Solar irradiance - Revision history

Designing Buildings at 06:23, 22 July 2022

2022-07-22T06:23:10Z

← Older revision		Revision as of 06:23, 22 July 2022
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	[[File:Sun_lrg.jpg\|link=File:Sun_lrg.jpg]]		[[File:Sun_lrg.jpg\|link=File:Sun_lrg.jpg]]
		+
		+	= Introduction =

	Solar Irradiance is the power being emitted by a nuclear fusion reaction when protons of hydrogen atoms create helium atoms by violently colliding within the core of the sun. Solar irradiance is measured in watts per square metre (W/m2).		Solar Irradiance is the power being emitted by a nuclear fusion reaction when protons of hydrogen atoms create helium atoms by violently colliding within the core of the sun. Solar irradiance is measured in watts per square metre (W/m2).
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	This power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2). Total solar irradiance is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges.		This power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2). Total solar irradiance is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges.
		+
		+	For more information see: Radiation.

	= Solar irradiance and carbon dioxide =		= Solar irradiance and carbon dioxide =

	Whilst 30% of the solar energy coming from the sun is reflected back into space, the rest is absorbed by the atmosphere or warms the surface of the earth. Some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect'.		Whilst 30% of the solar energy coming from the sun is reflected back into space, the rest is absorbed by the atmosphere or warms the surface of the earth. Some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect'.
		+
		+	For more information see: Greenhouse effect.

	= Solar irradiance and energy =		= Solar irradiance and energy =

Designing Buildings at 06:07, 22 July 2022

2022-07-22T06:07:45Z

← Older revision		Revision as of 06:07, 22 July 2022
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	Whilst 30% of the solar energy coming from the sun is reflected back into space, the rest is absorbed by the atmosphere or warms the surface of the earth. Some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect'.		Whilst 30% of the solar energy coming from the sun is reflected back into space, the rest is absorbed by the atmosphere or warms the surface of the earth. Some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect'.

−	= Solar ~~Irradiance~~ and energy =	+	= Solar irradiance and energy =

	Solar irradiance to cell efficiency, refers to the percentage of solar irradiance that can be turned into useful electrical energy. A standard photovoltaic panel can normally achieve up to 20% (sometimes up to 23%). However in May of 2022 the Fraunhofer Institute for Solar Energy Systems developed the world's most efficient solar cell with 47.6 percent efficiency, under direct sunlight conditions.		Solar irradiance to cell efficiency, refers to the percentage of solar irradiance that can be turned into useful electrical energy. A standard photovoltaic panel can normally achieve up to 20% (sometimes up to 23%). However in May of 2022 the Fraunhofer Institute for Solar Energy Systems developed the world's most efficient solar cell with 47.6 percent efficiency, under direct sunlight conditions.

−	Whilst efficiency at any given point is important, energy is used over longer periods and so the amount of energy on a surface over time as well as how well a solar PV system can convert that to useful electricity for say a year, from both direct an indirect sunlight on cloudy days for instance.	+	Whilst efficiency at any given point is important, energy is used over longer periods and this is dependent on the amount of energy on a surface over time as well as how well a solar PV system can convert that to useful electricity for say a year, from both direct an indirect sunlight on cloudy days for instance.
−		+
−	~~= Solar Irradiation. =~~	+
−		+
−	Solar irradiation is a measure of that energy per unit area Watt hours per metre squared (Wh/m2) relative to a time period Joules per metre square (J/m2). Irradiance is a measure of power on a surface at a given point in time, whilst irradiation measures the amount of energy on a surface area over time.	+

	= Global Horizontal Irradiance (GHI) =		= Global Horizontal Irradiance (GHI) =

−	Global Horizontal Irradiance is a measure of the total, direct and indirect irradiance of the sun on a flat surface of the earth measure, relative to the solar zenith angle Also called solar exposure or insolation it is given as a measure of SI units in Watts per metre square (W/m2). It can be measured using a pyranometer.	+	Global Horizontal Irradiance is a measure of the total, direct and indirect irradiance of the sun on a flat surface of the earth measure, relative to the solar zenith angle. Also called solar exposure or insolation it is given as a measure of SI units in Watts per metre square (W/m2). It can be measured using a pyranometer.

