European Space Agency

SA Building Blocks - GaAs Solar Array Family Building Blocks developments ESA/ESTEC Contract No. 21588/08/NL/US


This project raised when GaAs triple junction cells competitiveness was identified with regard to silicon heritage. Objective of this project was consisting in the qualification of building blocks at CIC level and PVA level for GEO application, following PVA ECSS guidelines for 2 configurations of network.

The qualification has been successfully passed for :

  • GaAs 3J 28% network based on 3G28 bare cell
  • GaAs 3J 30% network based on XTJ Leone bare cell



The technical objective of this project was first to qualify CIC and PVA assuming an already available set of qualification tests at bare cell, by-pass and coverglass level, as it was identified at corresponding EQSR. The qualification was doubled and has dealt with two configurations.


Large GaAs cells provide a very competitive and efficient solution for GEO satellites.


Development has been broken down into 3 phases to introduce gradually, products of increasing performance and competitiveness on the GEO Solar Array market :

First a qualification of the 3G28 bare cell based on triple junction GaAs of 28% BOL efficiency with historical TAS supplier for PVA laydown in order to obtain risk limited solution versus industrial breakdown.

Secondly a qualification based on confidence reached on constellation products transcribed for GEO application. This solution of design to cost for constellation is based on large one-per-wafer “Leone” cell based on XTJ 30% BOL GaAs triple junction.

Thirdly, in parallel to this project, access to first application program using the 3G28 European GaAs cell network was provided with a synthesis of all the upper level PFM tests till wing level. In the frame of the XTJ Leone cells a dedicated Artes development was initiated at wing level, with a QPFM panel, built to validate full scale manufacturing process.

Technical objective of this project was to build a qualification following worldwide recognized ECSS standard and generic to cover all GEO applications. The PVA qualification has authorized to sell first application programs with a single PFM approach.


The following table summarize the qualified configurations :
Coupon# :


A quick phase 1 has enabled to consolidate the development plan.

Then, phase 2 was initiated to pursue the following activities :

  • 3G28 PVA qualification
  • TAT for 3G28
  • ESD for 3G28
  • XTJ Leone PVA qualification
  • ESD for XTJ Leone

Compatibility verification of XTJ Leone and 3G30 on alternate substrate

Current status

The project is now finalized and 16 satellites have benefit from these new PVA developments.

Status date

Tuesday, April 19, 2016 - 08:21