Milestone-Proposal:First Solar Battery-operated Installation in Japan
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Docket #:2025-13
This is a draft proposal, that has not yet been submitted. To submit this proposal, click on the edit button in toolbar above, indicated by an icon displaying a pencil on paper. At the bottom of the form, check the box that says "Submit this proposal to the IEEE History Committee for review. Only check this when the proposal is finished" and save the page.
To the proposer’s knowledge, is this achievement subject to litigation? No
Is the achievement you are proposing more than 25 years old? Yes
Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes
Did the achievement provide a meaningful benefit for humanity? Yes
Was it of at least regional importance? Yes
Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes
Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? Yes
Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes
Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes
Year or range of years in which the achievement occurred:
1958
Title of the proposed milestone:
First Solar battery-operated installation in Japan, 1958
Plaque citation summarizing the achievement and its significance; if personal name(s) are included, such name(s) must follow the achievement itself in the citation wording: Text absolutely limited by plaque dimensions to 70 words; 60 is preferable for aesthetic reasons.
Japan’s first solar panel was installed at Mount Shinobuyama radio relay station by Tohoku Electric Power and NEC. in 1958, starting to generate 70 watts to power a 45-watt relay module for 24/7 operation. This pioneering off-grid system demonstrated solar energy’s viability, sparking advancements in photovoltaic and rechargeable battery research, and contributing significantly to Japan’s ongoing efforts in sustainable energy innovation.
200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.
In 1958, Japan achieved a pioneering milestone in renewable energy with the implementation of a solar-powered radio relay station by Tohoku Electric Power Co., Inc. and NEC. Located on Mount Shinobuyama, this off-grid facility utilized 4,320 silicon solar cells and nickel-cadmium batteries to generate 70 watts, reliably operating a 45-watt transistor-based relay module continuously.
The station's success marked the first real-world application of solar power in Japan for critical infrastructure. At a time when photovoltaic technology was largely experimental, this achievement demonstrated solar energy's practical viability in remote and harsh environments. It also showcased the effective integration of generation, storage, and low-power electronics—a blueprint for modern renewable systems.
This system influenced Japan’s technological trajectory in solar and battery research. It attracted attention from academia and industry, inspiring future installations in isolated locations such as mountains, islands, and post-disaster zones.
In addition to its technical contributions, the project had profound social implications. It enhanced the safety and efficiency of operations in remote communication networks while reducing reliance on fossil fuels and minimizing maintenance.
The Shinobuyama system is widely recognized as a cornerstone in Japan’s journey toward sustainable energy. Its legacy continues to resonate through current renewable energy policies and innovations. As one of the earliest reliable, autonomous solar installations worldwide, it represents a historically significant and forward-looking accomplishment in electrical engineering.
IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.
IEEE Power and Energy Society
IEEE Electron Devices Society
In what IEEE section(s) does it reside?
IEEE Sendai Section
IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:
IEEE Organizational Unit(s) paying for milestone plaque(s):
Unit: IEEE Sendai Section
Senior Officer Name: Hiroaki Muraoka
IEEE Organizational Unit(s) arranging the dedication ceremony:
Unit: IEEE Sendai section
Senior Officer Name: Hiroaki Muraoka
IEEE section(s) monitoring the plaque(s):
IEEE Section: IEEE Sendai Section
IEEE Section Chair name: Hiroaki Muraoka
Milestone proposer(s):
Proposer name: Chiaki Ishikawa
Proposer email: Proposer's email masked to public
Proposer name: Katsumasa Mukaiyama
Proposer email: Proposer's email masked to public
Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.
Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):
Green Plaza, Tohoku Electric Power Company (3-7-1, Ichiban-cho, Aoba-ku, Sendai, Miyagi, 980-0811 Japan)
GPS Coordinate: 38.2617286,140.8708429,17
Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.
Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The plaque will be placed on showroom named Green Plaza of Tohoku Electric Power at Electric Power Building.
Are the original buildings extant?
No.
Details of the plaque mounting:
The plaque will be displayed in the Green Plaza of Tohoku Electric Power at Electric Power Building.
How is the site protected/secured, and in what ways is it accessible to the public?
Visitors can come to the Green Plaza of Tohoku Electric Power without security check.
Who is the present owner of the site(s)?
Tohoku Electric Power Co., Inc.