	= Direct Normal Irradiance (DNI) =		= Direct Normal Irradiance (DNI) =

−	Direct Normal Irradiance is the amount of direct power hitting a surface, such as the ~~earth~~ when it is perpendicular to the sun. It excludes the losses likely to occur within the earths atmosphere by absorption and the scattering of radiation via moisture, clouds, ozone etc. It can be measured using a pyrheliometers.	+	Direct Normal Irradiance is the amount of direct power hitting a surface, such as the Earth when it is perpendicular to the sun. It excludes the losses likely to occur within the earths atmosphere by absorption and the scattering of radiation via moisture, clouds, ozone etc. It can be measured using a pyrheliometers.

	= Direct Solar Irradiance (DSI) =		= Direct Solar Irradiance (DSI) =
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	= Diffuse Horizontal Irradiance (DHI) =		= Diffuse Horizontal Irradiance (DHI) =

−	Diffuse ~~horizontal~~ Irradiance is ~~the~~ measure of radiation from all areas reflected within in the atmosphere and ~~exclude~~ radiation coming directly from the sun.	+	Diffuse Horizontal Irradiance is a measure of radiation from all areas reflected within in the atmosphere and excludes radiation coming directly from the sun.

	= Global Tilted Irradiance (GTI) =		= Global Tilted Irradiance (GTI) =
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	Global Tilted Irradiance (GTI) Is the same as Global Horizontal Irradiance and measures the total, direct and indirect irradiance of the sun but on a surface that is at a specified angle, tilt or azimuth. It is often relevant for solar devices that track and move with the sun.		Global Tilted Irradiance (GTI) Is the same as Global Horizontal Irradiance and measures the total, direct and indirect irradiance of the sun but on a surface that is at a specified angle, tilt or azimuth. It is often relevant for solar devices that track and move with the sun.

−	= External ~~References~~ =	+	= External references =
−		+
−	~~[https://education.nationalgeographic.org/resource/solar-energy https://education.nationalgeographic.org/resource/solar-energy]~~	+

−	[https://www.ise.fraunhofer.de/en/press-media/press-releases/2022/fraunhofer-ise-develops-the-worlds-most-efficient-solar-cell-with-47-comma-6-percent-efficiency.html https://www.ise.fraunhofer.de/en/press-media/press-releases/2022/fraunhofer-ise-develops-the-worlds-most-efficient-solar-cell-with-47-comma-6-percent-efficiency.html]	+	* [https://education.nationalgeographic.org/resource/solar-energy https://education.nationalgeographic.org/resource/solar-energy]
		+	* [https://www.ise.fraunhofer.de/en/press-media/press-releases/2022/fraunhofer-ise-develops-the-worlds-most-efficient-solar-cell-with-47-comma-6-percent-efficiency.html https://www.ise.fraunhofer.de/en/press-media/press-releases/2022/fraunhofer-ise-develops-the-worlds-most-efficient-solar-cell-with-47-comma-6-percent-efficiency.html]

	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =
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	* Better prediction of overheating in new homes.		* Better prediction of overheating in new homes.
	* Brise soleil.		* Brise soleil.
−	* Building fabric.
	* Cool roofs.		* Cool roofs.
−	* ~~Designing daylight solutions for commercial buildings.~~	+	* Greenhouse effect.
−	* Emissivity.	+
−	* EN 17037 Daylight in buildings.	+
−	* G-value.	+
	* Large scale solar thermal energy.		* Large scale solar thermal energy.
	* Low-e glass.		* Low-e glass.
−	* Natural ventilation.
−	* Part L.
−	* Passive building design.
	* Shading coefficient.		* Shading coefficient.
−	* Solar chimney.
	* Solar heat gain coefficient.		* Solar heat gain coefficient.
	* Solar photovoltaics.		* Solar photovoltaics.
−	* Solar ~~shading~~.	+	* Solar radiation.
	* Solar thermal panels.		* Solar thermal panels.
−	* Thermal comfort.
−	* Thermal mass
	* Thermal optical properties.		* Thermal optical properties.
−	* Trombe wall.
	* Urban heat island effect.		* Urban heat island effect.
	* Visible light.		* Visible light.

