We obtained 17.9% cell efficiency on thin and large mc-Si REC wafers using ECN's metal-wrap-through (MWT) concept. Optimization of several cell processing steps led to an increase of more than 2% absolute in cell efficiency. With these cells 36-cell modules were manufactured at 100% yield in our industry scale module pilot line. The highest module efficiency obtained (as independently confirmed by JRC-ESTI) was 17%. In this module the average cell efficiency was 17.8%; this shows a small difference between cell and module efficiency. Copyright © 2011 John Wiley & Sons, Ltd.