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9 

 

 

 

Review 

Solar power satellites: technical challenges and 

economic feasibility  
Gerardo Antonio Urdaneta*, Christopher Meyers, Lauren Rogalski  

Department of Mechanical Engineering, Arkansas Tech University, 1811 N Boulder Ave, Russellville, AR, 72801, USA 

A R T I C L E   I N F O 
 

Article history: 
Received  24 March 2022  
Received in revised form 
25 April 2022 
Accepted  30 April 2022 
 
Keywords: 
Solar Power, Microwave Transmission,  
Specific Impulse, Low Earth Orbit (LEO) 
 
 
*Corresponding author 
Email address:  
gerar4406@gmail.com 
 
 
DOI: 10.55670/fpll.fuen.1.2.3 

A B S T R A C T 
 

World energy consumption is constantly rising; therefore, it is essential to 
investigate different possibilities to produce power in the medium and long 
term. The sun is a clean source of power that is virtually inexhaustible. 
Photovoltaic (PV) power stations are used to harness this energy, but they are 
not completely reliable since they depend on weather patterns. To overcome 
this problem, large satellites with extensive solar panel surfaces can be placed 
in orbit. These satellites, known as Solar Power Satellites (SPS), would be 
positioned in geostationary orbit (GEO) thus constantly providing energy while 
avoiding meteorological conditions and erosive factors. These benefits make 
solar power station an appealing option for the energy of the future. Therefore, 
in this paper, the possibility and challenges of using solar-powered satellites are 
explored. The mechanisms regarding microwave transmission, photovoltaic 
collection, radiation impact, and propulsion are discussed. The advantages and 
disadvantages of solar-powered satellites are discussed regarding cost and 
practicality, and the current race between different countries to achieve this 
technology was examined. It was found that power could be collected with an 
efficiency of over 30% using gallium-arsenide photovoltaic cells. To minimize 
radiation effects, the use of a 100-micron transparent Pilkington Borosilicate 
Glass (commercially known as CMG cover glass) could be employed. For 
spacecraft propulsion, Hall thrusters provide the optimal combination between 
efficiency and thrust. Finally, the cost analysis indicates that to make the SPS 
viable, launch costs to GEO must be decreased by a factor of 10, solar panel 
efficiency must be increased to 40%, panel density must be minimized, and 
international cooperation must be achieved. 

 
 

 
1. Introduction  

Solar Power Satellites (SPS) are being looked at not only 
as sources of energy on earth but also as an incentive to 
reduce the size and launch costs of satellites [1]. Today’s 
world is currently suffering from increased consumption of 
its resources. With such increasing demand, it is necessary to 
begin exploring other energy sources. There are three main 
reasons for this drive for new and more reliable resources, 
such as the fluctuation of the petroleum industry peaking, the 
fuel-derived greenhouse gas effect, and in general, growing 
global demand for energy. SPS collect the solar radiation in 
space and transmit it using a microwave energy beam to a 
receiving antenna on earth which transforms it into 
electricity [2]. When it comes to solar-powered satellites, 
there are many benefits over other traditional forms of power 
supply. SPS is not affected by the weather or the earth’s 
atmosphere. This allows SPS systems to be set in the most 
optimal path for solar and energy absorption. On the earth’s 

surface, the average solar power per unit area is 250 W/m2 
whereas in space is 1366 W/m2 [3]. Unlike terrestrial solar 
power, solar power in space does not need to be stored 
anywhere in case of drastic weather. Furthermore, the space 
vacuum superconductor property for electromagnetic energy 
transmission is an important benefit over transmission 
systems on earth. Energy is constantly lost in transmission 
grids due to electric resistance, whereas it is completely 
conserved in space. Using SPS’ is not directly harmful to the 
environment, given that there are no carbon dioxide 
emissions produced, so it is a clean and safe energy source [4]. 
SPS could be potentially better than ground-based 
photovoltaic (PV) solar power because of the space's virtually 
unlimited power availability and lower transmission losses 
[5]. Solar radiation can be more easily accumulated in space 
than on earth, and it is constantly available [6]. The Japan 
Aerospace Exploration Agency (JAXA) has made recent 
progress toward the solar space station, which developed a 

 

 

Future Energy 

Open Access Journal 

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August 2022| Volume 01 | Issue 02 | Pages 09-16 

