CESI – Centro Elettrotecnico Sperimentale Italiano “Giacinto Motta” S.p.A.

CESI, among its energy businesses, has also over 30 years’ experience in the research, development and production of high efficiency multi junction solar cells for civil space applications based on our own proprietary technology and our own manufacturing facility in Milan, Italy, being one of the four global suppliers of such class of space cells with a flight heritage of more than 80 satellites for clients from over 25 different countries worldwide .

Our triple junction cells, based on GaAs compound semiconductors, are characterized by high power conversion efficiency, radiation hardness and reliability in the harsh space environment.

Solar cells are manufactured at our own facilities in Italy and we can provide them at either bare or Solar Cell Assembly (SCA) also known as Coverglass Integrated Cells (CIC) level. CESI focuses on the manufacturing of cells only - which we then supply to the specialized integrators of space solar modules and/or whole satellites. We believe that our exclusive focus on the cell, which is a very peculiar high-technology component, provides more flexible collaboration opportunities with PVA/SA/Satellite integrators.

CESI is particularly proud of our distinctive positioning based on the capability to shape and fine-tune our solar cells with respect to the technology and to the cost vs performance mix to the precise application needs of a customer’s specific space mission.

The current product portfolio of triple junction (InGaP/GaAs/Ge) for civil space applications is listed below:

1)    Triple-Junction Solar Cell (CTJ30)

The CESI Standard space Triple Junction solar cell named CTJ30 is qualified for LEO and GEO missions and have to date powered more than 60 satellites.

Features & Characteristics (bare level)

• 29.5% efficiency at AM0
• Very low solar cell mass (81-89 mg/cm2)
• Thickness 150 μm
• Fully qualified (bare and SCA) according to ECSS E ST20-08C for LEO and GEO orbit
• High Radiation Resistance

2)    Low Cost Triple-Junction Solar Cell (CTJ-LC)

The Low Cost solar cell named CTJ-LC is qualified for LEO and GEO and supports the achievement of costs/prices 30% lower than current commercial market levels, being especially suitable for the new mini/micro/cube satellite constellation emerging market where the costs are key. More than 24 satellites are powered with CTJ-LC-SCA gaining flight heritage since 2017 in LEO mission without any problem reported so far.

Features & Characteristics (bare level)

• 28% efficiency at AM0
• High radiation resistance
• Higher volume production capacity
• Fully qualified (bare and SCA) according to ECSS E ST20-08C rev.1 for LEO and GEO orbit

The new CTJ-LC2 version (efficiency 27% @ AM0), with price towards 50% lower than current commercial market levels, is already available.

3)     Thin Triple-Junction Solar Cell (CTJ-thin)

The Thin triple junction solar cell named CTJ30-Thin (bendable) maintains the high quality features and the electrical performances of CTJ30, while reducing of about one half the whole cell thickness. These cells are aimed at the New Generation Array (NGA) designs requiring flexibility features.

Features & Characteristics (bare level)

• 29% efficiency at AM0
• High Radiation Resistance
• Thickness 80 μm
• 50 mg/cm2 mass
• >0.7 W/gr (power-to-mass ratio)
• Qualified according to ECSS E ST20-08C rev. 1 for LEO and GEO orbit (qualification at SCA level pending).

4)   Large Area Triple-Junction Solar Cell (CTJ-LA)

The Large Area space products (size 6 cm x 12cm, active area > 68cm2) comprise the CTJ30 (large area version named CTJ30-LA) and the CTJ-LC (large area version named CTJ-LA) maintaining their high quality features and the electrical performances.

The new CESI Product CTJ30-LA and CTJ-LC-LA are interesting for the space market in different applications:

• CTJ30-LA are particularly suited for those missions in which a very high power is requested (both BOL and EOL) (typically GEO telecom satellites),
• CTJ-LC-LA are interesting for the commercial market (Telecommunication, earth-observation, Internet, IoT, etc) where the competitiveness is more toward the cost,

and in general for all those missions in which the solar arrays are requested to be increasingly lighter and cheaper and more efficient, while maintaining their high reliability.

The CTJ30-LA and the CTJ-LC-LA are currently under qualification at bare and SCA level.

Features & Characteristics (bare level):

• CTJ30-LA:  Efficiency 29% at AM0, BOL;  Thickness 160 µm ± 20µm
• CTJ-LC-LA: Efficiency 28% at AM0, BOL; Thickness 180 µm ± 20µm
• Qualification according to ECSS E ST20-08C rev. 1 ongoing
• High Radiation Resistance
• Lower manufacturing costs per cm^2 at cell level
• Lower assembly costs at solar generator level Space saving at solar generator level