What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include detailed support at the end of this section preceded by "Justification for Inclusion of Name(s)". (see section 6 of Milestone Guidelines)
Historical Significance
The Shinobuyama Relay Station
Overview of the Radio Relay Station Using Solar Cells
In 1957, only three years after solar cells were first developed at Bell Labs in 1954, Tohoku Electric Power Company decided to use solar cells as the power source for a radio relay station located in a remote area. This station was intended to facilitate communication for service vehicles patrolling the power distribution network in rural regions by relaying signals through a central radio relay station set up in these areas. Because the site was so remote, it was not possible to supply electricity from a regular power grid, making solar cells a viable option for securing power.
Mr. Hayashi and his team from NEC participated in this project. The goal was to install the relay station on top of Mount Shinobuyama (elevation: 268 meters) in Fukushima Prefecture. The communication system used very high frequency (VHF) radio waves, and to reduce power consumption, some components used transistors, resulting in a total power requirement of approximately 45 watts. To address the lack of sunlight during nighttime, rechargeable batteries were considered. Sealed nickel-cadmium batteries were chosen for their durability against overcharging, high charging efficiency, and long lifespan.
The Shinobuyama Relay Station stands as a rare example of a project that was technologically audacious, socially beneficial, and strategically farsighted, at a time when few institutions worldwide were thinking along those lines. It not only pioneered the use of solar technology on Earth but also helped shape the direction of Japan’s energy innovation and policy for decades to come.
Installation of 4,320 Solar Cells on Mount Shinobuyama
In August 1958, a total of 4,320 solar cells, each 28 mm in diameter, were manufactured at NEC’s research facility, assembled into modules, and produced a total output of 70 watts. This output was about five times the relay station’s average power consumption. In early November 1958, solar panels were installed on the roof of the Shinobuyama wireless relay station, as shown in Figure 1. The panels were oriented due south and tilted at an angle of 40° ±7°. This relay station, Japan’s first to use solar cells, officially began operation on November 15, 1958 [5], [6].
This relay station used two 150 MHz transceivers, with a total power consumption of 4.5 W, all supplied by silicon solar cells. To prepare for nighttime or bad weather, the solar cell output is float-charged into Ni-Cd storage batteries. The battery capacity is sufficient to keep the equipment operating even during about a month of continuous poor weather.
The solar cell system was designed with a substantial safety margin, with a maximum output of approximately 70 W. The array consists of 4,320 solar cell elements, each about 28 mm in diameter, grouped into blocks of nine and molded in acrylic resin. These are mounted on a 2 m × 2.5 m iron flat frame, which is installed on the roof of the station building. As shown in Fig. 1, the frame is oriented due south and tilted at an angle of 40° ±7°, to maximize solar energy absorption throughout the year.
Figure 1 The Shinobuyama Wireless Relay Station
The Completion Date of Tohoku Electric Power’s Solar Battery-operated installation
The completion date of the solar power generation facility operated by Tohoku Electric Power was verified through documents provided by three different affiliated companies.
Based on References [6] it was confirmed that the facility commenced operation on November 5, 1958.
Reference [4] and [5] indicates that the facility became fully operational as a radio relay station on November 15, 1958.
Conclusion
The 1958 installation on Mount Shinobuyama was Japan’s earliest real-world implementation of solar power for telecommunications infrastructure. At a time when photovoltaic technology was still emerging globally, Japan demonstrated an advanced integration of solar cells, battery storage, and low-power electronics in a critical application. This project preceded broader global adoption of off-grid solar power systems and stands as a testament to Japan’s early leadership in practical renewable energy deployment.
Technological Impact
The Shinobuyama installation was not merely symbolic; it represented a carefully engineered and highly reliable system at a time when solar power was largely experimental. Its technical success proved that solar energy could sustain critical communications infrastructure year-round, even in remote areas with harsh weather conditions. The project showcased the synergy between energy generation, storage, and power-efficient electronics—setting a template for modern off-grid solar systems.
At the time, solar photovoltaic technology was still considered experimental. Solar cells had low energy conversion efficiencies (around 6–10%), high production costs, and little to no proven reliability in real-world terrestrial environments. Despite these limitations, this project adopted solar power not as a supplementary or backup source, but as the primary and sole energy supply for a critical communication facility located on a remote mountaintop where no commercial power lines were available.
The system was remarkable not only for its ambition but also for its technical execution. It featured an integrated energy management design combining solar panels with rechargeable batteries, enabling 24-hour operation regardless of weather conditions or seasonal variations in solar insolation. NEC (Nippon Electric Company, now NEC Corporation) developed and manufactured the solar cells domestically, making this one of the earliest examples of Japan’s indigenous capacity in solar technology development.
The success of this installation provided early empirical data on the performance, durability, and maintenance requirements of solar cells in harsh weather conditions—data that was invaluable for future technological improvements. It also spurred innovation in designing low-power, resilient communication equipment, influencing later generations of off-grid and energy-autonomous systems.