Journal homepage: https://fupubco.com/fuen 

 
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G.A. Urdaneta et al. /Future Energy                                                                                           August 2022| Volume 01 | Issue 02 | Pages 09-16 

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technological map that shows a 1 GW commercial system by 
2030 [5]. Other efforts are located in the ongoing conferences 
about SPS and wireless power transmission (WPT) and an 
evaluation by the International Academy of Astronautics 
(IAA) [7]. If accidents happened in space, they would not be 
as harmful on earth. It must be noted that the cost of this type 
of power generation is high, and there is a concern about 
environmental issues as they relate to the power 
transmission and launch emissions. The benefits of SPS are a 
6-fold increase in available power, longer useful life 
compared to terrestrial PV systems, and no necessity for 
energy storage which in conventional systems causes losses 
up to 40% [8–10]. Space-based solar power consists of two 
types of technologies: how beams are transmitted to earth 
and the design of the satellite and receiver module [11]. The 
first technology is further divided into three categories: the 
method of collecting solar power in space, transmitting the 
power to earth, and receiving the power on earth.  

On the other hand, concerns about SPS are regulations, 
adverse health effects, terrorism, and profit. The fear of 
terrorism is a problem because of the high-power microwave 
source and the high gain antenna, which produces an extreme 
surge of energy that could be used as a weapon. The main 
worry about the SPS is that of profit since they can cost as 
much as hundreds of millions of dollars over time [5]. This, 
however, could be understood for a future of clean energy in 
an economy of growing demand. Regarding the future of the 
technology, over time more deliveries of the crew, fuel, and 
other cargo will be needed for the International Space Station 
(ISS). This information proves that there is a need for the 
development of more efficient launch technologies. By 
considering all these factors, the objective of this study is to 
determine the present possibility and future use of SPS 
systems.  

2. Solar Power Collection 

There are various proposed ideas for collecting solar 
power. Photovoltaic cells that exchange the solar energy for 
direct current (DC) electricity can be used. Even though this 
idea seems a desirable choice, silicon cells are susceptible to 
radiation. This indicates that the accumulator would have to 
be made of gallium-arsenide (GaAs) cells, which have an 
increased resistance to radiation. Although these cells are 
radiation resistant and have efficiencies over 30%, their costs 
are two orders of magnitude higher than regular silicon solar 
cells [12]. Another option within photovoltaic systems is thin-
film cells. These thin-film cells help to keep costs down, being 
that they are the cheapest type of PV cells. This arrangement 
of a system can output efficiency of 6% to 25% that produces 
an overall electric power flux production of 150 W/m2. One of 
the other concepts observed is the space electric power 
production approach of solar dynamic systems that use heat 
to run a thermal cycle connected to a generator. This method 
has a higher efficiency than the PV array/battery systems 
reaching 20-30% and can distribute continuous power in LEO 
without batteries [13]. The last possible method for solar 
collection is to use space solar energy by orbital mirrors of 
ample size, made of reflective thin film plastics, to converge 
and provide energy. Additionally, power storage may be 
required to keep a constant supply of power in the SPS. 
Smaller satellite systems use on-board storage devices such 
as lithium polymer or lithium-ion batteries with specific 
energies between 150-250 Wh/kg [14]. For the SPS case, the 
PV GaAs solar cell choice can be employed due to its reliability 
and wide literature available. Likewise, a group of Li-ion 
batteries can be used to provide the SPS with additional 

power as a redundant measure to ensure its systems are 
online at any given time.  

