Saturday, September 7, 2024

# How Much Solar Energy Hits The Earth Per Square Meter

## How Much Solar Energy Is Received By The Earth Per Square Meter

Estimate the Entropy created in 1 year by the flow of solar heat onto a square meter of earth 3-13

How much solar energy is received by the earth per square meter.

1.4 KW solar energy is received by the earth per square kilo meter.

The Earth receives 174 petawatts of incoming solar radiation at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses.Even if we use 5% of this energy, it is more than 50 times our requirement. The total solar radiation absorbed by the earth and its atmosphere is 3.8 X 1024 Joules/year.This is called diffuse solar radiation. The solar radiation that reaches the Earth’s surface without being diffused is called direct beam solar radiation. The sum of the diffuse and direct solar radiation is called global solar radiation.

Different parts of Earth’s surface receive different amounts of sunlight . The Sun’s rays strike Earth’s surface most directly at the Equator.The three relevant bands, or ranges, along the solar radiation spectrum are ultraviolet, visible , and infrared. Of the light that reaches Earth’s surface, infrared radiation makes up 49.4% of while visible light provides 42.3%So not only are there the obvious intensity changes in ground solar radiation level during the day, going to zero at night, but the spectrum of the radiation changes through each day because of the changing absorption and scattering path length.

## Americas Solar Energy Potential

Every hour, the sun radiates more energy onto the earth than the entire human population uses in one whole year.

The technology required to harness the power of the sun is available now. Solar power alone could provide all of the energy Americans consume there is no shortage of solar energy. The following paragraphs will give you the information you need to prove this to yourself and others. You do not need advanced math skills to follow and perform the arithmetic examples shown below. Anyone who can balance a checkbook or calculate the total square feet of floor space in his or her home, and understand why an area measuring 10 yards by 10 yards equals 100 square yards, can perform the following arithmetic examples and prove that American energy independence could be achieved with solar energy alone.

Science tells us that every square meter of the earths surface, when exposed to direct sunlight, receives about 1000 watts of energy from the suns light. Depending on the angle of sunlight, which changes with the time of day, and the geographical location , the power of the suns light will be somewhat more or less than 1 kilowatt-hour per hour for every square meter of the earths surface exposed to the sun.

Americans can assume, at least in the Sunbelt regions of the southwestern United States, that every square yard of land exposed to direct sunlight will receive about 5 kilowatt-hours per day of solar energy.

What does this mean?

## The Facts Behind This Amazing Statistic

The Sun generates energy by nuclear reactions which occur at its dense hot core .It produces a massive 382.8 trillion trillion watts of electromagnetic radiation mostly in the form of visible light, infrared and ultraviolet. As you get further from the Sun, the intensity, which is power per unit area falls as the square of the distance

The solar constantis the average intensity of the Suns radiation at a distance of 1 astronomical unit . It has a value of 1,361 watts per square metre . In fact, the output of the Sun is variable and fluctuates by 0.1% around this value.

The total energy hitting the Earth in one hour is

solar constant x surface area of Earth-sized disc

1 361 W/m2 x 1.2748 x 1014 m2 = 1.73 x 1017 watt-hours.

This is often expressed as 173,000 terawatt hours , where 1 terawatt is 1 trillion watts

The total energy consumed by humanity in 2017 is slightly less than this at 160,000 TWh . This figure includes not just energy used to generate electricity, but also energy used:

• directly for heating ,
• for transport and
• energy used in industrial processes.

The total amount of electricity consumed in 2017 was approximately 22,000 TWh.

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## Spectral Composition Of Sunlight At Earth’s Surface

The Sun may be said to illuminate, which is a measure of the light within a specific sensitivity range. Many animals have a sensitivity range of approximately 400â700 nm, and given optimal conditions the absorption and scattering by Earth’s atmosphere produces illumination that approximates an equal-energy illuminant for most of this range. The useful range for color vision in humans, for example, is approximately 450â650 nm. Aside from effects that arise at sunset and sunrise, the spectral composition changes primarily in respect to how directly sunlight is able to illuminate. When illumination is indirect, Rayleigh scattering in the upper atmosphere will lead blue wavelengths to dominate. Water vapour in the lower atmosphere produces further scattering and ozone, dust and water particles will also absorb particular wavelengths.