	[[Category:DCN_Definition]] [[Category:DCN_Education_and_Training]] [[Category:DCN_Product_Knowledge]]		[[Category:DCN_Definition]] [[Category:DCN_Education_and_Training]] [[Category:DCN_Product_Knowledge]]

Designing Buildings at 05:57, 22 July 2022

2022-07-22T05:57:07Z

← Older revision		Revision as of 05:57, 22 July 2022
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	[[File:Sun_lrg.jpg\|link=File:Sun_lrg.jpg]]		[[File:Sun_lrg.jpg\|link=File:Sun_lrg.jpg]]

−	Solar Irradiance is the power being emitted by a nuclear fusion reaction when protons of hydrogen atoms create helium atoms by violently colliding ~~with~~ the core of the sun. ~~The solar~~ irradiance is measured in watts per square metre (W/m2) ~~in SI units~~.	+	Solar Irradiance is the power being emitted by a nuclear fusion reaction when protons of hydrogen atoms create helium atoms by violently colliding within the core of the sun. Solar irradiance is measured in watts per square metre (W/m2).

−	The process ~~occuring on~~ the sun is known as a PP (proton-proton) chain reaction or the CNO cycle as it relies on carbon, nitrogen, and oxygen~~, the~~ sun fuses about 620 million metric tons of hydrogen every second. This releases tremendous amounts of energy, heat, and light that flow from the sun as electromagnetic radiation (EMR).	+	The process occurring in the sun is known as a PP (proton-proton) chain reaction or the CNO cycle as it relies on carbon, nitrogen, and oxygen. The sun fuses about 620 million metric tons of hydrogen every second. This releases tremendous amounts of energy, heat, and light that flow from the sun as electromagnetic radiation (EMR).

−	Low frequency infrared waves and the colour spectrum of light are emitted as well as high-frequency waves of Gamma rays, X-rays, and ultraviolet radiation or UV rays, of which the most harmful are absorbed ~~int~~ the atmosphere whilst ~~other~~ fall on the surface and can cause sunburn.	+	Low frequency infrared waves and the colour spectrum of light are emitted as well as high-frequency waves of Gamma rays, X-rays, and ultraviolet radiation or UV rays, of which the most harmful are absorbed into the atmosphere whilst others fall on the surface of the Earth and can cause sunburn.

−	This ~~wave~~ power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2) ~~indicating the~~ solar irradiance~~. Total Solar Irradiance~~ is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges.	+	This power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2). Total solar irradiance is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges.

−	= Solar ~~Irradiance~~ and ~~Carbon Dioxide~~ =	+	= Solar irradiance and carbon dioxide =

−	Whilst 30% of the solar energy coming from the sun is reflected back into space, the rest is absorbed by the atmosphere~~, the remaining radiation~~ warms the surface of the earth ~~(solar irradiance), whilst some~~ infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere.	+	Whilst 30% of the solar energy coming from the sun is reflected back into space, the rest is absorbed by the atmosphere or warms the surface of the earth. Some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect'.
−		+
−	~~As Carbon Dioxide soaks up this infrared energy, it vibrates and re-emits the infrared energy back in all directions~~. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect.	+

	= Solar Irradiance and energy =		= Solar Irradiance and energy =

Editor at 14:45, 20 July 2022

2022-07-20T14:45:30Z

← Older revision		Revision as of 14:45, 20 July 2022
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	= Solar Irradiance and Carbon Dioxide =		= Solar Irradiance and Carbon Dioxide =

−	Whilst 30% of the solar energy is reflected back into space, the rest is absorbed by the atmosphere, the remaining radiation warms the surface of the earth, whilst some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere.	+	Whilst 30% of the solar energy coming from the sun is reflected back into space, the rest is absorbed by the atmosphere, the remaining radiation warms the surface of the earth (solar irradiance), whilst some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere.

