Abstract: With the large-scale application of distributed photovoltaics (PV) in the industrial sector, the penetration rate of PV integration into factory distribution networks has increased, causing problems such as non-compliant power factors and excessive voltage rise on low?voltage busbars. These issues expose enterprises to power factor penalty charges and reduced supply stability. In view of the shortcomings of existing treatment technologies, such as the disconnection between reactive power compensation and voltage regulation, and poor adaptability to reverse power flow conditions, this paper proposes a coordinated control device and method for power factor and voltage in PV grid?connected systems. The device consists of a controller, metering instruments, and auxiliary detection components. It achieves coordinated data acquisition via RS485 communication. Based on a four?quadrant classification of the power state at the low?voltage outgoing node of the transformer, a coordinated control strategy is established combining reactive power compensation and tap?changing of the on?load tap?changing transformer. This effectively resolves power quality issues in PV grid connection, provides an efficient and reliable technical solution for industrial PV power quality management, and holds significant engineering application value and theoretical reference significance.