Social Impact
Beyond its technical merits, the Shinobuyama wireless relay station project demonstrated the social value of renewable energy. It improved safety for maintenance crews, reduced dependence on fuel delivery to remote areas, and became an inspiration for energy solutions in isolated communities. Its success encouraged policymakers and engineers to explore renewable options for rural electrification and disaster resilience.
From a societal perspective, the Shinobuyama station helped bridge the communication gap between remote mountainous regions and urban centers, significantly enhancing public safety, disaster response, and information accessibility. At a time when rural and isolated areas in Japan were still underserved by modern communication infrastructure, the deployment demonstrated how renewable energy could serve as an equalizer, bringing essential services to difficult-to-reach communities.
This initiative also raised public awareness of alternative energy possibilities at a time when Japan was rapidly industrializing and increasingly dependent on imported fossil fuels. It became an early symbol of energy independence and environmental consideration, both of which would become major themes in Japanese society in the decades that followed.
Policy and Strategic Impact
Strategically, the Shinobuyama project influenced Japan’s national trajectory in renewable energy policy. The successful demonstration of solar energy’s practical utility led to increased government and industrial support for PV research and development in the 1960s and beyond. The project helped justify early investments into solar energy by showing its viability outside laboratory settings, paving the way for long-term institutional interest.
In the broader international context, this installation predates many of the widely recognized policy shifts toward renewable energy. It can be seen as a precursor to the global movement toward sustainability and carbon reduction, decades before the 1970s oil crises that drove many countries to re-evaluate their energy strategies.
What obstacles (technical, political, geographic) needed to be overcome?
Challenges and Solutions
In the 1950s, implementing a solar-powered communication relay station posed significant challenges across technological, political, and geographical domains.
Technical Challenges
Solar cell efficiency was low (around 6–10%) and output was limited.
Battery storage technology, particularly lead-acid batteries, had limitations in lifespan and performance in cold environments.
Equipment needed to operate continuously with minimal maintenance under variable weather conditions.
Solutions:
The communication equipment was specially designed to be low-power and reliable.
Solar panels were installed at optimized angles and orientations to maximize power generation.
A robust system was developed combining solar panels and storage batteries, ensuring stable operation even during cloudy weather and at night.
Weatherproof enclosures and durable materials were used to withstand snow, wind, and temperature variations.
Political Challenges
In the post-war reconstruction period, Japan’s national energy policy focused on thermal and hydroelectric power, with little to no support for renewable energy technologies.
Solar power was not yet socially or institutionally recognized as a viable energy source, making institutional backing difficult.
Solutions:
Tohoku Electric Power collaborated with the NEC to independently research and implement the system, bypassing national policy limitations.
By demonstrating the system’s reliability in a real-world setting, they helped establish public and technical credibility for solar power.
Geographical Challenges
The mountaintop site (Shinobuyama) was difficult to access and exposed to severe weather.
Commercial power lines were impractical to install due to terrain and cost.
Fuel-powered generators were unsuitable due to the logistical challenges of fuel transport and maintenance.
Solutions:
A fully autonomous power system using only solar energy and batteries was implemented.
Remote monitoring and infrequent maintenance were made possible through robust system design.
The solution provided a model for similar installations in remote or difficult environments.
What features set this work apart from similar achievements?
Comparison with Other Power Supply Methods and Global Context (Including US Research)
In the 1950s, when the Shinobuyama Wireless Relay Station was constructed, solar photovoltaic technology was still in its infancy. While photovoltaic (PV) cells had been demonstrated in space applications, their use in terrestrial, practical systems was not widespread. Globally, several institutions were exploring solar power for various applications, and key research in the United States, particularly at Bell Labs, was instrumental in the advancement of PV technology.
U.S. Research and Bell Labs
In the United States, Bell Labs made significant strides in the development of solar cells. The first practical silicon solar cell, developed in 1954 by Dr. Gerald Pearson, Dr. Calvin Fuller, and Dr. Daryl Chapin at Bell Labs, marked a breakthrough. This solar cell had an efficiency of about 6%, a significant improvement over previous prototypes. While this was a major technological advancement, the application of these cells was still primarily experimental or confined to specialized uses, such as space exploration. The use of solar cells for power generation in terrestrial, non-experimental settings, like communication systems, was not yet common.
Solar Power Adoption in Space Applications
By 1958, the Vanguard I satellite famously became the first man-made object to be powered by solar cells in space. This marked the first practical application of solar power, though it was in an extraterrestrial context rather than for ground-based infrastructure. Space missions such as these showcased the potential of solar power but did not provide solutions for earthly, terrestrial needs like powering remote communications systems.
