Solar energy

Solar energy is electromagnetic radiation emitted by the Sunsun that can be harnessed using a range of technologies. In total, 173,000 terawatts (trillion watts) of solar energy continuously strikes the Earth. Estimates by the US Department of Energy state the amount of sunlight hitting the Earth's surface in an hour and a half is enough to handle the world's energy consumption for a full year.

As much as 54% percent of incoming sunlight reaching the Earth is absorbed or reflected by the Earth's atmosphere. Of the light that strikes the surface, 50% percent is in the visible spectrum, 45% percent is infrared (IR) radiation, withand the remainder is made of small amounts of (UV) and other forms of electromagnetic radiation.

Solar technologies can harness this energy for a range of uses, including generating electricity, providing light or a comfortable interior environment, and heating water for domestic, commercial, or industrial use. The following are the three main technologies harnessing solar energy are:

• Photovoltaics (PV)—the direct conversion of light into electricity using semiconductors commonly through solar panels.
• Concentrating solar power (CSP)—the use of mirrors to reflect and concentrate sunlight to heat fluid in a receiver in order to generate electricity.
• Solar heating and cooling—the use of solar energy for direct space or water heating without electricity generation.

In 2020, the global cumulative solar PV capacity reached 773.2 gigawatts, an increase of 138 gigawatts of new PV capacity compared to the year before. In 2021 23.6 GW_dc of solar PV capacity was installed in the US, bringing the total capacity to 121.4 GW_dc - enough to power 23.3 million American homes. This increase accounts for 46% of all new electricity-generating capacity added in the US in 2021, the third year in a row that solar has made up the largest share of new electricity generating capacity. In 2021, 3.9% of all US electricity generation came from solar energy.

In 2020, the global cumulative solar PV capacity reached 773.2 gigawatts, an increase of 138 gigawatts of new PV capacity compared with the year before. In 2021, 23.6 GW_dc of solar PV capacity was installed in the US, bringing the total capacity to 121.4 GW_dc—enough to power 23.3 million American homes. This increase accounts for 46 percent of all new electricity-generating capacity added in the US in 2021, the third year in a row that solar has made up the largest share of new electricity generating capacity. In 2021, 3.9 percent of all US electricity generation came from solar energy.

Solar energy is electromagnetic radiation emitted by the Sun that can be harnessed using a range of technologies. In total 173,000 terawatts (trillion watts) of solar energy continuously strikes the Earth. Estimates by the US Department of Energy state the amount of sunlight hitting the Earth's surface in an hour and a half is enough to handle the world's energy consumption for a full year.

As much as 54% of incoming sunlight reaching the Earth is absorbed or reflected by the Earth's atmosphere. Of the light that strikes the surface, 50% is in the visible spectrum, 45% is infrared (IR) radiation with the remainder made of small amounts of (UV) and other forms of electromagnetic radiation.

Diagram showing the interaction of solar energy with the Earth.

Solar technologies can harness this energy for a range of uses, including generating electricity, providing light or a comfortable interior environment, and heating water for domestic, commercial, or industrial use. The three main technologies harnessing solar energy are:

• Photovoltaics (PV)—the direct conversion of light into electricity using semiconductors commonly through solar panels.
• Concentrating solar power (CSP)—the use of mirrors to reflect and concentrate sunlight to heat fluid in a receiver in order to generate electricity.
• Solar heating and cooling—the use of solar energy for direct space or water heating without electricity generation.

In 2020, the global cumulative solar PV capacity reached 773.2 gigawatts, an increase of 138 gigawatts of new PV capacity compared to the year before. In 2021 23.6 GW_dc of solar PV capacity was installed in the US, bringing the total capacity to 121.4 GW_dc - enough to power 23.3 million American homes. This increase accounts for 46% of all new electricity-generating capacity added in the US in 2021, the third year in a row that solar has made up the largest share of new electricity generating capacity. In 2021, 3.9% of all US electricity generation came from solar energy.

It is an essential source of renewable energy, and its technologies are broadly characterized as either passive solar or active solar depending on how they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power, and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air.

The large magnitude of solar energy available makes it a highly appealing source of electricity. Solar energy has been cheaper than fossil fuels since 2021.

In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries' energy security through reliance on an indigenous, inexhaustible, and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating global warming .... These advantages are global.".

It is an essential source of renewable energy, and its technologies are broadly characterized as either passive solar or active solar depending on how they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power, and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air.

The large magnitude of solar energy available makes it a highly appealing source of electricity. Solar energy has been cheaper than fossil fuels since 2021.

In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries' energy security through reliance on an indigenous, inexhaustible, and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating global warming .... These advantages are global.".