent back to the grid. Electricity is sold when there is extra, and bought when needed. The prices for selling and buying electricity affect the overall cost. In many places, the price paid for solar electricity sold to the grid is much lower than the price for buying electricity, which encourages people to use solar energy themselves. Some countries, like Germany and Italy, have special programs to support self-use of solar energy. In some areas of Germany with many solar panels, rules have limited how much electricity can be sent back to the grid. Increasing self-use can help reduce the amount of electricity sent to the grid without wasting any.

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 when electricity is used. 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 energy production, but their impact on self-use may be limited.

The original goal of government programs to support solar power was to help the industry grow, even when solar power was more expensive than other energy sources. These programs allowed the industry to reach a point where solar power costs are equal to or less than other energy sources. After reaching this point, some policies now focus on helping countries become more energy independent, creating high-tech jobs, and reducing 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 the customer pays for electricity from the grid. The customer is charged based on the difference between the electricity they produce and the electricity they use.

A community solar project is a solar power system that allows multiple people, including individuals, businesses, and organizations, to invest in solar energy. Participants usually support a certain amount of power generation or capacity from a remote solar installation and receive credit or tax benefits.

In some countries, taxes are added to solar panels imported from other countries.

Grid integration

Most electricity made around the world 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 unevenly, meaning all the electricity they generate must be used locally, sent through power lines to other places, or stored (for example, in batteries). Since solar energy is not available at night, storing it to provide continuous electricity is an important challenge, especially in areas without a power grid and for future plans to use only renewable energy.

Solar power is not always available because of day and night cycles and changing weather. However, the amount of solar power produced 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 power often matches the need for cooling during the day.

Concentrated solar power plants can store energy using thermal storage, such as high-temperature molten salts. These salts are good for storage because they are low-cost, can hold a lot of heat, and can provide heat at temperatures that work with traditional power systems.

In solar power systems that operate alone, batteries are often 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 give credit to these systems for the electricity they produce. This credit can be used to pay for electricity taken from the grid when the system cannot meet demand, effectively trading electricity with the grid instead of storing it. When wind and solar power make up a small part of the grid, other power sources can adjust their output. However, as these variable energy sources grow, the grid needs more balance. As prices drop, solar systems increasingly use rechargeable batteries to store extra electricity for later use, such as at night. Grid-storage batteries help stabilize power systems by reducing large spikes in electricity demand over several hours.

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 more and are expected to cost less due to large production facilities like Tesla Gigafactory 1. Also, the lithium-ion batteries in electric cars could be used in the future to store energy in a vehicle-to-grid system. Since most cars are parked about 95% of the time, their batteries could send electricity to the power grid and receive it again.

Old electric vehicle batteries can be reused. Other batteries used for solar systems include sodium-sulfur and vanadium redox batteries, which are types of molten salt and flow batteries, respectively.

Solar power plants usually produce as much electricity as possible, even if it is not always used. In systems without enough grid storage, other power sources like coal, biomass, natural gas, nuclear, or hydroelectricity must increase or decrease their output to match changes in solar electricity and demand.

Traditional hydroelectric dams work well with solar power because water can be stored or released from a reservoir as needed. In places without suitable geography, pumped-storage hydroelectricity can use solar power 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 cycle.

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

Combining wind and solar power helps because they produce electricity at different times of the day and year. This makes the total power supply more steady and less likely to change suddenly. Solar power changes with the seasons, especially in areas far from the equator, which suggests a need for long-term storage solutions like hydrogen or pumped hydroelectricity.

Environmental effects

Solar power is cleaner than electricity made from fossil fuels and is better for the environment than burning fuels. Solar power does not create harmful emissions during its use, but making the panels causes some pollution. The pollution from making solar panels is less than 1 kilogram of carbon dioxide per watt of power, and this amount is expected to decrease as manufacturers use more clean energy and recycled materials. Solar power has an initial environmental cost from production, with a carbon payback time of several years as of 2022, but it provides clean energy for the rest of its 30-year lifespan.

The total greenhouse gas emissions from solar farms during their entire life cycle are less than 50 grams per kilowatt-hour (kWh), but with battery storage, this could increase to 150 grams per kWh. In comparison, a gas power plant without carbon capture emits about 500 grams per kWh, and a coal power plant emits about 1,000 grams per kWh. Like all energy sources, most emissions from solar power come from construction. Using low-carbon energy in manufacturing and transporting solar devices can further reduce emissions.

The average power density of solar power is about 7 watts per square meter, compared to 240 watts per square meter for nuclear power and 480 watts per square meter for gas. However, when considering the land needed for gas extraction and processing, gas power may not use much more land than solar. A 2021 study suggests that to get 25% to 80% of electricity from solar farms by 2050, 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 opposition from residents, deforestation, and loss of farmland. However, some countries, like South Korea and Japan, use land for agriculture under solar panels or use floating solar farms alongside other clean energy sources. Worldwide, solar power uses land with minimal ecological impact. Land use can be reduced to match gas power by installing solar panels on buildings and other developed areas.

Some harmful materials are used in making solar panels, but they are usually in small amounts. As of 2022, the environmental impact of perovskite is hard to estimate, but there are concerns about lead being a problem.

A 2021 study by the International Energy Agency predicts that the demand for copper will double by 2040. The study warns that supply must increase quickly to meet the needs of large solar projects and grid improvements. More tellurium and indium may also be required.

Recycling may help. When solar panels are replaced with more efficient ones, older panels are sometimes reused in developing countries, such as in Africa. Some countries have rules for recycling solar panels. Although maintenance costs are already low compared to other energy sources, some experts suggest solar systems should be designed to be easier to repair.

Solar panels can raise local temperatures. In large solar installations in deserts, this effect can be stronger than the urban heat island effect.

A very small part of solar power is concentrated solar power. This type of solar power may use more water than gas power plants. This can be a problem because concentrated solar power needs strong sunlight and is often built in deserts.

Politics

Some people say that even though the economic benefits of switching to solar energy are very large, slowing this change could cause more harm to the environment. The group that supports using fossil fuels, like oil and coal, has been criticized for trying to slow the move to clean energy. Money given to fossil fuel companies by governments makes it harder to switch to solar. Once solar energy systems are built, they can keep producing electricity without being affected by political 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 the need for government control and dependence on old electricity systems. However, some right-wing political groups disagree with or are divided about using solar energy. Far-right political parties have different views in different countries, with some opposing solar energy as part of their belief that climate change is not real. While groups that focus on protecting the environment often support solar energy to reduce climate change, some environmentalists are against building new power lines.

In 2022, more than 40% of the world’s ability to make a key material for solar panels, called polysilicon, was in Xinjiang, China. This has raised concerns about human rights issues, including reports of detention camps in Xinjiang. The International Solar Energy Society says that China’s control over solar manufacturing is not a problem because they believe solar production will not grow beyond 400 billion USD each year, and other countries would have time to develop their own industries if China stopped supplying materials. Companies may try to influence governments to support or oppose taxes on solar panels imported from other countries.