Comparison with Other Power Supply Methods in the 1950s
At the time of Shinobuyama’s development, several power sources were still being considered for remote telecommunications.
Commercial Grid Power
Extending grid electricity to a remote, mountaintop location would have been prohibitively expensive and impractical due to the geographic and economic constraints. Power lines would need to be laid across difficult terrain, and the financial burden of such an installation would have made it a non-viable solution.
Diesel or Gasoline Generators
Compared to conventional diesel generators, which required regular refueling and frequent maintenance, the solar-powered solution offered silent, clean, and maintenance-free operation. This made it highly advantageous for isolated mountain sites where fuel logistics posed significant risks and costs.
Oil-based power generation were a common solution for remote locations but came with several issues. They required frequent fuel deliveries, which were difficult to manage in a remote area. They also produced noise and emissions, making them unsuitable for the environmentally sensitive mountain region where the Shinobuyama station was located.
Battery-Only Systems
While feasible in certain settings, standalone battery systems had significant drawbacks. They would require frequent recharging or replacement, which was impractical in a remote location like Shinobuyama, especially when considering the technological limits of battery storage at the time.
Solar Power as a Revolutionary Solution
The solar photovoltaic system adopted at the Shinobuyama Wireless Relay Station stood out as the only truly autonomous and sustainable solution for the location. Its adoption was a pioneering decision, demonstrating that solar cells, despite their low efficiency and high cost, could provide reliable, continuous power in a real-world, ground-based setting. The system was specifically designed to be low-maintenance, with solar panels charging Nickel-Cadmium batteries that ensured continuous operation, even during the night or cloudy days.
Unlike in the U.S., where solar was mostly limited to experimental or space applications, the Shinobuyama station proactively demonstrated the viability of solar power for continuous communication infrastructure—something that had not yet been realized in many other countries, including the U.S. This achievement made the station not only a technical pioneer but also a significant social and logistical breakthrough, as it allowed the station to provide reliable communication services in a region previously underserved by traditional power grid infrastructure.
Conclusion
Compared to contemporary methods, such as engine generators or grid power, the solar-powered solution used at the Shinobuyama Wireless Relay Station was far more suited to the remote location and long-term operational needs. It also marked an early milestone in the practical application of solar power, paving the way for future developments in renewable energy technologies that would later shape global energy practices.
In summary, while other nations, especially the U.S., were experimenting with solar power, Shinobuyama wireless relay station was among the first to integrate solar technology into a fully operational system for critical infrastructure, demonstrating the scalability and potential of solar energy for telecommunications and other off-grid applications.
Why was the achievement successful and impactful?
Why was the achievement successful and impactful?
The successful implementation of the Shinobuyama Wireless Relay Station in 1958 represents a landmark achievement in the early practical application of solar photovoltaic technology. This project not only overcame significant technical and logistical barriers but also demonstrated the transformative potential of renewable energy in critical infrastructure, well ahead of its time.
Technical Innovation and Practical Success
At a time when solar cell technology was still nascent, expensive, and largely confined to space or laboratory applications, the Shinobuyama project demonstrated the feasibility of using solar power in a terrestrial, mission-critical setting. The photovoltaic system served as the primary and sole power source for the wireless relay station, operating continuously and reliably on a remote mountaintop in Fukushima Prefecture, Japan.
The technical success of the project lay in its careful system design
The solar panels were strategically oriented to maximize solar gain, despite the region’s variable weather conditions.
Communication equipment was custom-designed to be energy-efficient, minimizing the required power budget.
A robust energy storage system using Nickel-Cadmium batteries ensured operation during cloudy periods and at night.
All components were housed in weather-resistant enclosures to withstand harsh environmental conditions, including snow, heavy rain, and strong winds.
The system’s autonomous operation significantly reduced the need for on-site maintenance—a crucial factor given the inaccessibility of the location. This operational stability validated the use of solar power in real-world conditions, setting a precedent for future off-grid power systems.
Strategic and Social Impact
The Shinobuyama wireless relay station addressed a vital societal need: the extension of communication infrastructure into underserved, mountainous regions. During Japan’s post-war reconstruction and economic expansion, reliable communications were essential for regional development, emergency coordination, and the integration of remote communities into the national information network.
By choosing solar power, the designers overcame the limitations of other power supply options:
Commercial grid power was not available in the area and would have been prohibitively expensive to extend.
Diesel generators, though technically viable, were impractical due to the logistical challenges of transporting fuel and conducting frequent maintenance in a remote area.
