During the first period, the development of single components has been successfully finalized by completing WP1 (CSJ formation) and WP2 (TCO deposition). In addition, the most tasks of the WP3 (metallization) are ending while all technical targets are achieved so far.
The best components of each work packages have been integrated into solar cells within the WP4 (high efficiency solar cells and modules). By involving four different partners in three different countries, solar cell efficiencies up to 21.2% has been achieved, although each component are not optimized yet. The detailed analysis performed in WP6 (characterization and modelling) pointed out that TCO is the limiting component that needs to be improved to achieve higher cell efficiency. This is because the surface passivation quality of poly-Si based CSJ layers suffers significantly during the TCO deposition step, caused by sputter damage.
The consortium has decided to continue the project work with following three routes:
1. Development of TCO deposition techniques with low sputter damage by keeping same cell design. The additional investigation in WP2 showed that the hydrogen in TCO and the post-annealing step at elevated temperature are the key to recover the sputter damage. By applying these knowledges, the cell efficiency could be increased up to 22.2% with indium-free TCO and silver-free metallization on industrial size wafers.
2. Neglecting the TCO layers by direct metallization on the poly-Si based CSJ layers. The metallization is realized with a lithography step. The proof of the concept has been demonstrated with a cell efficiency of 20.8%, but the radiation damage during the metallization step affected Voc and hence final cell performance strongly.
3. Solar cells featuring poly-Si based CSJ only on the rear side has been evaluated and cell efficiencies up to 22.5 % has been achieved. This cell architecture presents excellent transparency resulting in higher current, however the front side, with no CSJ, appears to be the limited components for the Voc.
The module development has been performed separately with a different cell design in combination with single components developed within DISC project. Optimized encapsulation process on Meyer Burger’s smart-wire technology for half-cells enabled the module power of 322W. Accelerated aging test performed at Meyer Burger on module made with SHJ cells from CEA-INES is so far passing more than 3 times IEC standards.
As part of WP5 (Economical assessment, LCA and social acceptance), the life cycle analysis has been performed by comparing the common cell design with industrial standard PERC and HJT solar cells. The LCA shows that DISC cells with 25% cell efficiency has lower CO2 impact than PERC+. In addition, SHJ has the lowest CO2 impact due to its high cell efficiency and bifacial energy gain. The sensitivity analysis regarding cell production in China versus Europe shows that the production in Europe is advantageous across all categories, except for equal performance for freshwater eutrophication and metal depletion.
WP7 (Dissemination and Exploitation) was focused on disseminating the results from other WPs and support it with communication actions, based on project webpage updates, Research Gate updates, newsletter release and institutional e-mail lists. A common exhibition booth at the EUPVSEC 2019 and a common workshop with Nextbase and Ampere are carried out successfully.
