RESISTANCE, POWER LOSS, AND ADHESION OF CONTACT TAPES ON CIGS MODULES

摘要

Sn-plated contact tapes were connected to CIGS solar modules and test layers using an optimised epoxy-based conductive adhesive. The tapes were adhered ⅰ) onto ZnO/CIGS/Mo (configuration "S"), ⅱ) onto ZnO/Mo (configuration "Z") and ⅲ) onto the Mo back contact layer (configuration "M") and tested without encapsulation. The peel strength of the contacts was significantly decreased by 1000 h of damp/heat (DH) exposure but not by thermal cycling (TC). The average contact resistance R_c of contact tapes in configuration S increased from about 100 mΩ up to about 1000 mΩ during DH exposure, caused by the increase of the ZnO sheet resistance R_(sq) and the contact resistivity p_c at the interface ZnO/adhesive/contact tape. Configuration Z and M basically enable considerably lower contact resistance values of about 5-10 mΩ without a significant increase during DH exposure. This result is attributed to the low and stable Mo sheet resistance controlling R_c of both configurations and a low contact resistivity ρ_c at the interface. Contacts in configuration M, however, suffer from severe Mo corrosion along the contact tapes. The power losses of solar modules caused by the contact resistance increase with a decreasing number n of cells and are < 0.1% for configurations M and Z. In the case of configuration S, the power losses were estimated > 1% for n < 60 and > 6% for n < 10 after 1000 h of DH exposure.