Solar power, on the other hand, provided a clean, quiet, and maintenance-light solution that supported continuous operation in an environmentally and economically sustainable manner. This was a radical departure from conventional engineering assumptions of the time, demonstrating that renewable energy could serve not only experimental purposes but also real and critical infrastructure needs.
Institutional Collaboration and Vision
The project was made possible through a visionary collaboration between Tohoku Electric Power Company and NEC, which combined academic research with practical field engineering. At a time when national energy policies focused on thermal and hydroelectric power, and when solar technology lacked institutional support, this initiative was undertaken independently —driven by technological curiosity and a practical problem-solving ethos.
This pioneering spirit was instrumental in building early credibility for solar power. By proving that it could reliably power important systems over extended periods, the project helped reshape public and technical perceptions of renewable energy.
Long-Term Influence and Legacy
The impact of the Shinobuyama wireless relay station extended far beyond its immediate operational role. It served as a proof of concept for the use of solar power in remote telecommunications, disaster-resilient systems, and off-grid infrastructure—domains where it is now widely accepted and applied.
Decades later, the principles validated by this project would be echoed in:
- Solar-powered base stations for mobile networks in rural areas
- mergency communications systems in disaster-prone regions
Renewable microgrids for off-grid communities
Moreover, the project contributed to the early discourse around sustainable energy use, predating major global initiatives in renewable energy by decades. It stands as a rare example of mid-20th-century renewable energy foresight, anticipating modern concerns about energy decentralization, environmental resilience, and sustainable development.
Conclusion
The Shinobuyama Wireless Relay Station was successful not just because it worked, but because it redefined what was considered possible with emerging solar technology. It had immediate utility, long-term influence, and demonstrated that renewable energy could be reliable, practical, and impactful—even at a time when the world was not yet ready to believe it.
This achievement deserves recognition as a seminal milestone in the history of both telecommunications and renewable energy.
Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.
Bibliography
The supporting materials include original photographs of the Shinobuyama installation, engineering design documents, and a technical report published by Tohoku Electric Power Co., Inc. contemporaneous with the project. These materials provide direct evidence of the system’s specifications, installation process, and long-term performance. Additional references include articles published in domestic technical journals and coverage in Japanese national newspapers, confirming both technical significance and societal attention at the time.
[1] Kazuo Hayashi; " Characteristics and Applications of Silicon Solar Cells ", Vol. 41, No. 8, pp. 780-786, IEICE Transaction, 1959. (in Japanese)
[Remarks: Translation from Japanese to English: Abstract]
Abstract
This paper describes the structure of silicon solar cells. Next, it determines the diffusion rate of boron into N-type silicon during the formation of the P-N junction by the diffusion method. Furthermore, in order to improve the conversion efficiency, it examines the causes of losses such as light reflection on the surface and internal resistance.
Additionally, the paper investigates the behavior when using the output of a solar cell for float charging of a Ni-Cd alkaline battery. It also describes the application of solar cell to a pyranometer.
[2] Kazuo Hayashi, " Solar Battery ", Vol. 43, No. 11, pp. 492-495, Journal of Illuminating Engineering Institute of Japan, 1959. (in Japanese)
[Remarks: Translation Japanese to English: Section 5.1 and 5.2]
5.1 Progress in the Application of Silicon Solar Cells: Overseas Applications
Silicon solar cells were first announced by Bell Labs in 1954. At that time, their conversion efficiency was close to 6%. Subsequent improvements in their characteristics increased the efficiency to 11%.
The first practical application took place on October 4, 1955, in Americus, Georgia, where Bell Labs used them as a power source for a rural carrier telephone system. This system housed nine solar cells per block inside plastic cases, with a total of 48 blocks—432 solar cells—mounted on the top of a utility pole. The output was 9 watts, which provided a floating charge to a 22V nickel-cadmium alkaline battery. Various experimental data were collected to assess the feasibility of using solar cells as power sources for communication systems in the future. At the time, the conclusion was that the cost was still too high to be economically viable.
5.2 Applications in Japan
Research in Japan began one year later than in the United States. As a practical implementation, at the end of last year, a solar-powered VHF unmanned relay station was installed at the summit of Mount Shinobuyama in Fukushima Prefecture as part of a joint research project between Tohoku Electric Power Co., Inc. and NEC Corporation.
All of the power required for the relay equipment is supplied by solar cells (Figure 10 of the original paper), and the output is stored in Ni-Cd batteries to ensure continued operation during nighttime or bad weather. The solar cell modules consist of 4,320 cells, each approximately 28 mm in diameter, molded in blocks of nine within acrylic resin. These blocks are connected in a suitable series-parallel configuration to achieve a total maximum output of approximately 70W. The solar panels are installed on the roof of the relay station building, facing due south at an angle of 40° ±7°. Since its installation, the relay station has operated without any issues for about a year.