3. Microwave Transmission 

Since the wired transmission is extremely unfeasible due 
to the long distances, a low radio frequency in the microwave 
spectrum (2.4 GHz) or higher within the infrared range is 
needed. The most popular models for SPS rely on microwave 
transmission systems to convey the power they collect to 
earth [15–17]. Microwaves are a form of low-energy 
electromagnetic radiation that exhibit wavelengths of 1 mm 
to 30 cm and are well suited for carrying energy through 
space [15]. These systems convert DC electrical power into 
radiofrequency (RF) power, which is transmitted through 
free space and eventually converted from RF power back to 
DC electrical power [16,18]. For its implementation on SPS, 
frequencies of 2.4 GHz to 3.3 GHz (13 cm~10 cm) are 
generally selected because these wavelengths provide for 
maximum efficiencies over long distances when attenuation 
over time and losses due to atmospheric effects are 
considered [15–18]. For a plant of 5 GW total power 
transmission, the transmitting antenna would need to be on 
the scale of 1 km in diameter and the rectenna on the scale of 
7 km in diameter. These dramatic antenna sizes are needed to 
create an energy distribution at the rectenna that is non-
destructive to the environment, safe for people, and thermally 
manageable [15,16]. The connection and concentrated 
delivery of microwaves from the transmitting antenna to the 
rectenna would be coordinated and maintained via a guiding 
laser. The uplink between the satellite and the rectenna 
located on the surface of the earth could be online over 99% 
of the year due to the geometries of its orbit [15,18]. This 
entails nearly 24 hours of solar power generation. This 
technology is desirable because it offers relatively high-
efficiency conversion and energy delivery in the range of 
50%-75% DC to DC efficiency [19]. In addition to the more 
extended collection periods and efficient power delivery 
allowed by microwave transmission, the photovoltaic cells 
could maintain an ideal relationship with the position of the 
sun, further maximizing their efficiency. In terms of possible 
challenges, the likelihood of a malfunction occurring in the 
systems controlling the uplink between the antenna and 
rectenna poses a potential hazard in the form of a straying 
microwave beam. If power concentrations are above 
allowable levels, this potential malfunction could pose a 
threat to the health of humans and other organisms. For this 
and for legal reasons, power concentrations reaching the 
ground would need to be ensured below allowable levels as 
regulated by the Environmental Protection Agency (EPA) in 
the United States or the equivalent regulating body in each 
given country utilizing this technology. This raises another 
issue: the lack of international precedence for such a utility. 
An SPS system utilizing microwave power transmission in the 
gigawatt range would involve every political territory 
surrounding the equator that it passes over, necessitating 
new international guidelines and agreements to regulate and 
allow for such systems. For obvious reasons, this could prove 
to be a particularly reluctant concern. Furthermore, due to the 
power intensity of such a signal, fears about this technology 
being weaponized may arise. Transmitting a microwave beam 
in the gigawatt range of power through the air will completely 
erase any wireless communications attempting to cross its 
path and heavily distort communications even at 
considerable distances from the rectenna. This impasse is the 
primary issue limiting the broader usage and development of 
wireless power transmission historically [16]. 



G.A. Urdaneta et al. /Future Energy                                                                                           August 2022| Volume 01 | Issue 02 | Pages 09-16 

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Land usage and availability remain a problem regarding 
the microwave power transmission, as they have for other 
conventional energy production methods, due to the dramatic 
scale the rectifying antenna requires [15]. This necessity 
highlights land as the primary limiting factor involved in the 
implementation of a viable SPS utilizing microwave power 
transmission and diminishes the perceived potential for the 
scalability of such systems. Although low energy microwaves 
on a scale of up to a few millimeters are generally believed to 
not affect humans or animals, there exist no definitive studies 
which demonstrate the impact or lack thereof of prolonged 
human exposure to moderate concentrations of waves in the 
infrared spectrum. This system's unprecedented and 
dramatic nature may produce unforeseen ecological and 
human risks. 

