# C&I Energy Storage Design: From Self-Consumption to Peak Arbitrage C&I PV-storage needs daily self-use and automatic load carry during outages. Configuration, SOC strategy, anti-backflow and VGRID PCS/all-in-one options. Configuration goal Daily self-consumption and peak-shaving plus automatic load carry during outages; diesel (if any) auto-relays at low SOC. Typical configuration paths **Retrofit PV (AC coupling)**: keep existing PV inverter, add [PCS](/en/product/sp125hcps) or [all-in-one](/en/product/sp250hag2t-2) charging/discharging per EMS. **New PV-storage (DC coupling)**: [MPPT](/en/product/sp200-150hapv)+[DC/DC](/en/product/sp210hcdc) for DC-side combiner, fewer stages. **High backup need**: built-in/standalone STS for <10ms/<20ms transfer. SOC and strategy EMS runs self-use, peak arbitrage, backup and anti-backflow by SOC bands; [undefined](/en/page/commercial-industrial storage) pairs with [undefined](/en/page/grid-forming/weak-grid) capability. Use cases: factory/park backup, PV-charging, construction/emergency. ## How large a C&I storage? Size by daily load curve, tariff spread and backup duration; from hundreds of kWh to MWh. Do a load/PV assessment first. ## Is anti-backflow mandatory? Required where export is prohibited — via meter + EMS strategy to avoid penalties and grid impact. ## Key to peak-arbitrage revenue? Tariff spread, round-trip efficiency (PCS/system) and battery degradation; EMS executes by tariff time function. ## All-in-one or PCS for factory backup? Standard skid delivery → all-in-one (H54PSSTD); modular expansion or OEM → PCS module (SP125HCPS).