Home Discussion Forum How much more solar energy is there in space than on Earth?

# How much more solar energy is there in space than on Earth?

By space i mean in Earth orbit. How much more electricity would a solar panel generate in orbit rather than the same solar panel on Earth?

1. Think about how big the sun is and how small the earth is, not to mention how far the earth is from the sun. I don’t have an exact number but it would be many decimal places of a percent, like 0.0000001%, but probably even much less than that.

2. Comparing two specific points, one inside Earth’s atmosphere and one outside of it,
the inside point would have much less solar energy than the outside point because the Earth’s atmosphere reflects a high percentage of the sun’s rays.

3. It depends on how you measure it.
At Earth’s orbital radius, sunlight has an intensity of about 1370 W/m^2. So, a solar panel pointed directly at the Sun would receive that much power (simply multiply the intensity by the panel area). A panel tilted somewhat away from the Sun would receive less radiation, of course.
On the ground, with the Sun directly overhead, a solar panel on the ground receives a lower intensity, about 1000 W/m^2. The average during the day is even lower, because the sunlight must travel through more atmosphere when the Sun isn’t directly overhead.

4. Much. You see, since the Earth has a magnetic field, the particles from the solar wind are evaded and spread until they hit the region called the heliopause. The Sun’s energy is supposed to be the greatest energy in the solar system, and there’s way more than there can be measured. The dangerous solar wind particles and UV radiation from the Sun are one reason why you need a spacesuit before travelling in outer space.

5. How much electricity a solar array produces is a bit tougher to predict, since this is not constant. The effectivity of a solar array depends not only on the incidence angle, but also temperature – which can have some effects in space. The higher the substrate temperature of the photo-voltaic cell, the less radiation it converts into electricity. Also solar arrays age quickly in space, producing significant less power after some years.
You can say of the 1370 W/mÃ‚Â² that the sun sends to Earth as radiation, and which you get in Earth orbit as well, only about 20%-30% are converted to electricity by a solar array.
Of the 1370 W/mÃ‚Â² that reach Earth, only about 800-1000W reach the surface of Earth. While the temperatures and cooling by the surrounding air ensures that solar arrays on Earth don’t loose much effectivity, the power output will still be much lower.
In very rough numbers, assuming pretty good solar arrays without active cooling: A solar array that produces 1000W on Earth, would produce about 1250W in space, so about 25% more.
With active cooling, like the secondary solar arrays of the Solar Probe Plus will use, you can make the array about 15% more effective at the same radiation flux.

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