In the context of SpaceTech’s support contract with the Taiwanese space agency NSPO for the Formosat-5 spacecraft, SpaceTech signed responsible for the layout and delivery of the solar generator of the spacecraft. Formosat-5 is an Earth observation satellite mission with a ground resolution of approximately 2 m, realized as a Taiwan domestic development.

The solar generator system consists of two nearly identical panels with photovoltaic assemblies that are deployed in orbit. The development of the solar generator is strongly connected with the contracted delivery of an omni-directional sun sensor (OSS) using the same type of cells and substrate and being partially integrated into the solar generator panels, as well.

Each of the 2 panels on the spacecraft consists of 19 strings of 20 cells each. In addition thermistors are implemented on the back side of the panels to allow off-line on-ground performance tracking of the solar generator.

Formosat-5 Solar Panel String Layout & DimensionsFormosat-5 Solar Panel String Layout & Dimensions

Second generation AZUR GaAs triple-junction cells with a rated efficiency of approximately 26 % are used to make up the photovoltaic assembly. Each cell is protected with a by-pass diode and each solar string by a blocking diode.

Formosat-5 Solar Generator Performance SummaryFormosat-5 Solar Generator Performance Summary

The two proto-flight models were delivered to Taiwan in the spring of 2012 and and Formosat-5 has been successfully launched on the 24th of August 2017 from Air Force Base Vandenburg on a Falcon 9 (SpaceX). This is a major milestone both for NSPO as being the first earth observation satellite being designed by Taiwan and for STI as a provider of cost efficient high quality satellite systems.

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