How much of the Earth's surface would need to be covered in solar panels to provide enough energy for all of humanity and Earth's atmosphere affected by solar energy?
10% of the surface area of the Sahara Desert with 10% efficient solar panels is the number I've heard, but you could easily check this out with a Google search.
A rough theoretical estimation can be done this way. The surface area of the earth is 5x1014 m2. Note that the entire area is not equally illuminated at different times of day and on different days of the season. So, we consider the average irradiation received by the earth as 8 kWh/m2 per day for 365 days; the entire earth receives 40x1014 kWh of sunlight daily, but the energy is distributed in different time zones.
Considering that polycrystalline PV panels have an energy conversion efficiency of 15%, battery or inverter efficiency of 90%, and another loss of 5% in transmission and distribution, we get an overall efficiency of 12.8%. So, we can have 5.12 x 1014 kWh of electricity per day. This translates to 1868.8 x 1014 kWh per year.
The world's electrical energy consumption was 25530 TWh in 2022. (1 TWh = 109 kWh). So, 0.25530 x 1014 kWh of electricity is needed per year.
So, the electricity generated by solar PV panels covering the entire earth (including oceans) is 7316 times more than what we need in the form of electricity.
To meet the yearly electricity consumption of Earth 0.25530 x 1014 kWh, the area covered with PV panels should be 1/7316th of Earth's area. That is 683.4 x 108 m2 or nearly 68,340 km2. This is roughly 20% of India's area. 0.75% of the Sahara desert's area, provided we get 8 kWh/m2 irradiation daily.
Many assumptions and simplifications are taken here -
1. If we consider this like a solar farm, the PV panels will not be densely packed. Considering the spacing between PV panel rows, the required area can be 2 or 3 times the calculated area. The required area also depends on actual irradiation received and losses in electrical parts
2. We have ignored the efficiency loss due to the temperature rise of the PV panels; we have not considered the loss due to dust deposition, clouds, and other types of shading on the panels, etc. At 1 degree Celsius temperature rise from standard test conditions, the PV cell has a reduction in efficiency by nearly 0.45%
2. We have not considered our other energy consumptions (petroleum, coal, natural gas), etc. The world's energy requirement is 580 million terajoules (1 TJ = 277777.78 kWh). This is 1.6124 x 1014 kWh. If every energy consumption is electrified, the area requirement for the giant PV farm will be higher (6 times).
So, for a more realistic, rough estimation, the proposed PV farm may be 10-12 times higher than the previous calculation if we consider spacings in PV panels (2x), and we want all the energy sources to be replaced by electricity only (5x or 6x). This value is close to the previous answer by Dr Cordner Peacock (10% of Sahara desserts area if 10% efficient PV panels are used)
This page has some similar discussions. Pen State University. https://www.e-education.psu.edu/earth104/node/950
Now, many such solar panels are connected in series in a form of solar string to get required voltage. Also, many such identical solar strings are connected in parallel to get the required current. Hence, in this way we get the required amount of energy by connecting solar panels. The radiation warms Earth's surface, and the surface radiates some of the energy back out in the form of infrared waves. As they rise through the atmosphere, they are intercepted by greenhouse gases, such as water vapor and carbon dioxide. Greenhouse gases trap the heat that reflects back up into the atmosphere.Total surface area of the earth required to produce enough power through solar alone is not as much as you might think. By one estimate it would require an area of 496,805 square kilometers. Dividing the global yearly demand by 400 kW•h per square meter (198,721,800,000,000 / 400) and we arrive at 496,804,500,000 square meters or 496,805 square kilometers (191,817 square miles) as the area required to power the world with solar panels. Solar power is more powerful than many people realize. If there were 3.5 hours of sunlight daily, the world would need 18.54 TW of solar power. Assuming the solar panels are rated at 350W, the world would need roughly 51.428 billion solar panels. Additionally, if 4 acres can accommodate a 1MW plant, 74.16 million acres of land would be required to power the planet. The atmosphere absorbs 23 percent of incoming sunlight while the surface absorbs 48. The atmosphere radiates heat equivalent to 59 percent of incoming sunlight; the surface radiates only 12 percent. In other words, most solar heating happens at the surface, while most radioactive cooling happens in the atmosphere. Without the Earth's rotation, tilt relative to the sun, and surface water, global circulation would be simple. With the Sun directly over the equator, the ground and atmosphere there would heat up more than the rest of the planet. This region would become very hot, with hot air rising into the upper atmosphere.
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