In addition, solar cells are being used as a power source for lighting, such as a beacon on the Seto Inland Sea constructed by the Japan Coast Guard. The beacon’s light flashes using power generated by the solar cells. This system uses 648 cells and has an output of approximately 14W, and it is scheduled for completion by the end of October this year.
There are also a wide range of applications for solar cells as light detectors. For example, solar cells are used in sunlight detection devices that blink signal lights according to outdoor brightness levels. Various other applications as light detectors are currently under development.
Because the short-circuit current of solar cells is proportional to the intensity of the incoming light, it is possible to measure solar radiation by monitoring the photocurrent. Figure 11 shows observational data from the solar eclipse that occurred on April 19 of last year. The data reveals a remarkable correlation between the short-circuit current and the degree of solar obscuration, demonstrating the potential of silicon solar cells for use in solar radiation meters.
[3] Kazuo Hayashi, " Recent Research Perspectives: Silicon Solar Cells ", vol. 43, pp. 2-5, Optical News, 1959. (in Japanese)
[Remarks:Translation Japanese to English: pp. 2-5]
(Starting at the second last paragraph of left column of page 4)
As an example of using solar cells for power supply, both the United States and the Soviet Union have equipped artificial satellites with them. While details about the Soviet systems remain unclear, the U.S. “Vanguard satellite” is equipped with six blocks of solar cells mounted around a 6.4-inch diameter sphere. For use in satellites, solar cells with particularly high conversion efficiency —over 10% are selected. Eighteen rectangular pieces form one block, and each block is housed within a single panel window.
As shown in Fig. 8, these six blocks of silicon solar cells are connected in parallel, each via a silicon diode to prevent reverse current. The reverse-current protection diodes prevent electricity from flowing backward from the storage battery or from the sunlit cells to those shaded from sunlight.
Possible causes of solar cell damage when mounted on satellites include meteorite impacts, space dust, extreme temperatures, and X-ray and gamma-ray radiation. However, based on current data, unless there is mechanical damage, solar cells are believed to be durable enough to operate safely for several years under radiation exposure.
In other countries, solar cells are also used as power sources for unmanned lighthouses, transistor radios, and relay stations in forest observation facilities.
In Japan, in November of last year, NEC Corporation and Tohoku Electric Power Company installed an unmanned relay station powered by solar cells at the summit of Mount Shinobuyama in Fukushima Prefecture.
This relay station uses two 150 MHz transceivers, with a total power consumption of 4.5 W, all supplied by silicon solar cells. To prepare for nighttime or bad weather, the solar cell output is float-charged into Ni-Cd storage batteries. The battery capacity is sufficient to keep the equipment operating even during about a month of continuous poor weather.
The solar cell system is designed with a substantial safety margin, with a maximum output of approximately 70 W. The array consists of 4,320 solar cell elements, each about 28 mm in diameter, grouped into blocks of nine and molded in acrylic resin. These are mounted on a 2 m × 2.5 m iron flat frame, which is installed on the roof of the station building. As shown in Fig. 9 (of the original article. See Fig 1 of the application for similar photo), the frame is oriented due south and tilted at an angle of 40° ±7°, to maximize solar energy absorption throughout the year.
[4] Yukinori Kuwano: "How were solar cells invented and developed?", Ohm, pp. 49-50, 2011. (in Japanese)
ISBN: 978-4-274-50348-1
[Proposer remarks] We can see "This relay station, Japan’s first to use solar cells, officially began operation on November 15, 1958."
[Remarks:Translation Japanese to English: pp. 49-50 ]
The First Application of Solar Cells in Japan: Development of a Power Supply for the Shinobuyama Relay Station
① Overview of the Radio Relay Station Using Solar Cells:
In 1957, only three years after solar cells were first developed at Bell Labs in 1954, Tohoku Electric Power Company decided to use solar cells as the power source for a radio relay station located in a remote area. This station was intended to facilitate communication for service vehicles patrolling the power distribution network in rural regions by relaying signals through a central radio relay station set up in these areas. Because the site was so remote, it was not possible to supply electricity from a power grid of regular power company, making solar cells a viable option for securing power.
Mr. Hayashi and his team from NEC participated in this project. The goal was to install the relay station on top of Mount Shinobuyama (elevation: 268 meters) in Fukushima Prefecture. The communication system used very high frequency (VHF) radio waves, and to reduce power consumption, some components used transistors, resulting in a total power requirement of approximately 45 watts. To address the lack of sunlight during nighttime, rechargeable batteries were considered. Sealed nickel-cadmium batteries were chosen for their durability against overcharging, high charging efficiency, and long lifespan.
