# AC Coupling vs DC Coupling: Where Should PV Connect? Neither is "better" — they fit different project conditions. A practical comparison of AC vs DC coupling with VGRID MPPT/DC-DC options. One point decides it: does PV connect to the AC or DC bus? AC coupling Most common for retrofit: PV modules → PV inverter → AC bus, battery ↔ PCS → AC bus → loads/grid. **Pros:** easy retrofit, flexible expansion. **Watch:** PV-inverter coordination with microgrid grid-forming / anti-islanding. DC coupling For new systems / higher PV DC utilisation: PV → MPPT → DC bus, battery ↔ PCS → AC bus. **Pros:** PV and battery share the DC side, fewer conversion stages. **Watch:** DC voltage matching and MPPT/PCS power sizing. Selection principle Retrofit → AC coupling; new microgrid wanting modular, near-array PV → DC coupling. VGRID [Leona-M200K](/en/product/sp200-150hapv) and [SP120/60HCPV](/en/product/sp120-60hcpv-sp105hcdc) move MPPT to the array side to cut long PV cabling. When to use DC/DC When the challenge is "how to connect different battery voltages to one DC bus", a bidirectional DC/DC such as [SP210HCDC](/en/product/sp210hcdc) decouples voltage and manages clusters independently. ## Is AC or DC coupling better? Neither absolutely. Retrofit favours AC coupling; new microgrids wanting modular near-array PV favour DC coupling. ## What MPPT does DC coupling need? Boost/buck MPPT (Leona-M200K, SP135HAPV) matched to PCS power and DC voltage, with multi-string combiner. ## How to connect different-voltage battery clusters? Use a bidirectional DC/DC (SP210HCDC) for voltage decoupling, independent cluster management and SOC balancing. ## Where is anti-backflow more critical? Both need it; AC coupling relies on meter + EMS strategy, DC coupling also needs DC-side protection.