	As Carbon Dioxide soaks up this infrared energy, it vibrates and re-emits the infrared energy back in all directions. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect.		As Carbon Dioxide soaks up this infrared energy, it vibrates and re-emits the infrared energy back in all directions. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect.

Editor at 14:44, 20 July 2022

2022-07-20T14:44:08Z

← Older revision		Revision as of 14:44, 20 July 2022
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	This wave power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2) indicating the solar irradiance. Total Solar Irradiance is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges.		This wave power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2) indicating the solar irradiance. Total Solar Irradiance is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges.
		+
		+	= Solar Irradiance and Carbon Dioxide =

	Whilst 30% of the solar energy is reflected back into space, the rest is absorbed by the atmosphere, the remaining radiation warms the surface of the earth, whilst some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere.		Whilst 30% of the solar energy is reflected back into space, the rest is absorbed by the atmosphere, the remaining radiation warms the surface of the earth, whilst some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere.

−	~~Greenhouse gases trap this reflected power back~~ up ~~into the atmosphere. In~~ this ~~way~~, ~~they act like~~ the ~~glass walls of a greenhouse~~. ~~This greenhouse effect keeps the~~ Earth ~~warm enough~~ to ~~sustain life~~.	+	As Carbon Dioxide soaks up this infrared energy, it vibrates and re-emits the infrared energy back in all directions. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the 'greenhouse effect.

	= Solar Irradiance and energy =		= Solar Irradiance and energy =

Editor at 14:40, 20 July 2022

2022-07-20T14:40:26Z

← Older revision		Revision as of 14:40, 20 July 2022
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	[https://education.nationalgeographic.org/resource/solar-energy https://education.nationalgeographic.org/resource/solar-energy]		[https://education.nationalgeographic.org/resource/solar-energy https://education.nationalgeographic.org/resource/solar-energy]
		+
		+	[https://www.ise.fraunhofer.de/en/press-media/press-releases/2022/fraunhofer-ise-develops-the-worlds-most-efficient-solar-cell-with-47-comma-6-percent-efficiency.html https://www.ise.fraunhofer.de/en/press-media/press-releases/2022/fraunhofer-ise-develops-the-worlds-most-efficient-solar-cell-with-47-comma-6-percent-efficiency.html]

	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =

Editor at 14:39, 20 July 2022

2022-07-20T14:39:07Z

← Older revision		Revision as of 14:39, 20 July 2022
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	Global Tilted Irradiance (GTI) Is the same as Global Horizontal Irradiance and measures the total, direct and indirect irradiance of the sun but on a surface that is at a specified angle, tilt or azimuth. It is often relevant for solar devices that track and move with the sun.		Global Tilted Irradiance (GTI) Is the same as Global Horizontal Irradiance and measures the total, direct and indirect irradiance of the sun but on a surface that is at a specified angle, tilt or azimuth. It is often relevant for solar devices that track and move with the sun.
		+
		+	= External References =
		+
		+	[https://education.nationalgeographic.org/resource/solar-energy https://education.nationalgeographic.org/resource/solar-energy]

	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =

Editor at 14:13, 20 July 2022

2022-07-20T14:13:00Z

← Older revision		Revision as of 14:13, 20 July 2022
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	Greenhouse gases trap this reflected power back up into the atmosphere. In this way, they act like the glass walls of a greenhouse. This greenhouse effect keeps the Earth warm enough to sustain life.		Greenhouse gases trap this reflected power back up into the atmosphere. In this way, they act like the glass walls of a greenhouse. This greenhouse effect keeps the Earth warm enough to sustain life.
		+
		+	= Solar Irradiance and energy =

