CIGS Solar Cells

Discover the power of CIGS solar cells engineered to redefine space power.
With a unique monolithic structure on a glass substrate, our CIGS solar cells offer customizable electrical characteristics to perfectly suit your mission's needs.

CIGS stands for Copper Indium Gallium Selenide, a compound semiconductor that efficiently converts sunlight into electricity. These solar cells belong to the thin-film category, meaning that the active photovoltaic layer is deposited as an extremely thin film on a supporting substrate. Thin-film cells are produced using industry standard methods which enable the fabrication of lightweight, and cost-effective solar modules.

Our CIGS solar cells maintain their conversion efficiency even under intense radiation exposure. A combination of thermal annealing and light-soaking allows the cells to heal themselves against the damaging effects of radiation.
In LEO orbit, it has been observed from flight data that CIGS solar cells are able to retain their beginning of life efficiency through a 900 day mission without coverglass¹⁾. Additionally, in another flight test, they were shown to outperform 2J-GaAs cells in a 600 day geostationary transfer orbit^{*1, 2)}. CIGS solar cells are so radiation resistant that they don’t require cover glass for protection, reducing mass and optimizing specific power.^​​

<Fig.①Radiation‐Induced Efficiency Degradation: CIGS vs. Space‐Grade Silicon Solar Cells>

The CIGS solar cells have a BOL efficiency of 17% and the space‐grade silicon have been advertised to start at 19%. These two curves intersect at an equivalent electron fluence of approximately 3×10¹³ electrons/cm², corresponding to about six months of orbital exposure. Beyond that point, the CIGS solar cell maintains higher efficiency, demonstrating its greater resilience compared to silicon for longer‐duration missions like 5 years operation in LEO.

Our advanced thin-film manufacturing process allows the formation of 30 cm by 30 cm solar cells on a single glass substrate, reducing the number for interconnectors^*2) that can compromise reliability due to thermal cycling and electrical failure. This design not only simplifies manufacturing but also maximizes the active area of the cell. 

<Fig.➁　Solar Cell Layout Image>

With a 17% conversion efficiency as shown in Fig.①, and no need for cover glass, our CIGS solar cells offer the highest power-to-weight ratio in space solar technology as shown in Fig.③^*3. This lightweight, high-output design makes them the perfect power source for constellation satellites and lunar exploration vehicles.

<Fig.③　Power-to-Weight Ratio>

Developed by Solar Frontier, a wholly owned subsidiary of Idemitsu, our CIGS solar cell technology is backed by over 30 years of research and development.
We’re proud to be one of the world’s leading producers of this technology. As a terrestrial solar power business, we have achieved a conversion efficiency of 23.4% (AM1.5).

Idemitsu has a 10,000ft² (1000m²) R&D manufacturing facility for cell fabrication, testing, and analysis.