# PCS Selection Guide: Power / Topology / Paralleling / Off-Grid From system boundary to specs: power class, battery voltage window, grid-forming & paralleling, off-grid backup, with the VGRID PCS matrix. Boundary first, then specs Select by system boundary (grid-tied/backup/fully off-grid, load, battery, PV, diesel, grid stability) before power and specs. VGRID PCS matrix **Small/mid hybrid/storage**: [SP30/25/15HBPS](/en/product/sp30-25-15hbps), [SP60/50/40/30HCPS](/en/product/sp60-50-40-30hcps), [SP100H](/en/product/sp100h). **Standard microgrid module**: [SP125HCPS](/en/product/sp125hcps) (125kW, up to 15 off-grid parallel, grid-forming). **Liquid-cooled / high power**: [SP125HSPS](/en/product/sp125hsps). Key points Power: size to peak/continuous load with overload margin (1.5× is an advantage). Battery window: must cover operating range. Grid-forming/off-grid: no-grid or backup needs grid-forming + STS. Paralleling: modular grouping first, then AC parallel & switch capacity (see [Cambodia 1.5MW](/en/cases)). ## Why is 125kW often the microgrid core module? Standardised, grid-forming, 1.5× overload, up to 15 off-grid parallel, and ≥10-year design life. ## What PCS for a fully off-grid project? Grid-forming PCS (SP125HCPS, Leona-H135K), with paralleling count and diesel coordination assessed. ## How to plan multi-PCS paralleling? Group by cluster management first, then AC parallel & switch capacity; beyond standard, use system-level PCC. ## When is liquid-cooled PCS suitable? High-density, high-current, strict thermal sites — e.g. SP125HSPS.