The Spatial Only Processing Power Inversion (SOP-PI) algorithm is frequently used in Global Navigation Satellite System (GNSS) adaptive array receivers for interference mitigation because of its simplicity ofimplementation. This study investigates the effects of SOP-PI on receiver measurements for high-precisionapplications. Mathematical deductions show that if an array with a centro-symmetrical geometry is used, ideally, SOP-PI is naturally bias-free; however, this no longer stands when non-ideal factors, including array perturbations and finite-sample effect, are added. Simulations are performed herein to investigate how exactly the arrayperturbations affect the carrier phase biases, while diagonal loading and forward-backward averaging are proposed to counter the finite-sample effect. In conclusion, whether SOP-PI with a centro-symmetrical array geometry will satisfy the high precision demands mainly depends on the array perturbation degree of the element amplitude and the phase center.