4. Effects of radiation on solar cells and electrical 

components 

Radiation is a significant factor in orbit. To account for 
this, both spacecraft and equipment require extensive 
shielding against it, thus making them heavier, which is not 
optimal for space missions [20]. Satellite semiconductor 
materials are especially susceptible to collected radiation 
doses. In harsh space conditions, highly charged particles and 
electromagnetic rays constantly bombard electrical 
components and solar cells, causing continuous performance 
degradation. Charged particles consist of electrons with 
energies of up to 10 MeV and protons that can carry hundreds 
of megaelectron volts of energy. Cosmic rays also constitute a 
problem due to their high ionization capabilities, ability to 
carry gigaelectron volts of energy [21]. When these particles 
impact the semiconductor material, the energy carried by the 
particle is transferred to the atoms, displacing them from 
their initial positions. The shifted atoms will be incapable of 
efficiently conducting current in the electric components, 
reducing the materials’ conductivity. In the case of solar cells, 
the displacement damages caused by the shifted atoms will 
decrease the carrier’s diffusion length, subsequently 
producing diminished performance [22,23]. To efficiently 
shield electronic devices and solar units in the SPS from 
radiation, it is necessary to know how vulnerable these 
elements are, the yearly dose presented at geostationary orbit 
(GEO), and the lightest materials that will provide the 
maximum shielding. Bhat et al. [24] determined the yearly 
radiation dose at GEO using radiation-sensitive field-effect 
transistors (RADFETs). Different aluminum spherical covers 
with variable thickness were used to shield the system 
components. The results showed that for an aluminum shield 
thickness of 11 mm the yearly radiation amount was four 
orders of magnitude lower than those elements that did not 
present protection. From Figure 1, it is possible to observe 
that the optimal aluminum thickness for electric component 
shielding is located between 7 mm and 11 mm, since thinner 
walls would dramatically increase the radiation impact, and 
thicker walls would only be able to produce marginal 
decreases in the radiation effects [24]. Although it is essential 
to keep in mind that the added weight caused by the 
implementation of shielding would increase launching costs, 
therefore, thinner walls (< 7 mm) for system protection 
would be preferable. Even if a wall thickness of 11 mm is 
chosen, the amount of radiation the electric systems are 
bombarded with is still 700 times higher than on earth. 
Therefore, lighter materials that can be more effective against 
radiation are needed, such as bismuth oxide doped glasses 
[25]. Moreover, solar cells in the SPS would also be drastically 
affected by ionizing radiation, therefore, it is essential to 

understand the failure mechanisms presented in them. 
Irradiation environments cause ionization and shift damage 
(non-ionizing) failure processes in solar cell units [26]. The 
latter is the leading cause of degradation in extraterrestrial 
solar panels. Figure 2 and Figure 3 show the relative damage 
coefficient for dual GaAs/Ge junction solar cells as functions 
of proton and electron energy, respectively. 

 

Figure 1. Ionizing radiation dose as a function of 
aluminum dome thickness [24] 

Figure 2. GaAs/Ge Solar cell relative damage as a function of 
proton energy for different cover glass thickness [27] 

It is possible to observe that to maximize useful solar cell 
life, it is necessary to have at least a 6 cm cover glass plate on 
the panels. The employment of such a plate would keep 
proton damage at a minimum, but it would not be effective 
against high-energy electron impacts (over 10 MeV ). 
Contrarily, these high-energy particles are comparatively 
uncommon (below 1% of all given protons and electron 
impacts have energy over 300 keV, see Figure 4) thus, the 
employment of a 3 cm thick cover glass or thinner is also 
viable to eliminate damaging radiation [28]. Another option is 



G.A. Urdaneta et al. /Future Energy                                                                                           August 2022| Volume 01 | Issue 02 | Pages 09-16 

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the implementation of nanowire array solar cells that may 
reduce the need for shielding, particularly protons with 
energies between 100-350 keV and 1 MeV electron [20].  

Figure 3. GaAs/Ge Solar cell relative damage as a function of 
electron energy for different cover glass thickness [27] 

 

Figure 4. Probability distribution of particle occurrence in 
geosynchronous orbit as a function of their temperature 

(energy) [28] 

Since weight is such a critical factor for the SPS design, it 
is necessary to determine the estimated mass addition for a 5 
GW SPS with a solar panel surface area of 14 km2 at 368.82 
W/m2. The borosilicate type CMG cover glass is a typical 
material used to cover GaAs solar cells due to its superior 
optical, radiation, solar absorbance, and emissivity properties 
[29,30]. At a density of 2554 kg/m3, if 1 cm CMG cover glass 
thick is chosen the total shielding mass would be 3.5756 *108  
kg making the project infeasible. Therefore, the protective 
thickness must be reduced at the expense of radiation 
protection. If 100 microns of CMG shields are used, the total 
mass is significantly decreased to 3.5756 *106 kg. Figure 5 
shows the total SPS mass for different shielding thicknesses. 
This is still incredibly heavy, but it would make the SPS 
possible while simultaneously obtaining radiation protection. 
In conclusion, radiation shielding can be achieved with a 
thickness of 100 microns of CMG cover glass at the expense of 
extra cost and weight. 

