Development of Shingle-Matrix Silicon PV Modules for LEO and GEO Satellites

Source Energy and Fraunhofer ISE have developed a new concept for resilient space solar power. By combining silicon-based solar cells with innovative shingle-matrix interconnection technology, they've engineered modules that withstand micrometeorite impacts, extreme temperature swings, and still deliver 76% of their original power after seven years in orbit – opening new possibilities for cost-effective LEO (low earth orbit) satellite missions.

Initial Situation

Source Energy wants to overcome current long-lead availability and high prices for solar arrays in space. With the support of Fraunhofer ISE they therefor replaced III-V solar cells – the current standard for solar cells in space applications – with silicon solar cells in their solar modules and arrays.

Silicon wafer-based technology dominates the terrestrial market with a share of 95%. Given their high availability at low costs, silicon solar cells show great potential for space applications, like LEO satellites, for example, where balancing costs and efficiency as well as long term stability play a major role.

Objective

Source Energy reached out to Fraunhofer ISE in 2023 to

• further improve on the quality and resilience of their PV modules and arrays 
• further cut costs by setting up a semi-automated production line.

We tackled that task with them by introducing a new cell interconnection technology based on matrix shingles. For this technological approach individual solar cells are cut into strips and arranged with certain slight overlaps and staggered with relative spacing to one another, like brickwork. An electrically conductive adhesive bonds the solar cells together.

Three advantages make the shingle-matrix interconnection a perfect match for space: The matrix structure allows current to flow around damaged areas making it resilient to hits from small meteorites or space debris. The matrix structure also allows a high flexibility in layout, making a variety of module and array sizes possible. In addition, the interconnection via conductive adhesive is more tolerant to the extreme temperature differences present in space than traditional wire interconnections are.

Approach

Fraunhofer ISE developed solar modules, small and big solar arrays for space applications with Source Energy, all using the shingle-matrix technology and helped with the line planning for the module production. German equipment manufacturer M10 Solar Equipment delivered a shingle-matrix stringer as core system to the new manufacturing line.

For the matrix strings Fraunhofer ISE made sure to use only materials that maintain their performance in harsh space conditions. Source Energy tested the module prototypes thoroughly for space readiness (see graphic). The tests confirms that Source Energy’s PV modules and arrays can be expected to deliver 76% of their original power output after seven years in space.

Results

The resulting solar modules are compact and lightweight: with 64 grams and 629 square centimeters, (321 by 209 millimeters). The average power output of the prototypes was 15.6 watts—with modules achieving 16.1 watts—and an average active area efficiency of 18.8 percent (AM0 at 25°C). The module carries a specific power of 244 watt per kilogram on average and reaching 252 watt per kilogram, which makes it competitive to silicon module in its class.

Thanks to the new module design and the semi-automated production line, Source Energy is able to save significantly in manufacturing costs and offer to their customers delivery in less than six months from the time of order for solar modules and smaller arrays.

Shingle-matrix solar modules are planned for flight in early 2027 providing LEO satellites with reliable solar power.