This paper studies the performance of hyperdense large-scale cellular networks with energy harvesting. To combat the randomness of renewables, the base stations (BSs) with the harvested power larger than the predefined power target are assumed to cooperatively share their surplus power to the BSs with insufficient energy via directed microwave power transfer (MPT). To evaluate the performance of the proposed cooperative power sharing scheme, a new performance metric, namely the power coverage probability, which is defined as the probability that a BS satisfies its respective power target, is introduced and then characterized by applying tools from stochastic geometry. It is shown that in the hyperdense regime, the power coverage probability of cellular networks with energy harvesting and MPT based power sharing depends on the statistical mean of the harvested renewables, the power target, the power sharing distance, and the MPT path-loss exponent. Simulations are provided to validate our analysis.