	Solar irradiance to cell efficiency, refers to the percentage of solar irradiance that can be turned into useful electrical energy. A standard photovoltaic panel can normally achieve up to 20% (sometimes up to 23%). However in May of 2022 the Fraunhofer Institute for Solar Energy Systems developed the world's most efficient solar cell with 47.6 percent efficiency, under direct sunlight conditions.		Solar irradiance to cell efficiency, refers to the percentage of solar irradiance that can be turned into useful electrical energy. A standard photovoltaic panel can normally achieve up to 20% (sometimes up to 23%). However in May of 2022 the Fraunhofer Institute for Solar Energy Systems developed the world's most efficient solar cell with 47.6 percent efficiency, under direct sunlight conditions.

Editor at 14:12, 20 July 2022

2022-07-20T14:12:14Z

Editor at 14:11, 20 July 2022

2022-07-20T14:11:18Z

← Older revision		Revision as of 14:11, 20 July 2022
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−	[[File:~~Sun lrg~~.jpg]]	+	[[File:Sun_lrg.jpg\|link=File:Sun_lrg.jpg]]

−	Solar Irradiance is the power being emitted by a nuclear fusion reaction when protons of hydrogen atoms create helium atoms by violently colliding with the core of the sun.	+	Solar Irradiance is the power being emitted by a nuclear fusion reaction when protons of hydrogen atoms create helium atoms by violently colliding with the core of the sun. The solar irradiance is measured in watts per square metre (W/m2) in SI units.

−	The process is known as a PP (proton-proton) chain reaction or the CNO cycle as it relies on carbon, nitrogen, and oxygen, the sun fuses about 620 million metric tons of hydrogen every second. This releases tremendous amounts of energy, heat, and light that flow from the sun as electromagnetic radiation (EMR).	+	The process occuring on the sun is known as a PP (proton-proton) chain reaction or the CNO cycle as it relies on carbon, nitrogen, and oxygen, the sun fuses about 620 million metric tons of hydrogen every second. This releases tremendous amounts of energy, heat, and light that flow from the sun as electromagnetic radiation (EMR).

	Low frequency infrared waves and the colour spectrum of light are emitted as well as high-frequency waves of Gamma rays, X-rays, and ultraviolet radiation or UV rays, of which the most harmful are absorbed int the atmosphere whilst other fall on the surface and can cause sunburn.		Low frequency infrared waves and the colour spectrum of light are emitted as well as high-frequency waves of Gamma rays, X-rays, and ultraviolet radiation or UV rays, of which the most harmful are absorbed int the atmosphere whilst other fall on the surface and can cause sunburn.

−	This wave power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2) indicating the solar irradiance.	+	This wave power at any given point in time is measured relative to a unit area of the surface it is hitting, normally Watts per metre square (Wm2) indicating the solar irradiance. Total Solar Irradiance is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges.

	Whilst 30% of the solar energy is reflected back into space, the rest is absorbed by the atmosphere, the remaining radiation warms the surface of the earth, whilst some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere.		Whilst 30% of the solar energy is reflected back into space, the rest is absorbed by the atmosphere, the remaining radiation warms the surface of the earth, whilst some infrared waves are radiated back into the atmosphere. These waves are intercepted by greenhouse gases, such as water vapour and carbon dioxide as they rise through the atmosphere.
Line 17:		Line 17:
	Whilst efficiency at any given point is important, energy is used over longer periods and so the amount of energy on a surface over time as well as how well a solar PV system can convert that to useful electricity for say a year, from both direct an indirect sunlight on cloudy days for instance.		Whilst efficiency at any given point is important, energy is used over longer periods and so the amount of energy on a surface over time as well as how well a solar PV system can convert that to useful electricity for say a year, from both direct an indirect sunlight on cloudy days for instance.

