# What Makes Up a Microgrid? PCS/BMS/EMS/MPPT/DC-DC/STS Roles Read a topology by finding the bus, then energy inputs, then control lines. A clear map of microgrid component roles and coordination. The trick to reading a system In a topology, first find the bus (AC/DC), then the energy inputs (PV/grid/diesel/battery), then the control lines (EMS/BMS). Each component owns one core job **PCS**—battery↔AC bus, bidirectional / grid-forming / transfer (e.g. [SP125HCPS](/en/product/sp125hcps)). **BMS**—battery safety/state: SOC/SOH/temperature/protection. **EMS**—system dispatch: strategy / coordination / cloud. **MPPT**—PV→DC bus, max-power tracking (e.g. [Leona-M200K](/en/product/sp200-150hapv)). **DC/DC**—DC↔DC, buck-boost / cluster management (e.g. [SP210HCDC](/en/product/sp210hcdc)). **STS**—grid↔off-grid fast transfer, less downtime (e.g. [STS200/400/600](/en/product/sts200-400-600)). **ATS**—grid↔diesel transfer/interlock. **Meter**—power/voltage/current measurement, anti-backflow basis. Control flow = EMS comms EMS communicates with PCS, BMS, STS and diesel to unify energy dispatch. VGRID covers modules ([PCS](/en/product/sp125hcps)) up to [MW-class switch cabinet](/en/product/sp1350h54sw). ## Does a microgrid need an EMS? For self-consumption, peak-shaving, backup and multi-source coordination, EMS is the dispatch layer; simple backup can run on STS+PCS internal strategy. ## BMS vs EMS? BMS manages cell/cluster safety and state; EMS manages system energy strategy and coordination — distinct roles. ## ATS vs STS? ATS switches grid↔diesel; STS does millisecond grid/off-grid transfer to cut critical-load downtime. ## Does VGRID supply the full component set? Yes — PCS, MPPT, DC/DC, STS, EMS plus all-in-ones and MW switch cabinets, modular or skid delivery.