The objective of the activity is to reduce the cost of advance multi-junction solar cells by reviewing an adapting respective process steps at Ge wafer level, solar cell epitaxy and solar cell processing

 

Solar cell development for space up to now is mainly driven by increasing the power/mass and power/area ratio. Therefore, the main objective in solar cell development is to increase the efficiency of the cell. For those type of products, customers are prepared to accept also higher costs as long as the ?/Watt measure do not increase.

However, especially with the emergence of mega constellation programs, the cost of the cell becomes a relevant parameter. The whole satellite and therefore also the solar generator shall be made as cheap as possible (of course, by meeting some minimum performance figures). In this quite aggressive market, it is important that European space solar cell manufacturers can offer a product which answers to those new demands. Therefore, one of the initial tasks of this activity is to identify all areas with cost reduction potential and develop (in case needed) an adapted process that allows for meeting the requested ?/Watt figures.

Potential areas of cost reduction are found in the complete production chain, starting from the substrates (Germanium wafers), over the epitaxial growth process and finally the solar cell processing. On Ge wafer level, the idea could be, to omit some expensive process steps which then would result in a rougher wafer surface. A dedicated nucleation process would have to be developed in order to limit any detrimental effects on the final product. Furthermore, on epitaxy level one would have to look into higher growth rates in order to increase production throughput. Also during solar cell processing different options shall be investigated in order to safe costs.

 

This activity encompasses the following tasks:

• Review of all process steps in the whole production chain identifying cost reduction potentials

• Defining new process route and modification needs for affected production steps

• Development/Adaptation of processes complying with changes in preceding process steps

• Implementation of adapted solar cell manufacturing process and manufacturing of first low cost prototypes

• Engineering tests