Nebula Public Library

The knowledge bank of ESA’s R&D programmes

Improved multi-junction solar cells with up to 33% efficiency at end of life

Programme Reference
Prime Contractor
AZUR SPACE Solar Power GmbH
Start Date
End Date
To improve the cost effectiveness of multi-junction solar cells by improving the beginning of life and end of life performance
Establishment of technology non-dependence in the area of solar cell technology has been one of the key successes of the TRP programme in recent years. The current situation is that the marketplace remains extremely competitive. The main concern is that the unless European technology keeps up with competition, especially from US solar cell manufacturers, then European products will not be competitive and technology independence will be lost. Continuity of development remains critical in order to maintain this position.
Further 'delta development' of existing products is not adequate to address either the opportunity to make the most cost effective product, or the threat that a non-European competitor will do so instead.
The added value of the activity will be to maintain technology independence while reducing system level costs. There are several pathways to higher efficiency that require development of different ?technology building blocks? that will result in different products, without one clear winner. Parallel development of several ?technology building blocks? is necessary.
The activity will further develop multi-junction solar cells.
There is an opportunity to increase the key performance metric of ?end of life? solar cell efficiency up to 33% (in comparison with a baseline of 28.5%) by further developing multi-junction cell technology, resulting in a relative performance improvement of 15% and corresponding system level cost benefits. There is also an opportunity to reduce the thickness and mass of the cells by >30%, allowing their integration into lightweight panel structures that are also under development. This will potentially allow doubling of the solar array power to mass ratio and reduction of the in-orbit solar array costs by 30%.
This activity encompasses the following tasks that represent ?technology building blocks? for multi-junction cells:
- upright and inverted metamorphic layer growth
- layer transfer
- Ge substrate technology improvement
- coverglass technology improvement
- introduction of lattice-matched nitride containing layers
- deliverables will include solar cells with target end of life efficiency of 33%
Application Domain
Generic Technologies
Technology Domain
3 - Space Systems Electrical Power
Competence Domain
4-Electric Architecture, Power and Energy, EMC
Initial TRL
Target TRL
Achieved TRL
Public Document
Final Presentation
Executive Summary