② The First Design of Solar Cells for Communication Use:
Through preliminary testing, the team confirmed that solar cells with a maximum output 10 times greater than the system’s power consumption could keep the system running continuously. However, since this was the first practical implementation, they developed solar cell modules with a maximum output 15 times greater than the required power to ensure reliability. Durability tests for the solar cells were conducted using a weather meter at what is recorded as the Ministry of International Trade and Industry's Craft Testing Laboratory (though it may have actually been the Industrial Testing Laboratory under the same ministry). According to the results, only a slight reduction in the transparency of the acrylic cover was observed, and no other significant issues were reported.
③ Installation of 4,320 Solar Cells on Mount Shinobuyama Around 50 Years Ago:
In August 1958, a total of 4,320 solar cells, each 2.8 cm in diameter, were manufactured at NEC’s research facility, assembled into modules, and produced a total output of 70 watts. This output was about 15 times the relay station’s actual power consumption. In early November 1958, the solar panels were installed on the roof of the Shinobuyama radio relay station, as shown in Figure 2-8 (of the original paper. See Figure 1 of this application). The panels were oriented due south with a tilt angle of 40 degrees plus or minus 7 degrees. This relay station, Japan’s first to use solar cells, officially began operation on November 15, 1958 (approximately fifty years ago from today).
[5] "30-Year History of Tohoku Electric Power (1951–1981)" (in Japanese)
[Remarks] This is a document summarizing the official history of all departments of Tohoku Electric Power.
[proposers' remarks]
We can see "After this long process, on November 15, 1958, our company introduced solar power for the first time in Japan as a power source for a VHF relay base station on Mount Shinobuyama in Fukushima City. "
Media:Tohoku_Company History.pdf
[Remarks: Translation Japanese to English ]
Japan’s First Practical Use of Solar Power:
In November 1958, Japan’s first “unmanned radio relay station powered by solar cells” was operated as an experimental station. It served as a VHF relay base station for power distribution maintenance at the Fukushima Sales Office at the time. Back then, the telecommunications division belonged to the power supply department. For about five years, data was collected, and practical field tests were conducted as a research project of the power supply division.
The solar cells had a capacity of approximately 65 watts and were used to charge nickel-cadmium (Ni-Cd) batteries during the day, which in turn supplied power during the night.
Solar Cell Radio Relay Station:
A radio relay station powered by what we call “our very first solar cell” was launched by our company in January of last year, and it has been operating successfully ever since.
(Quoted from the company newsletter, “BRIDGE”)
The World’s First Solar Cell Development:
In 1954, solar cells for solar power generation were developed for the first time in the world at Bell Telephone Laboratories in the United States. An interesting anecdote is that the silicon solar cell developed at that time (with an energy conversion efficiency of about 6%) was actually discovered by accident during transistor research — essentially a byproduct of that work.
The Road to Practical Use of Solar Cells:
However, at the time, solar cells were extremely expensive. As such, they were not something that could be used in ordinary households like today, and their use was limited to specialized applications. In March 1957, our company proposed a plan to use solar cells at the robot radio relay station on Mount Shinobuyama in Fukushima City. Following that, a basic study on solar power generation using solar cells was conducted over the course of about a year.
At the same time, in June 1957, our company submitted a “Research Agreement on Solar Cell Devices and Associated Radio Equipment” along with proposed specifications to NEC (Nippon Electric Company).
This marked the beginning of solar power research within Japan. Subsequent experiments were conducted repeatedly at NEC, and by January 1958, production facilities related to silicon semiconductors had been established at NEC’s research laboratories, initiating the manufacturing of solar cells.
The Birth of Japan’s First Solar Power System:
After this long process, on November 15, 1958, our company introduced solar power for the first time in Japan as a power source for a VHF relay base station on Mount Shinobuyama in Fukushima City. This solar power system, which started operation in the Tohoku region, consisted of an approximately 50-watt silicon solar cell combined with nickel-cadmium (Ni-Cd) storage batteries.
Due to the high peaks of Mount Shinobuyama and Mount Haguroyama within the city, VHF radio waves were obstructed, which disrupted operations. To ensure stable communication, a radio relay station was established at the summit of Mount Shinobuyama, and solar cells were used to power this relay site.
Each solar cell used in the system cost 1,000 yen at the time. With a total of 4,320 cells used, the construction of this solar power system was a major project requiring an enormous investment of management resources for that era.
