Solar power is a form of renewable energy derived from sunlight or artificial light, converted into electricity. Solar power is virtually nonpolluting and abundantly available, and its use has become more attractive to those seeking sustainability as a strategy to counter the climate crisis. Solar cells (photovoltaic cells) directly convert solar radiation into electricity. These cells generate a small electric voltage when light strikes the junction between a metal and a semiconductor. Connecting large numbers of cells, as in solar panel arrays, can generate significant electric power. Concentrated solar power plants use mirrors or lenses to focus sunlight onto a receiver, increasing the light's intensity to produce high temperatures. The heat then operates a boiler, which creates steam for a steam turbine electric generator power plant.

How do solar panels turn sunlight into electricity?

Solar panels convert sunlight into electricity using solar cells, commonly made of crystalline silicon. These cells feature two layers of silicon, one with excess electrons (n-type) and another with a deficit (p-type), forming a p-n junction. When light strikes the solar cell, photons excite electrons, allowing them to move through the material. The p-n junction's electric field then directs these electrons into an external circuit, generating a direct current that can perform work. Multiple solar cells are combined to form modules and panels. This electricity can be used directly or stored in batteries. Photovoltaic systems offer a non-polluting alternative to fossil fuels.

What materials are used to make solar panels?

Solar panels mainly use crystalline silicon-type solar cells, which convert the Sun's energy into usable electrical energy. These cells consist of layers of elemental silicon and elements like phosphorus and boron. The added elements create an n-type layer with excess electrons and a p-type layer with a deficit of electrons, forming a p-n junction. Other materials used in thin-film solar cells include cadmium telluride, copper indium gallium selenide (CIGS), and gallium arsenide (GaAs). Cadmium telluride is a common, cost-effective option, while CIGS shows promise but is traditionally more costly. GaAs achieves high efficiency but is expensive, limiting its use to spacecraft and satellites. Amorphous silicon is another option, as it is cheaper to manufacture but has lower efficiency.

What are the two main types of solar power technology?

The two main types of solar power technology are: Solar Photovoltaics: Solar radiation is converted directly into electricity using solar cells. When light strikes the junction between a metal and a semiconductor, a small electric voltage is generated. Connecting many cells together in solar panel arrays can generate significant power. Concentrated Solar Power: This technology employs lenses or mirrors to concentrate sunlight onto a small receiver, increasing the light's intensity to produce high temperatures. The heat is then used to operate a boiler, which generates steam for a steam turbine electric generator power plant.

How is solar power stored for use when it's cloudy or at night?

Solar power can be stored using batteries, which are essential for compensating for the absence of electrical output from the cells at night or in overcast conditions. These batteries store direct current (DC) electricity at a fixed voltage determined by the panel specifications. Another method involves storing the radiant heat of the sun in water coils placed beneath heat-absorbing panels. The water is then stored in a tank for later use in heating lines or to provide hot water. Concentrated solar power plants can also store energy by focusing sunlight onto a receiver to produce high temperatures, which can then operate a boiler and generate steam for a steam turbine electric generator power plant.

What are some benefits and challenges of using solar power on a large scale?

Large-scale solar power offers numerous benefits, including reducing carbon emissions and electricity costs. Community solar programs provide access to clean energy without the high installation costs, offering monthly discounts on energy bills. Grid-connected systems can supplement power grids and allow individuals to supply their own power, feeding excess energy back into the grid. Challenges include the high initial cost of solar panel systems and the space needed for less-efficient panels. Solar power generation is intermittent, depending on sunlight availability, necessitating battery systems that add to the overall cost. Additionally, integrating solar arrays with power grids requires complex inverters and protective gear.

solar power

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Rows of solar panels angled toward the sun, with bright sunlight reflecting off the panels and grassy ground beneath.

World map color-coded to show photovoltaic solar power potential, with higher potential indicated by warmer colors such as orange and red, and lower potential by cooler colors such as green and blue. Regions with the highest solar energy potential include parts of western North America, northern and southern Africa, the Middle East, Australia, and parts of South America, while areas with lower potential are found in northern Europe, Russia, and parts of Canada. The map includes a scale for daily

A metal tea kettle sits on a large reflective solar cooker outdoors in a Himalayan village in Nepal, with stone walls and a building visible in the background.

Detailed labeled diagram of the completed Mir space station as of 1996, showing its modular structure with labeled components including Kvant 1, Kvant 2, Kristall, Spektr, Priroda, the Mir base block, shuttle docking module, and multiple solar panels. A Soyuz TM crew spacecraft and an unmanned Progress cargo ferry are shown docked to the station. Key features such as attitude-control thrusters, airlock hatch, communication antennas, and docking ports are also identified.

The future of solar power: Multi-junction solar cells

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Related Topics:: solar cell; smart grid; solar energy; space-based solar power; solar tracker

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Solar panels An array of solar panels convert sunlight to electricity.

