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Advanced Lightweight and Flexible Array with Mechanical Architecture

Periodic Reporting for period 1 - ALFAMA (Advanced Lightweight and Flexible Array with Mechanical Architecture)

Reporting period: 2018-11-01 to 2019-10-31

More and more missions require power supply > 25 kW such as solar electrical propulsion and high throughput satellites. However, the restricted volume between the fairing and the spacecraft sidewall limits the number and the dimension of rigid solar panels during launch. Therefore, the answer for this growing power demand lies neither in stacking more rigid solar arrays, nor by marginal efficiency improvements on III-V multi-junction solar cells, but rather in innovative/disruptive photovoltaic solutions.

To answer this challenge, more solar capacity per volume are needed in stowed configuration, and flexible solar arrays are the only answer for this high-power challenge.

In this context, ALFAMA project brings answers for the mass, the cost and the power challenge, with ambitions at each level of the solar array:
- The mechanical architecture of a lightweight modular deployment system
- The photovoltaic assembly fabrication process, with printed harness & lamination for easier integration, manufacturing and high voltage protection
- The photovoltaic array structure, with thin flexible layers for high power/mass & power/volume ratio
- The solar cells, with the development of highly efficient and ultra-thin lightweight III-V cells using inverted metamorphic and epitaxial lift-off processes.

ALFAMA's drastic improvements will enhance the EU space sector competitiveness, enable new missions and build synergies between space and non-space activities.

ALFAMA brings together a team of 8 partners, leaders in their field, from 3 EU-member states, who will join their efforts towards the realization of a disruptive solar array technology.
Here is an overview of the tasks performed from the beginning of the project.

WP01: Project’s specifications have been made to lay the foundations of the project and to move forward the project goals. These specifications concern:
- Lifetime requirement
- Performance requirement
- Environmental requirement
- Design and manufacturing requirement
- Technical requirement, such as :
- solar cells architectures (dimensions, grid layout, metal contacts, etc.)
- photovoltaic array flexible design (electrical & mechanical)
- mechanical structure and deployment mechanism,
- system-level to analyze ALFAMA’s technology impact (satellites and launchers levels).

WP02: The first thin-film solar cells were subsequently developed and improved. The realization of a mechanical dummy has started to in order to carry out assembly tests

WP03: Flexible photovoltaic modules processes development has started. Different tasks are being conducted :
- The Identification and benchmark of adapted polymers to stick cells on substrate
- The design of a new interconnector for the spatial environment
- The adaptation of standard terrestrial lamination process for spatial flexible PV module
- The development of a printed harness module with specific bill of material and interconnections processes

WP04: Study of a development plan for the ALFAMA solar array has been started

WP06: A website and social media have been created as well as flyers and posters related to ALFAMA project, to facilitate the dissemination of the project first results. The website and social networks are updated each week with new publications.
The ambitious specifications showed the progress compared to the state of the art of the ALFAMA structure.
The progress beyond state of art was initiated by the partners with their work on the design and the first prototypes. Many advances have been made, particularly with the first thin and ultra-thin lift-off solar cells. In conjunction with this, the development of the first flexible substrate with printed conductive tracks adapted to innovative cell geometry was achieved. All these advances are aimed at achieving several KPIs:
1/ Power/mass ratio increased by ≥ 50% with III-V lift-off solar cells and a novel mechanical architecture
2/ Cost reduction with high throughput the assembly process
3/ Power density increased more than 3 times with compact stowed configuration
4/ Relevant roadmaps for space & non-space applications

ALFAMA's drastic improvements will enhance the EU space sector competitiveness, enable new missions and build synergies between space and non-space activities.
Flyer and Poster