Figure 5. SPS total mass for CMG cover glass thickness 
of 0.01, 0.001, and 0.0001 m 

 

5. Propulsion system  

In terms of the desired orbit, NASA stated that the best 
place for a solar space station is in GEO. By placing the system 
in GEO, it would be possible to maintain a fixed connection 
between the transmitting and receiving antenna by keeping 
the SPS fixed relative to the surface of the earth. This would 
enable the energy supply to large population zones around 
the planet [31]. For the SPS to stay in orbit, avoid collisions, 
and adjust the effects of solar pressure (which is going to 
produce substantial deviations due to the SPS’s ~14 km2   
surface area) it will need a propulsion system capable of 
quickly changing its trajectory. The fuel mass must be kept to 
a minimum to prevent increases in launch cost while 
simultaneously having enough to complete the spacecraft 
mission time. To accomplish this objective, the thrusters must 
be as efficient as possible (high specific impulse) while at the 
same time being able to provide enough thrust for quick 
reaction maneuvers. Electric thrusters are a promising option 
due to their increased efficiencies, although most are 
incapable of producing enough thrust. Even though the thrust 
produced by electrostatic acceleration systems is around two 
orders of magnitude lower than their chemical counterparts, 
they can achieve higher specific impulses. A desirable 
propulsion system for the SPS could be that of the Hall 
thruster. They can achieve specific impulse values of ~1500 
seconds, which is almost ten times higher than those from 
chemical combustion engines. It is also worth mentioning that 
Hall propulsor efficiency increases as the power supplied 
rises. Hall engines work by creating a radial magnetic field in 
their circular ionization chamber capable of accelerating 
electrons. Then a neutral gas, generally xenon, is released into 
the chamber to be ionized; this ionized gas is later expelled 
from the chamber at elevated velocities along with a stream 
of electrons to maintain the spacecraft’s electrical neutrality 
[32]. The SPS can employ Hall engines because they can 
provide enough thrust (0.01 N-0.25 N) to perform fast 
changes in the trajectory; they also have the capability of 
increasing their produced thrust from their known limits 
since no technical limitations have been found when 
supplying more than 100 kW of power [33,34]. 

6. Comparison With Terrestrial Solar Power 

Generation (TSPS) 

It is crucial to evaluate the efficiency of space solar 
stations to conventional solar power plants. The average solar 
power per unit area on the surface of the earth is 250 W/m2 
compared to ~1360 W/m2 in space near earth [35]. The 
maximum efficiency of conventional photovoltaic cells is 
around 20%, while multi-junction photovoltaic cells designed 



G.A. Urdaneta et al. /Future Energy                                                                                           August 2022| Volume 01 | Issue 02 | Pages 09-16 

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for satellites can maintain efficiencies of around 30% and 
35% [22,36]. This results in an overall power production of 
50 W/m2 on earth and 409.8 W/m2 on the SPS system. When 
considering the efficiency of microwave power transmission 
of 90% the power delivered to earth by the SPS will be 368.82 
W/m2 of PV surface [15]. However, over the course of a day, 
this loss is compensated for by the fact that solar exposure is 
continuous in the SPS, meaning that the average power 
production will be maintained at 368.82 W/m2 compared to 
the terrestrial panel, which will average only 14.6 W/m2 over 
the course of the day. This means that in terms of actual 
power generation, conversion and transmission of solar 
power is over twenty-five times as efficient on SPS systems 
when compared to terrestrial ones, with a percent difference 
of 184.8%. However, this efficiency neglects one critical 
factor, which is the land area required for the rectenna. 
Therefore, the true power generated in terms of power flux 
(W/m2) from SPS systems will be limited by the power flux 
density allowable, which is generally dictated by safety 
guidelines established by government organizations. As this 
is the case, the true efficiency in W/m2 of power generation 
using a SPS transmitting 5 GW at 3.3 GHz at 90% efficiency, in 
terms of land area needed on earth, is 100 W/m2 [15]. Even 
though this is a critical issue, the SPS is still over six times 
more efficient (in terms of surface coverage) than 
conventional PV systems.  