## How Much Solar Energy Per Square Foot Hits The Earth

Solar energy results when you convert sunshine to power but how much solar energy per square foot hits the earth? This is part of the discussion when considering whether solar energy can be used to replace the traditional energy sources we are accustomed to.

Of course, the other part of the question is how much of that solar energy can we capture, convert to power and use?

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Average annual solar radiation arriving at the top of the Earth’s atmosphere is roughly 1361 W/m2. The Sun’s rays are attenuated as they pass through the atmosphere, leaving maximum normal surface irradiance at approximately 1000 W/m2 at sea level on a clear day. When 1361 W/m2 is arriving above the atmosphere , direct sun is about 1050 W/m2, and global radiation on a horizontal surface at ground level is about 1120 W/m2.The latter figure includes radiation scattered or reemitted by the atmosphere and surroundings. The actual figure varies with the Sun’s angle and atmospheric circumstances. Ignoring clouds, the daily average insolation for the Earth is approximately 6 kWh/m2 = 21.6 MJ/m2.

The output of, for example, a panel, partly depends on the angle of the sun relative to the panel. One Sun is a unit of power flux, not a standard value for actual insolation. Sometimes this unit is referred to as a Sol, not to be confused with a sol, meaning one solar day.

## Energy From Sun To Earth

The Sun is generally considered to produce a constant amount of power with a surface intensity of 6.33 \times 10^7 \frac , expressed in units of power per unit area. As the Sun’s rays spread into space this radiation becomes less and less intense as an inverse square law. The average radiation intensity that hits the edge of the Earth’s atmosphere is known as the solar constant, or I_. Although this value is called a constant it varies by about 7% between January 4th , when the Earth is closest to the sun, and July 4th , when the Earth is furthest away. Therefore a yearly average is used and is determined to be 1367 \frac. To determine this value from solar flux, the distance from the Earth to the Sun is used. As well, the total solar flux – not solar flux per unit area – must be determined. Then the total solar flux from the Sun is divided by the surface area of a sphere that has a radius equal to the distance from the Earth to the Sun. This accounts for the “spreading” of the solar energy. The expression to determine this value is:

To determine the average amount of solar energy that reaches the Earth, we must consider what the Earth “looks like” to the Sun. When looking at Earth from the Sun, only one half of the Earth can be seen. Thus to make an appropriate estimate of the average amount of solar energy over the entire surface area of the Earth the value for I_ must be divided by 2.

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## Acs Climate Science Toolkit

Although much hotter on the inside, we can closely approximate the surface of the sun, from which its emission occurs, as a black body at a temperature of about 5800 K. The Stefan-Boltzmann equation then gives the energy flux emitted at the suns surface.

SS = 4 = 63 × 106 W·m2

The surface area of a sphere with a radius r is 4r2. If rS is the radius of the Sun, the total energy it emits is SS4rs2. As the radiation is emitted from this spherical surface, it is spread over larger and larger spherical surfaces, so the energy per square meter decreases, as illustrated schematically in the diagram below.

The figure at the right compares the experimental solar emission curve observed outside the Earths atmosphere to the emission curve for a 5800 K black body located at the suns distance from the Earth. The structure in the experimental curve is a result of absorption of some wavelengths by atoms and ions in the cooler layers outside the suns emitting surface.

When the energy emitted by the sun reaches the orbit of a planet, the large spherical surface over which the energy is spread has a radius, dP, equal to the distance from the sun to the planet. The energy flux at any place on this surface, SP, is less than what it was at the Suns surface. But the total energy spread over this large surface is the same as the total energy that left the sun, so we can equate them:

SS4rs2 = SP4dP2

SP = SS2

## How Much Of The Sun’s Energy Reaches Earth

What is solar energy?

