The first solar panels in space were launched aboard the Vanguard 1 satellite in 1958. This was the first real application of solar panels before we started using them as an energy source for commercial and residential buildings.
The idea of capturing solar energy in space and using it on Earth has been around since the beginning of the space age. The idea has continued to slowly gather steam as the supporting technology improves enough to make the idea a reality.
The reason for this growing interest is that solar panels work far much better in space than they do on Earth. In this article, we will look at what Space-Based Solar is and how solar panels work better in space.
Are Solar Panels More Effective in Space?
Solar panels produce more energy in space than they do on Earth. The energy produced by Space-Based solar far exceeds all other methods combined of producing energy on Earth while having almost zero negative effect on the environment.
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Space-based solar is a possible avenue for solving the problems of greenhouse gas emissions and the energy deficit.
What is Space-Based Solar Power?
Satellites equipped with reflectors, solar panels, and either a microwave or laser transmitter are launched into space. The reflectors direct solar radiation onto the solar panels which convert it into a microwave or laser before wirelessly beaming it to Earth.
The energy is received on Earth at a power receiving station before being sent for use to the grid. The two leading technologies for Space-Based Solar Power or SBSP are microwave transmitting satellites and laser transmitting satellites.
Microwave Transmitting Satellites
Microwave transmitting satellites orbit 21,750 miles above the Earth. Microwave transmitters are huge. The solar reflectors span 1,8 miles and weigh over 80,000 metric tons. They could generate gigawatts of power. Enough energy for a major U.S city.
The downside of microwave transmitting satellites is the cost to build, launch and maintain them which runs into the tens of billions of dollars. The receiving satellites on Earth also take up a massive amount of land, between 2 to 6 miles, which is expensive to purchase and develop.
Laser Transmitting Satellites
Laser transmitting satellites are closer, orbiting at 250 miles above the Earth. They weigh less than 10 metric tons and are drastically cheaper to build. They cost nearly $500 million to launch and run. At only 2 meters in diameter, they are also smaller.
While they are smaller in size and cheaper to operate this does come at a cost. They produce far less energy of about 1 to 10 megawatts than microwave transmitters. There is also a fear that lasers could be used for military purposes.
These technologies are still largely in the research and developmental phase. They could however come into play in the years to come as the technology to make this happen already exists. (Source)
Why Do Solar Cells Work so Well in Space?
Solar panels in space are exposed to and therefore absorb more solar radiation. Some of that solar radiation is lost before it reaches the solar panels on Earth. Up to 30% is lost before it reaches Earth due to the atmosphere, cloud cover, seasonality, and of course night. None of these affect solar panels in space.
Conventional versus space solar panels
Both conventional solar and space solar panels are made from silicon and fit into arrays. That is where the similarities end, however. Space solar panels are built to withstand the extreme conditions of cold, heat, and radiation in space. (Source)
There are no clouds, atmosphere, or night in space. There is sunlight 24-hours a day, 99% of the year. The absence of night and day means solar panels in space produce more energy. Space-based solar panels produce up to 2,000 gigawatts of continuous energy. This is 40 times more than what terrestrial solar panels produce.
Between 55 to 60% of solar energy is reflected or absorbed by gases, clouds, and dust before it can reach Earth’s surface.
The reduced solar radiation means solar panels on Earth produce less energy. Furthermore, they don’t produce any energy at night.
Space solar panels also don’t need to convert DC power to AC power like conventional solar panels. This creates a more efficient energy transfer as there is no energy loss through conversion.
What Type of Solar Panels Are Used in Space?
Solar panels used in space are made from either silicon cells covered in thin glass or cells made from gallium arsenide and other similar materials. Gallium arsenide solar panels are the more efficient solar cell.
The glass-covered silicon cells are similar to conventional solar panels, except they are made much stronger to resist radiation and the extreme temperatures in space. These are the solar panels used on the International Space Station, which has most of the solar panels in space.
Gallium arsenide solar panels have an efficiency of 34%. In contrast, the most efficient commercial solar panels on Earth have a maximum efficiency of 22.8%. (Source)
There is however research into a new type of solar cell that reportedly reaches an efficiency of over 25%.
How Long Do Solar Panels Last in Space? Degradation Pace
Solar panels in space have a reduced lifespan as they are exposed to a harsher environment compared to terrestrial solar panels. The effect of extreme heat, cold, and radiation increases the cell degradation of solar panels in space up to 8 times faster than solar panels on Earth.
The main reason for the increased cell degradation in space is damage caused by the irradiation of high-energy particles. The particles include electrons and protons from the earth’s radiation belt, along with solar cosmic rays.
The collision of these high-energy particles with cell materials causes the lattice atoms to shift positions decreasing the lifespan of the photo-generated carriers. (Source)
At present space-based solar is still a far-off concept. The main obstacle is the expense. It is up to 100 times more expensive than utility power. The biggest contributor to the cost is launching solar panels into space.
It also costs too much to launch the additional materials required. It also requires multiple launches and space shuttles can only be used once.