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Top Questions

What is solar power?
Solar power is a form of renewable energy derived from sunlight or artificial light, converted into electricity. Solar power is virtually nonpolluting and abundantly available, and its use has become more attractive to those seeking sustainability as a strategy to counter the climate crisis.

Solar cells (photovoltaic cells) directly convert solar radiation into electricity. These cells generate a small electric voltage when light strikes the junction between a metal and a semiconductor. Connecting large numbers of cells, as in solar panel arrays, can generate significant electric power.

Concentrated solar power plants use mirrors or lenses to focus sunlight onto a receiver, increasing the light's intensity to produce high temperatures. The heat then operates a boiler, which creates steam for a steam turbine electric generator power plant.
6 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do solar panels turn sunlight into electricity?
Solar panels convert sunlight into electricity using solar cells, commonly made of crystalline silicon. These cells feature two layers of silicon, one with excess electrons (n-type) and another with a deficit (p-type), forming a p-n junction.

When light strikes the solar cell, photons excite electrons, allowing them to move through the material. The p-n junction's electric field then directs these electrons into an external circuit, generating a direct current that can perform work. Multiple solar cells are combined to form modules and panels. This electricity can be used directly or stored in batteries. Photovoltaic systems offer a non-polluting alternative to fossil fuels.
2 Britannica Sources
1. solar panel: Solar cells
2. materials science: Photovoltaics
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What materials are used to make solar panels?
Solar panels mainly use crystalline silicon-type solar cells, which convert the Sun's energy into usable electrical energy. These cells consist of layers of elemental silicon and elements like phosphorus and boron. The added elements create an n-type layer with excess electrons and a p-type layer with a deficit of electrons, forming a p-n junction.

Other materials used in thin-film solar cells include cadmium telluride, copper indium gallium selenide (CIGS), and gallium arsenide (GaAs). Cadmium telluride is a common, cost-effective option, while CIGS shows promise but is traditionally more costly. GaAs achieves high efficiency but is expensive, limiting its use to spacecraft and satellites. Amorphous silicon is another option, as it is cheaper to manufacture but has lower efficiency.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What are the two main types of solar power technology?
The two main types of solar power technology are:
- Solar Photovoltaics: Solar radiation is converted directly into electricity using solar cells. When light strikes the junction between a metal and a semiconductor, a small electric voltage is generated. Connecting many cells together in solar panel arrays can generate significant power.
- Concentrated Solar Power: This technology employs lenses or mirrors to concentrate sunlight onto a small receiver, increasing the light's intensity to produce high temperatures. The heat is then used to operate a boiler, which generates steam for a steam turbine electric generator power plant.
2 Britannica Sources
1. solar energy: Electricity generation
2. solar power: Concentrated solar power
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How is solar power stored for use when it's cloudy or at night?
Solar power can be stored using batteries, which are essential for compensating for the absence of electrical output from the cells at night or in overcast conditions. These batteries store direct current (DC) electricity at a fixed voltage determined by the panel specifications. Another method involves storing the radiant heat of the sun in water coils placed beneath heat-absorbing panels. The water is then stored in a tank for later use in heating lines or to provide hot water.

Concentrated solar power plants can also store energy by focusing sunlight onto a receiver to produce high temperatures, which can then operate a boiler and generate steam for a steam turbine electric generator power plant.
6 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What are some benefits and challenges of using solar power on a large scale?
Large-scale solar power offers numerous benefits, including reducing carbon emissions and electricity costs. Community solar programs provide access to clean energy without the high installation costs, offering monthly discounts on energy bills. Grid-connected systems can supplement power grids and allow individuals to supply their own power, feeding excess energy back into the grid.

Challenges include the high initial cost of solar panel systems and the space needed for less-efficient panels. Solar power generation is intermittent, depending on sunlight availability, necessitating battery systems that add to the overall cost. Additionally, integrating solar arrays with power grids requires complex inverters and protective gear.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

solar power, form of renewable energy generated by the conversion of solar energy (namely sunlight) and artificial light into electricity. In the 21st century, as countries race to cut greenhouse gas emissions to curb the unfolding climate crisis, the transition to renewable energies has become a critical strategy. Virtually nonpolluting and abundantly available, solar power stands in stark contrast to the combustion of fossil fuels (namely coal, petroleum, and natural gas) that are driving global warming and has become increasingly attractive to individuals, businesses, and governments on the path to sustainability.

