Solar Cells

DESIGN AND MANUFACTURE OF SOLAR ARRAYS

• 2015 р. – R&D “Development of design materials for the Sich-2M solar array”.
• 2016 р. – R&D “Development of technical specifications on solar cells panel. Development of a technical design for the solar cells and control-verifying equipment for Sich-2M space craft. Manufacturing and priority testing of mock-up samples of solar cells”.
• 2017 р. – R&D “Development of explanatory note to draft design for the solar cells and control-verifying equipment for solar cells of the geostationary platform of communication satellite”.
• 2018 р. – R&D “Development of an explanatory note to the technical design for the solar cells and verification equipment complex solar cells of the geostationary platform of the communication satellite.”
• 2017 р. – 2018 р. ‑ R&D “Development and manufacture of a solar battery flight kit for the YuzhSat microsatellite class”.
• 2017 р. – 2018 р. ‑ R&D “Development and manufacture of a flight kit of solar cells for the YuzhSat spacecraft of the Microsatellites class”.
• 2017 р. – 2018 р. ‑ R&D “Development and manufacture of a flight kit of solar cells for the spacecraft” GS-1 “class CubeSat”.

MAIN RESULTS OF DEVELOPMENTS:

1. The company LLC «RPE «LTU» in the design for the first time in Ukraine in the solar cells used high-efficiency cells company AZUR SPACE (Germany) with an efficiency of 30%. AZUR SPACE type 3G30A cell is a triple junction gallium -arsenide solar cells with an external protective diode mounted, with welded silver-coated covar foil leads and bonded protective glass.

Silver-coated covar foil interconnects are more resistant to thermal cycling than pure silver foil interconnects. Such interelement connections are especially necessary for solar cells with a period of active existence of 5-7 years in small orbits, where the solar cells experiences tens of thousands of thermal cycling effects.

2. The recommendations of international standards and our own experimental and theoretical results of work on substantiating choice of materials, components and electrical and radio products intended for the manufacture of modern batteries for solar spacecraft development are summarized, and the optimal cooperation of their manufacturers and suppliers is determined.

3. New design-technological and layout solutions for solar cells of large sizes for the Sich-2M spacecraft and the GSS spacecraft were developed, which made it possible to significantly simplify the process of assembling individual solar cells sections, consisting of parallel strings of photoconverter cells, and assembling the solar cells as a whole. At the same time, compared with the parallel-series method of connecting photoconverters in groups, which was previously used in the company, with new solutions for assembling the solar cells, the design of technological equipment is greatly simplified, labor intensity is reduced and the time required for assembly operations is significantly reduced (by 24%) due to a decrease in number of welded joints. Also, the reliability and quality of manufacturing of photoconverter groups is increased (100% quality control of assembly and photoelectric characteristics of photoconverter cell groups).

4. In 2018 design and technological solutions have been developed and solar cells have been created for YuzhSat spacecraft of the Microsatellite class and spacecraft GS-1 of the CubeSat class as part of the implementation of the « Program for the Development of Satellite Technologies of Yuzhnoye Design Bureau for the period from 2015 to 2023»

Basic principles of research, development and manufacturing of solar batteries are based on in-depth analysis of existing design and technological solutions for solar cells from the world’s leading manufacturers for small and ultra-small satellites. During the development of the solar cells, materials and components were selected that have a successful and long-term flight history, fully comply with the requirements of ECSS-E-CT 20-08C and ECSS-Q-70-71A and have passed deep certification on Earth and in space. The technology of their manufacture has been worked out.

Based on the obtained positive results of autonomous experimental testing of solar cells prototypes, three standard solar cells samples for the YuzhSat spacecraft were manufactured and handed over to the customer, including solar cells 1 – 2 pcs, solar cells 2 – 1 pc. Four standard solar cells samples for the GS-1 spacecraft were manufactured and handed over to the customer, including solar cells 1 – 2 pcs., solar cells 2 – 2 pcs. A complete set of working and operational documentation was handed over.

As a result of the performed design and calculation work and the applied new technical solutions, improved technical and economic results for the creation of modern solar cells were obtained in comparison with the previously existing technologies for the manufacture of domestic solar cells for space purposes.

Advantages of solar cells assembly processes based on industrially manufactured cells of the 3G30A photoconverter compared to solar cells assembly processes based on unprotected photoconverters:

• no additional separate purchase, input control and installation with accompanying input control of diodes, protective glasses, adhesive for gluing glasses and interconnections for the photoconverter is required;
• reduction by three times of technological control operations and checks of photoelectric parameters of the photoconverter during the assembly process;
• ensuring optimal layout and assembly processes of solar cells sections identical in configuration;
• each solar cells section is assembled in the form of strings of photoconverter cells connected in parallel in accordance with the required configuration of the electrical circuit. Each string, in turn, consists of several groups of photoconverter cells connected in series with the help of transitional current-carrying tires with the configuration of the electrical circuit of the groups of photoconverter cells from 5S1P to 7S1P that is optimal for assembling;
• the new technology used significantly simplifies the solar cells assembly processes and provides 100% assembly quality control and 100% control of the photoelectric parameters of photoconverter cell groups;
• solar cells design and solar cells manufacturing technology provides high manufacturability in manufacturing, does not require large labor, material and time costs for preparing production and manufacturing a set of solar cells.

1. The area specific power of the new solar cells has been increased by 25% compared to the solar cells based on the previously existing technologies.
2. The labor intensity of manufacturing new solar cells compared with solar cells based on previously existing technologies is reduced by 30%.

The main electric power characteristics of new variants of the solar cells for the spacecraft developed by Yuzhnoye State Design Office

Table 1 – Comparison of the electrical parameters of the solar cells options at end of life (EOL)

Parameter	Option SC
Electrical circuit configuration	43S5P «МС-2-8»	18S4P* «Sich-2M»	19S8P* «GSS»	<7S8P* solar cells 1 «YuzhSat»	7S1P* solar cells 1«CubeSat»
I  work, А	2,25	15,36	44,73	4,06	0,51
Uwork, V	34,0	33,8	35,7	14,0	14,2
Pwork, W	76,5	519,2	1598	56,7	7,25
Pwork, W/m2<	191,0	236,7	233,6	270,0	278,0

* Based on the use of highly efficient 3G30A photoconverter cells from AZUR SPACE (Germany) with an efficiency of 30%.

DESCRIPTION OF CAPABILITIES (AVAILABLE SERVICES)

SPACE SOLAR ARRAYS ON RIGID CARBON-FIBER PANELS FOR SMALL AND ULTRA-SMALL SPACECRAFTS