7. Cost analysis: current and predicted budget 

The main problem with the current SPS stance is its 
immense size: a 1 km transmitting antenna, 7 km receiving 
antenna, and ~14 km2 of solar panels are needed to produce 
the desired 5 GW of power at the power density of 368.82 
W/m2. Therefore, the SPS will be extremely heavy which 
causes a dramatic increment in the station’s initial price due 
to expensive launch costs to GEO. If an area density of 1.76 
kg/m2 (3 mm thick) for solar panels is considered, the solar 
panels would weigh an estimated 23859 metric tons. To put 
this size into perspective, the SPS panels without the 
transmitting antenna would be around 47 times heavier than 
the International Space Station (ISS). Although launch costs to 
Low Earth Orbit (LEO) have been reduced by a factor of 20 
over the past two decades, the current cheapest cost per 
kilogram to LEO has been achieved by SpaceX’s Falcon Heavy 
with a value of 1400 $/kg [37]. The cost to take a kilogram of 
payload to GEO orbit is generally six times greater than that 
of LEO. These factors result in an expense of around $200 
billion just for the launching phase of the station panels. If the 
shielding weight is factored in, that would be an additional 
$30 billion in launching costs. The manufacturing costs of 
silicon solar cells would also have to be included; considering 
a solar panel price of 100 $/m2 the total expenditure would 
amount to $5 billion. It is necessary to consider that the actual 
solar cells needed are made of Gallium-Arsenide, which is 
significantly more expensive when compared to silicon cells 
which would further drive costs up. Additionally, the 
development of both transmitting and receiving antenna 
would also have to be considered, the former further 
increasing launch costs since it is going to be located 
alongside the solar units in space. An estimate for the 
development and manufacture of both receiving and 
transmitting antennas would be around $20 billion. This 
estimation was performed by comparing the total surface 
area of both transmitting and receiving antenna with the 
FAST telescope area, then that ratio was multiplied by the 
FAST construction cost of $100 million [38]. These 
considerations would make the initial project cost $255 

billion, rendering the project presently impractical. From 
Figure 6 it is possible to observe the cost distribution for the 
SPS at the current 2022 US dollars (USD). 

Figure 6. Current SPS total cost distribution in 2022 billion 
USD 

Therefore, to make the project economically viable, 
launch costs to GEO must be decreased by a factor of 10 when 
compared to the current prices to LEO performed by the 
Falcon Heavy rocket (~140 $/kg), solar cell efficiency must be 
increased to 40%, and solar cell density should be reduced 
from 1.76 kg/m2 to 1 kg/m2 on 3 mm thick units while 
improving their radiation resistance. Making an estimation by 
including the different assumptions stated above, a cost of 
$48 billion can be obtained. Figure 7 shows the cost 
distribution after these predictions in 2022 USD. Although the 
new costs for the solar power station could be dramatically 
reduced, this final overall price is still incredibly expensive for 
just one private company to assume; therefore, international 
support and private consortiums are essential to improve the 
feasibility of the task.  

 

Figure 7. Predicted SPS total cost distribution in 2022 billion 
USD 

8. International competition and recent progress  

As previously mentioned, launch costs to LEO have been 
reduced by a factor of 20 over the past two decades, which has 
enabled space accessibility for a broader range of 
organizations. These extraordinary launch cost reductions 
along with continuous breakthroughs in Photovoltaic 
technology, WPT, and radiation shielding methods, have 
reignited the interest of international organizations, private 
companies, and governments in space solar energy [39]. In 
the US, through sponsored research by Northrop Grumman, a 
group of scientists at the California Institute of Technology 
asserts to have developed an SPS model capable of emitting 
solar energy from space [40]. The US government has also 
shown some interest in the idea over the years; in 2007 the 
National Security Space Office (NSSO), through its report 
“Space-Based Solar Power as an Opportunity for Strategic 



G.A. Urdaneta et al. /Future Energy                                                                                           August 2022| Volume 01 | Issue 02 | Pages 09-16 