4.9/5energysunreach EarthSun’senergyreachesEarthenergyreach EarthEarth

approximately 1,000 W/m2

One may also ask, how much energy hits the earth every second from the sun? The total solar energy per second on a surface perpendicular to the Sun is about 1350 Joules per square meter or about 0.275 watt-hours. Taking into account incidence angle and the surface area, the effective energy arriving at the Earth is about 1.75E17 Joules per second. A lot of that is reflected away from clouds.

Additionally, how does the sun’s energy reaches the earth?

When the Sun’s energy moves through space, it reaches Earth’s atmosphere and finally the surface. This radiant solar energy warms the atmosphere and becomes heat energy. This heat energy is transferred throughout the planet’s systems in three ways: by radiation, conduction, and convection.

How much solar energy reaches Earth on a cloudless day?

On a cloudless day, each square meter of Earth’s surface is bombarded with about one kilowatt of energy in a single hour of sunlight. Put another way, the amount of solar energy that hits the surface of the earth in one hour is greater than the total amount of energy that the entire human population requires in a year.

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## In Our Learn Solar Series We Answer Some Of The Big Questions About Solar Clarifying A Topic That’s Often Difficult To Understand And Riddled With Misinformation

In our first post, we investigate how much power the sun gives us, then calculate that as a unit of energy. In future posts we’ll look at how this stacks up against our energy needs.

Throughout this series we borrow and expand upon a series of calculations made by Cambridge scholar, David JC MacKay, in his book, “Sustainable Energy Without the Hot Air”. and explore MacKay’s calculations in more detail.

So let’s begin.

As stars go, our sun is pretty average, but at 1.3 million times the size of earth, it’s by far the largest body in the solar system.

Its enormous power comes from nuclear fusion the process of smashing atoms together so hard they “fuse” to form heavier atoms, releasing loads of energy. In our sun’s core, hydrogen is turned to helium, and as you can imagine, it’s desperately hot, burning at around 15.6 million °C.

Earth next to a coronal mass ejection , to scale. CMEs occur due to changes in the corona’s magnetic field , which flings out large amounts of energy and solar material.

Despite feeling the sun’s warmth on our bodies, it’s incredibly far away. The exact distance changes with the earth’s orbit, but the average is 93 million miles , or one Astronomical Unit .

It’s no surprise, therefore, that the sun is an incredible source of power. The top of earth’s atmosphere receives around 1,366 W/m² .

With such extraordinary and practically limitless power, we could easily supply the UK’s electricity needs, now and in the future.

Let’s explore point 1.

## Calculation Of The Area For The Earth And The Uk To Generate All Energy Needs By Solar Panels

Note to calculation: In any large structure which generates solar electricity there must be gaps between the solar panels. In these calculations I have assumed that one sixth of the area of a solar farm/large array of solar panels is not covered by panels.

#### Calculation for the UK

For the UK, since it is a long way from the equator, there is large difference in the solar irradiance between the winter and the summer months. For a location near Manchester in Northern England the solar irradiance is around 300 W/m2 in in the middle of June but in December it is roughly ten times lower.

In the over simplistic calculation below, it has been assumed that the surplus energy generated in the summer months can be efficiently stored to be consumed in the winter months. In reality we are long way from be able to do this!

Data from Science Direct and Enerdata

References

Enerdata Global energy statistical yearbook 2018, Available at: .

Our world in data Global renewable energy consumption over the long-run, Available at: .

Science Direct The UK solar energy resource and the impact of climate change, Available at: .

Williams, D. R. NASA Sun fact sheet, Available at: .

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## Does Ball Lightning Exist

It is in general described as a luminous sphere, most often the size of a small childs head. It appears usually during thunderstorms, sometimes within a few seconds of lightning but sometimes without apparent connection to a lightning bolt. In some cases, ball lightning appears after a thunderstormor even before it.

