The power flow formulation based on current injection was first introduced to cope with the problem of updating the Jacobian matrix in the conventional Newton Raphson power flow. In the case of PQ buses, the current injection method is very efficient, as all elements in the Jacobian matrix are constant. However, when PV buses are present, non-constant elements are introduced in the Jacobian matrix, deteriorating the methodôs performance. This paper presents a novel approach for representing PV buses in the current injection power flow by applying the concept of single-phase phasor rotation. In the proposed formulation, the elements introduced in the Jacobian matrix by the presence of PV buses are constant; therefore, the Jacobian needs to be built and factorized just once, reducing the computational burden and speeding up the power flow solution process. Case studies were conducted on transmission and distribution systems containing up to 2313-buses, considering several R/X line ratios and loading conditions to illustrate the validity and merits of the proposed formulation. The results indicate that the proposed approach leads to a computationally efficient power flow that can be successfully applied to single-phase transmission and distribution networks.