Abstract: An apparatus is provided for forming a large area photovoltaic cell into a plurality of photovoltaic cells on a common substrate and preparing the individual cells for an overlying layer of conductive material. A tool bit is urged against the polycrystalline materials forming the heterojunction to remove a preselected pattern and expose a layer of conductive material, tin oxide, on a supporting glass substrate. Tool bit pressure causes fracturing of the crystals to produce defined edges along the tool bit furrow. An electrical arc is produced to vaporize a portion of the exposed tin oxide to electrically isolate the individual photovoltaic cells. Applicator pens coat the edges of the polycrystalline material with preselected insulating films. Finally, a buffer wheel abrades a preselected metal onto the remaining exposed surface of the tin oxide to obtain an improved metallurgical and/or electrical contact between the tin oxide and the subsequent conductor layer.