Solar Power Timeline

1839: Edmond Becquerel discovers the photovoltaic effect
1860: Augustin Mouchot develops one of the first practical solar-powered systems
1876: Demonstration of first selenium solar cell
1913: Frank Shuman builds one of the first large solar-thermal power plants in Egypt
1954: Bell Labs develops the first practical silicon solar cell
1958: Solar cells power the Vanguard 1 satellite
1973–74: Oil crisis spurs modern investment in solar power research and development
1981: Solar One, one of the first utility-scale solar thermal power plants, begins operation
2000s: Rapid decline in costs drives global adoption of solar photovoltaics
2014: Ivanpah Solar Electric Generating System, a concentrated solar thermal plant, opens
2020s: Solar becomes the cheapest source of new electricity in many regions of the world
2025: Global solar capacity growth sets a new record

The potential for solar energy conversion is enormous, since about 200,000 times the world’s total daily electricity demand is received by Earth in the form of solar energy. In fact, calculations based on the world’s projected energy consumption by 2030 suggest that global energy demands could be fulfilled by solar panels operating at 20 percent efficiency and covering about 496,805 square km (191,817 square miles) of Earth’s surface—an area close to the size of Turkmenistan or Spain. The material requirements would be enormous but feasible, as silicon is the second most abundant element in Earth’s crust. These factors have led solar proponents to envision a future “solar economy” in which practically all of humanity’s energy requirements are satisfied by cheap, clean, renewable sunlight. Unfortunately, though solar energy itself is free, the high cost of its collection, conversion, and storage still limits its exploitation in many places. For an overview of solar energy and its applications, see solar energy. For a discussion of the design, structure, and operation of photovoltaic cells, see solar cell.

In the first quarter of 21st century, solar power was the third most widely utilized form of renewable energy after hydroelectric power and wind power; in 2022 it accounted for about 4.5 percent of the world’s total power generation capacity. The majority of the world’s solar power comes from solar photovoltaics (solar panels). China has dominated the solar industry, holding more than 37 percent of the global installed capacity of installed photovoltaic capacity in 2022. The United States has the second largest installed capacity, with Japan, Germany, India, Australia, Italy, and Brazil being other major producers.

In a thermoelectric generating system a heat source—usually fueled by coal, oil, or gas—is used within a boiler to convert water to high-pressure steam. The steam expands and turns the blades of a turbine, which turns the armature of a generator, producing electric power. A condenser converts any remaining steam to water, and a pump returns the water to the boiler.

Solar photovoltaics

Solar radiation may be converted directly into electricity by solar cells (photovoltaic cells). In such cells, a small electric voltage is generated when light strikes the junction between a metal and a semiconductor (such as silicon) or the junction between two different semiconductors. (See photovoltaic effect.) The power generated by a single photovoltaic cell is typically only about two watts. By connecting large numbers of individual cells together, however, as in solar panel arrays, hundreds or even thousands of kilowatts of electric power can be generated in a solar electric plant or in a large household array. The energy efficiency of most present-day photovoltaic cells is about 20 percent, and, since the intensity of solar radiation is low to begin with, large and costly assemblies of such cells are usually required to produce even moderate amounts of power.

Solar powerSingle-family house with solar panels on the roof.

Classic crystalline silicon panels and emerging technologies using thin-film solar cells (such as CIGS or cadmium telluride) can be installed by homeowners, businesses, and even power utilities to replace or augment the conventional electric supply. Grid-connected systems integrate solar arrays with public utility power grids in two ways. One-way systems are used by utilities to supplement power grids during midday peak usage. Bidirectional systems are used by companies and individuals to supply some or all of their power needs, with any excess power fed back into a utility power grid. A major advantage of grid-connected systems is that no storage batteries are needed. The corresponding reduction in capital and maintenance costs is usually offset, however, by the increased complexity of the system. Inverters and additional protective gear are needed to interface low-voltage DC output from the solar array with a high-voltage AC power grid. Additionally, rate structures for reverse metering are necessary when residential and industrial solar systems feed energy back into a utility grid. (See also building-integrated photovoltaics.)

(Read Britannica Money’s “How to buy solar panels for your home.”)

Small photovoltaic cells that operate on sunlight or artificial light have found major use in low-power applications—as power sources for calculators and watches, for example. Larger units have been used to provide power for water pumps and communications systems in remote areas and for weather and communications satellites.

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Concentrated solar power

Concentrated solar power plants employ concentrating, or focusing, collectors to concentrate sunlight received from a wide area onto a small blackened receiver, thereby considerably increasing the light’s intensity in order to produce high temperatures. The arrays of carefully aligned mirrors or lenses can focus enough sunlight to heat a target to temperatures of 2,000 °C (3,600 °F) or more. This heat can then be used to operate a boiler, which in turn generates steam for a steam turbine electric generator power plant. For producing steam directly, the movable mirrors can be arranged so as to concentrate large amounts of solar radiation upon blackened pipes through which water is circulated and thereby heated. In 2022 Spain was the largest producer of electricity from concentrated solar power plants, with the United States having the second largest installed capacity. The Ivanpah Solar Electric Generating System is a concentrated solar thermal power plant in the Mojave Desert near the California-Nevada border in the United States and was the largest such plant when it began operating in 2013; larger plants have since been built in Morocco and United Arab Emirates.

Meet the renewables