Today, due to advancements in communication technology, the solar-powered radio relay station on Mount Shinobuyama is no more. However, the passion and dedication of the employees who pioneered its implementation continue to live on at the summit of Mount Shinobuyama.
In a figure, the 9 cell group board is next to a cigarette to show its size.
[6] "Tohoku Electric Power – History of the Telecommunications Department (Published April 1972)", (in Japanese)
[Remarks] This is a document specifically focused on the history of the Information and Telecommunications Department of Tohoku Electric Power.
[Proposers’ remarks] From the line of the Reference text written in Japanese marked with a yellow marker, we can see "This relay station, Japan’s first to use solar cells, officially began operation on November 5, 1958."
Media:Tohoku_Company_Communication.pdf
[7] "Tohoku Electric Power – In-house Historical Record", (in Japanese)
[Remarks]
This is a document compiled primarily by former employees (OBs) who belonged to the Information and Telecommunications Department of Tohoku Electric Power.
[Proposers’ remarks]
From the line of the Reference text written in Japanese marked with a yellow marker, we can see "Shinobuyama relay station, Japan’s first to use solar cells (began operation) on November 1958."
[8] Kahoku Shinpou, newspaper, November 10, 1958, (in Japanese)
[Translation of the article]
Solar-powered Radio relay station has been built
- on top of Mt. Shinobuyama in Fukushima city
Tohoku Electric Power has been building a solar-powered robot radio relay station on the mountain top of Mt. Shinobuyama. It finished the test on site on the 6th, and will start the operation after the government agency check on 14th.
The use of solar power has been implemented in heat engine and electric power generation, and Nippon Electric Company (headquarters in Tokyo) has successfully produced solar cells domestically, and as its first application, the robot radio relay station used its as its electric power supply.
This radio relay station has been built to augment the radio communication of patrol cars of the Tohoku Electric Power Fukushima office, which is partially blocked by Mt. Shinobuyama. The station is equipped with solar power cells as its power supply, alkaline rechargeable battery for nighttime use, relay transmitter, radio units for motorcycles, etc.
Solar panel uses 4320 solar cells, each measuring 28 mm in diameter. The total output is 60 Watts. 9 such cells are grouped and embedded in acrylic resin block. These blocks are laid on a steel frame measuring 2 x 2.5 meters. Main transmitter and transmitters on motorcycles use transistorized radio units.
A radio relay station with solar cells of such large capacity is the first in Japan and in the world. If the effect of climate conditions is somehow resolved and silicon chips are mass produced, there will be many applications of solar cells.
[9] Asahi Shinbun, news paper, November 2, 1958. (in Japanese)
[Proposers’ caution: note the technical inaccuracies of this article meant for the general public.]
First use of Solar power.
Radio relay station on top of Mt. Shinobuyama.
Dispatch from Kawasaki:
A radio relay station that uses solar power for the radio units will be completed on the 4th on top of Mt. Shinobuyama (273 meters high) in Fukushima city.
NEC Tamagawa Works located in Shimonumabe; Kawasaki city has been conducting research with Tohoku Electric since last summer. This is Japan's first such attempt to use solar power.
Fukushima office of Tohoku Electric dispatches messages to about 70 patrol cars for the repair and maintenance of power distribution via short wave radio. However, its reach was short and very inconvenient. So it plans to use this relay station of output power of 0.5 W and intends to facilitate communication efficiency. The relay station on the top of the mountain can cover the range that is covered by a station of 50 W output on the ground level flat plane. This new relay station does not require a power supply line, and no emergency backup power supply is necessary during typhoon season (in case the grid is cut off).
Five thousand solar cells made of silicon measuring 20-30 mm are laid on a metal plate (2 x 2 meters). This plate is placed on the roof and the solar light generates electricity. During the night and when the weather is bad, the standby rechargeable battery charged from the solar cells is used, and even if rain keeps falling for a month, the station will operate.
The relay station is automated, and maybe once every two years, the liquid in the rechargeable battery requires checking. So the manpower is very much saved.
Radio units are transistorized to reduce power consumption. Two transistor radio units are installed on the top of Mt. Shinobuyama, and another unit is installed in the base station in
the urban area. It uses 150MHz FM communication method, and the testing will be finished by 8th, and Tohoku Radio Regulatory Bureau will plan to test and certify them on 14th.
Comment of Murobuse, Manager of radio equipment at NEC: There are similar reports in the USA. However, the use of transistor radio units is rather rare. This has been a prototype test case, and so it cost a lot. However, the cost of solar cells will come down after a mass production in the future, and they will be used in many radio relay stations like this one.
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