−	Solar Irradiation.	+	= Solar Irradiation. =

−	Solar irradiation is a measure of that energy per unit area Watt hours per metre squared (Wh/m2) ~~it is sometimes noted~~ relative to a time period ~~to give,~~ Joules per metre square (J/m2). Irradiance is a measure of power on a surface at a given point in time, whilst irradiation measures the amount of energy on a surface area over time.	+	Solar irradiation is a measure of that energy per unit area Watt hours per metre squared (Wh/m2) relative to a time period Joules per metre square (J/m2). Irradiance is a measure of power on a surface at a given point in time, whilst irradiation measures the amount of energy on a surface area over time.
−		+
−	~~Solar Irradiation.~~	+
−		+
−	is the power per unit area received from the Sun in the form of electromagnetic radiation as measured in the wavelength range of the measuring instrument. The solar irradiance is measured in watts per square metre (W/m2) in SI units.	+
−		+
−	~~Total Solar Irradiance is a measure of all possible wavelengths of solar power that enter the earths atmosphere at its upper edges~~.	+

	== Global Horizontal Irradiance (GHI) ==		== Global Horizontal Irradiance (GHI) ==
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	* Urban heat island effect.		* Urban heat island effect.
	* Visible light.		* Visible light.
−
−	~~[[Category:Articles_needing_more_work]]~~

← Older revision		Revision as of 14:12, 20 July 2022
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	Solar irradiation is a measure of that energy per unit area Watt hours per metre squared (Wh/m2) relative to a time period Joules per metre square (J/m2). Irradiance is a measure of power on a surface at a given point in time, whilst irradiation measures the amount of energy on a surface area over time.		Solar irradiation is a measure of that energy per unit area Watt hours per metre squared (Wh/m2) relative to a time period Joules per metre square (J/m2). Irradiance is a measure of power on a surface at a given point in time, whilst irradiation measures the amount of energy on a surface area over time.

−	== Global Horizontal Irradiance (GHI) ==	+	= Global Horizontal Irradiance (GHI) =

	Global Horizontal Irradiance is a measure of the total, direct and indirect irradiance of the sun on a flat surface of the earth measure, relative to the solar zenith angle Also called solar exposure or insolation it is given as a measure of SI units in Watts per metre square (W/m2). It can be measured using a pyranometer.		Global Horizontal Irradiance is a measure of the total, direct and indirect irradiance of the sun on a flat surface of the earth measure, relative to the solar zenith angle Also called solar exposure or insolation it is given as a measure of SI units in Watts per metre square (W/m2). It can be measured using a pyranometer.

−	== Direct Normal Irradiance (DNI) ==	+	= Direct Normal Irradiance (DNI) =

	Direct Normal Irradiance is the amount of direct power hitting a surface, such as the earth when it is perpendicular to the sun. It excludes the losses likely to occur within the earths atmosphere by absorption and the scattering of radiation via moisture, clouds, ozone etc. It can be measured using a pyrheliometers.		Direct Normal Irradiance is the amount of direct power hitting a surface, such as the earth when it is perpendicular to the sun. It excludes the losses likely to occur within the earths atmosphere by absorption and the scattering of radiation via moisture, clouds, ozone etc. It can be measured using a pyrheliometers.

−	== Direct Solar Irradiance (DSI) ==	+	= Direct Solar Irradiance (DSI) =

	Direct Irradiance (DSI) is the irradiance that hits the outmost edge of the earths atmosphere, excluding any diffused by elements in the atmosphere.		Direct Irradiance (DSI) is the irradiance that hits the outmost edge of the earths atmosphere, excluding any diffused by elements in the atmosphere.

−	== Diffuse Horizontal Irradiance (DHI) ==	+	= Diffuse Horizontal Irradiance (DHI) =

	Diffuse horizontal Irradiance is the measure of radiation from all areas reflected within in the atmosphere and exclude radiation coming directly from the sun.		Diffuse horizontal Irradiance is the measure of radiation from all areas reflected within in the atmosphere and exclude radiation coming directly from the sun.
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	* Urban heat island effect.		* Urban heat island effect.
	* Visible light.		* Visible light.
		+
		+	[[Category:DCN_Definition]] [[Category:DCN_Education_and_Training]] [[Category:DCN_Product_Knowledge]]