INTRODUCTION
The major goal of the PV industry nowadays is to lower the cost of solar photovoltaic electricity. This can be realized by either increasing the efficiency of the PV modules, or by reducing their production cost.
The vast majority of the PV-market still consists of (p-type) crystalline silicon (x-Si) PV. In x-Si modules, solar cells are usually interconnected in strings by tabs soldered to the front side of one cell and the rear side of the adjacent cell. Due to the limited width of the tabs, such interconnection leads to additional resistive losses. A promising option to reduce the resistive losses in the interconnection is by using an metal wrap through (MWT) concept, as shown in a recent review on this concept[1]. The MWT cell design places all the electrical contact points on the rear side of the cell. This is realized by bringing the emitter metallization via small holes (vias) through the wafer to the rear side of the cell. Compared to H-pattern processing, in the ECN approach the only additional cell process step is drilling the vias. This means that the
ECN process can easily be installed as an update in most modern x-Si cell production lines.
To fully benefit from the MWT design, we developed interconnection based on conductive foil. In this process, cells are not interconnected by soldering tabs to the cells, but by a conductive back-sheet . Cells are placed on the structured conductive back-sheet which connects the emitter contacts of one cell to the base contact of the
adjacent cell and at the same time acts as the back- sheet of the module