With the ever-increasing distributed photovoltaic(PV)connection in the regional distribution network

the reference group of PV penetration indices has become a crucial guidance for rational planning of distributed PV. Ignoring the distribution network upgrading

the PV power penetration(PP)

capacity penetration(CP)and energy penetration(EP)are analyzed to establish the reference group of PV penetration indices. On the basis of a physical regional distribution network

the physical meanings of PV penetration indices are explained

and the relationship between the PV output

PV cost

PV utility ratio when connected to the distribution network are discussed. The influences of different load types on PV penetration indices are also analyzed. The PV penetration indices will provide a guidance and reference to the planning and investment in distributed PV connection to effectively guide the future coordinated development of distributed PV and grid.