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Security” concluded that this technology could advance the 
United States’ geopolitical stance in the contemporary space 
race [41]. In this regard, the US military leads the most 
important effort in the country by allocating $178 million 
towards solar space power research and development [40]. In 
this new space race, private companies are now capable of 
contributing towards space solar technology. Firms such as 
Solaren, PowerSat Corporation, and Space Energy are tackling 
different challenges under this project. Companies are 
unifying efforts to achieve this, as it is the case with Solaren 
who partnered with Pacific Gas & Electric to deliver power 
from space. On the other hand, PowerSat Corporation has 
focused on the technological challenges of the project. This 
eager participation from the private sector shows how this 
technology has a promising future in relation to humanity’s 
net-zero emissions goal [41]. The European Space Agency 
(ESA) is also interested in this technology. The agency has 
started an initiative to demonstrate the SPS potential for 
providing energy by selecting 13 ideas for funding. Since solar 
power from space is an interdisciplinary problem, these 
research topics deal with distinct challenges such as sunlight 
collection or wireless transmission safety [42].  In 2021, the 
ESA hosted a workshop about solar power satellites with the 
goal of investigating the SPS impact on fighting climate 
change. In addition, the space agency also performed a cost 
analysis to determine the feasibility of the SPS business as a 
source of clean energy [42]. China is also trying to obtain an 
advantage in this possible new market. The country is 
preparing to launch a demonstrative SPS around the 2030 
and a commercial station by 2050 [39]. To achieve this 
deadline, the Chinese state has funded the Bishan project, 
which is focused on creating a floating platform that will rise 
300 meters above the ground and attempt to transfer the 
solar energy captured to the surface. If successful it will be 
relocated at 22 km above earth surface to continue testing 
[43]. They also expect to complete their high voltage 
transmission line and wireless energy transfer tests by the 
end of the decade, which will allow the rapid scaling of WPT 
technology for the SPS [40]. Another country that has also 
started to commercialize solar space technology by 2050 is 
Japan. In 2017, the Japan Aerospace Exploration Agency 
(JAXA) announced that it would have an SPS online by the first 
half of this century. The Japanese agency has partnered with 
Mitsubishi to develop a demonstration system capable of 
supplying megawatts of energy and has redirected many of its 
resources into WPT and robotic assembly technology 
research [44,45]. Considering these aspects, SPS technology 
has the potential to change the world. In 2021, the energy 
consumed in the US was about 4 trillion kilowatt-hours [46]. 
If only one 5-GW solar power station is considered, it would 
be able to provide 1% of all the energy US citizens consume in 
a year, assuming it would be online on a daily basis. It is also 
important to note that this power would not be constrained 
by weather patterns, as it is the case for solar and wind, and 
price fluctuations due to geopolitical conflicts, unlike oil and 
natural gas. However, and most importantly, this technology 
gives humanity the chance to achieve a future with zero net 
emissions. Therefore, it is possible to conclude that more 
international cooperation is needed to accomplish this goal.  

9. Conclusion 

The feasibility of solar satellite space stations was 
explored through the lenses of current technology. Present 
innovations were proposed for the development of the 
system while simultaneously discussing the challenges it 
would face. It was determined that the most beneficial orbit 

to locate the system was at GEO because it would allow the 
station to be on a fixed-point relative to earth. Gallium-
Arsenide PV cells can be a viable option for power collection 
due to their high efficiencies and radiation resistance 
properties. Regarding the power transmission from the 
station to the receiving antenna, the desired frequencies are 
from 2.4 GHz to 6 GHz, being these the magnitudes that 
present the least atmospheric attenuation and thus being the 
most efficient to transmit power. Using these frequencies, a 
total of 5 GW of power can be achieved at 90% efficiency. 
When it comes to ionizing radiation, a CMG cover of 100 
microns can be used to reduce solar cell damage. Moreover, it 
was determined that Hall thrusters would be the optimal 
propulsion system for the station since they can provide the 
most advantageous combination between fuel efficiency and 
thrust. In terms of present viability, it was determined that 
the SPS is not economically possible mainly because of launch 
mission costs to GEO. Technical challenges such as reduction 
of solar unit density, increase in cell efficiency, and radiation 
shielding are some of the most important factors to make the 
SPS a viable option. In addition, a project of this magnitude 
would require the cooperation of several entities to make it a 
reality requiring international and private support. In 
conclusion, more research must be done regarding the 
reduction of payload costs to LEO and the development of 
radiation-resistant and efficient solar units to provide a future 
where satellite power energy is possible. 

Ethical issue 
The authors are aware of and comply with best practices 

in publication ethics, specifically with regard to authorship 
(avoidance of guest authorship), dual submission, 
manipulation of figures, competing interests, and compliance 
with policies on research ethics. The author adheres to 
publication requirements that the submitted work is original 
and has not been published elsewhere in any language. 

Data availability statement 
Data sharing is not applicable to this article as no datasets 

were generated or analyzed during the current study. 

Conflict of interest 

The authors declare no potential conflict of interest. 

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