## Rough Estimates Of The Solar Energy Available At The Earths Surface

The solar constant is the average extraterrestrial insolation at the edge of the atmosphere:

The Earth presents a disc of area nR2 to the Sun, therefore the total amount of extraterrestrial insolation incident on the Earth is ISC × nR2. This value is then divided by half the surface areas of the Earth, 4nR2/2, which gives 684 W/m2, the average insolation incident on unit area of the Earth facing the Sun . Note that solar panels are calibrated assuming that there is 1000 W/m2 available.

A rough estimate of the irradiation incident per unit area of the Earths surface can be made if we assume that 30% of the Suns energy is lost in the atmosphere and that the a day is an average of 12 hours long at any location.

Or if we assume that the Sun is only at an appreciable strength for an average 6 hours in the day :

Figure 2.10 shows the yearly profile of mean solar radiation for different locations around the world. The solid grey line show the value of 5.75 kWh/day and the dashed grey line shows 2.88 kWh/day.

Figure 2.10: The yearly profile of mean solar radiation for different locations around the world.

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## Components Of A Residential Solar Power System

There are a few key components for every solar installation: solar panels, inverter, racking system, cables, monitoring system and increasingly, battery storage system. Other important components that are sometimes overlooked are your existing electric panel and electricity meter because these may need to be updated if they are very old.

## The Future Of Solar Energy

Solar energy has started to grow but until the costs are substantially reduced it will remain a very small component of the world and the U.S. energy picture. Even though the cost has been substantially reduced over the past 50 years, it still remains a very expensive energy source. The PV effect has been known since 1839 and, despite extensive research efforts since then, solar power is still very expensive. It does not seem likely that further research efforts will make the breakthroughs that will lead to the commercialization of solar power in the foreseeable future. There is a lot of solar power waiting to be harnessed if such a breakthrough could be made however, even if there was a way to make solar power viable, it is to be expected that this cannot be done without having a significant impact on the environment.

Paul Breeze, in, 2019

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## Solar Energy To The Earth

Almost all of the Earth‘s energy input comes from the sun. Not all of the sunlight that strikes the top of the atmosphere is converted into energy at the surface of the Earth. The Solar energy to the Earth refers to this energy that hits the surface of the Earth itself. The amount of energy that reaches the the Earth provides a useful understanding of the energy for the Earth as a system. This energy goes towards weather, keeping the temperature of the Earth at a suitable level for life, and powers the entire biosphere. Additionally, this solar energy can be used for solar power either with solar thermal power plants or .

## The Atmosphere And Air Mass

What is Solar Energy?

The atmosphere scatters and absorbs some of the Suns energy that is incident on the Earths surface. Scattering of radiation by gaseous molecules , that are a lot smaller than the wavelengths of the radiation, is called Rayleigh scattering. Roughly half of the radiation that is scattered is lost to outer space, the remaining half is directed towards the Earths surface from all directions as diffuse radiation. Because of absorption by oxygen and ozone molecules the shortest wavelength that reaches the Earths surface is approximately 0.29 µm. Other gas molecules absorbed difference wavelengths as indicated in figure 2.6.

Figure 2.6: The extraterrestrial solar spectrum , the theoretical black body curve and the solar spectrum at the Earth’s surface for AM = 2 and the absorbed regions shown in black.

Scattering by dust particles larger than wavelengths of light is called Mie scattering. This process includes both true scattering and absorption followed by emission, which heats the particles. The amount of radiation scattered by this process will vary a lot depending on location and the weather blowing particles about. A form of Mie scattering called the Tyndall effect, that preferentially scatters shorter wavelengths is responsible for the sky being blue.

Clouds reflect a lot of radiation and also absorbed a little, the rest is transmitted through. Globally, clouds reflect a lot of radiation and help regulate the surface temperature.

For angles Z< 70°:

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