Even though in the past the photovoltaic industry was dominated by single-crystalline silicon this days multi-crystalline silicon is consider to be on of the most promising material for application in low manufacturing cost solar photovoltaic arrays, consequently it has a huge potential to dominate the single-crystalline silicon in the photovoltaic industry in the next decades. However the presence of crystal defects such as dislocation and grain boundaries in multi-crystalline solar cells hugely reducing the conversion efficiency of this material compared to single crystalline silicon solar cell. Hence realizing the widespread utilization of this material will require understanding and control of the effects of this defects on the photovoltaic cell performance. Therefor we will examine the local resistivity of a given multi-crystalline sample in a dark and how it is affected by the presence of grain boundaries and the electrical activity when we cross or with in the grain boundary or twin boundaries. We have measured the resistivity of a number of samples of multi-crystalline silicon using a multi-height four-point probe.