Enter peak and valley load to size the BESS, PCS and diesel backup, then compare pure grid, pure diesel and diesel+storage economics with a payback estimate.
Shaving power = peak − valley load. The BESS is sized to that power for your shaving hours; the diesel genset backs it up. The ATS handles grid↔genset transfer, an optional STS serves sensitive loads, and DC/DC only applies to a DC-coupled PV-storage topology.
Economics basis (illustrative):Savings assume the BESS charges at the grid price and discharges to displace diesel generation (or a higher peak tariff) at the 0.130 $/kWh spread. Actual payback depends on demand-charge structure, TOU tariffs and cycle life — verify with the local tariff.
Three-option comparison (NPV):10-year NPV (8%): pure diesel ≈$1,371,541 vs diesel+storage ≈$1,137,743 → NPV saving ≈$233,798. Storage wins where the spread is large and daily cycling is regular (illustrative, excludes demand-charge savings).
Peak-shaving strategy:Typical dispatch: BESS charges during valley hours (00:00–06:00) and discharges across the evening peak (4 h/day) to clip the load below the contracted demand ceiling; the diesel genset covers outages and extended peaks.
BMS communication architecture:BMS monitors cell voltage/temperature and estimates SoC/SoH, speaking CAN/RS485 to the PCS and Modbus TCP to the EMS. The EMS dispatches PCS set-points from the load forecast and tariff schedule.
Safety design (thermal runaway):Pack-level fusing, per-pack fire suppression, gas/smoke/temperature early-warning, and container ventilation/containment limit thermal-runaway propagation — per GB/T 36547 and IEC 62933 safety requirements.
Pricing basis:BESS and PCS priced per kWh/kW from the catalogue; BMS from battery-management-systems; diesel genset and ATS from their price references. Thermal management, fire suppression, STS, switchgear, metering and EMS are quoted per project (POA).
Switching chain:The ATS handles grid↔genset transfer; an optional static transfer switch (STS) provides ≤4 ms break-free transfer for sensitive loads; DC/DC converters are only needed for a DC-coupled PV-storage topology (not this AC peak-shaving case).
Operation & maintenance:Routine O&M: cell-balance verification, cooling-system maintenance, fire-suppression functional test, EMS SoC calibration and metering check. Battery cycle life depends on operating DoD and temperature — plan replacement at 80% SoH.
Design review:This is a preliminary sizing. Verify the load profile, demand-charge rules, BESS cycle life at the target DoD, and local interconnection/fire-safety codes.
How it was calculated
Core formulas
Shaving power = peak − valley. BESS energy = shaving power × hours. Saving = shaved energy × (diesel − grid) spread. Payback = BESS CAPEX ÷ annual saving.
The BESS charges at the grid price and discharges to displace diesel (or a higher peak tariff). Payback = BESS CAPEX ÷ annual saving, driven by the diesel−grid spread and daily cycling.
What is the switching chain?
An ATS switches between grid and genset; an optional static transfer switch (STS, ≤4 ms) serves sensitive loads; DC/DC converters are only needed for DC-coupled PV-storage, not this AC case.
Which three options are compared?
Pure grid (buy peak kWh at the grid tariff), pure diesel (fuel at the diesel rate), and diesel+storage (valley charging plus amortised BESS). Storage wins where the spread is large and cycling is regular.
What is priced in the BOM?
BESS and PCS (per kWh/kW) and the genset + ATS are priced from the catalogue. The STS (optional) and EMS are quoted per project.
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Results are engineering estimates for reference. Final design must be confirmed by a licensed local engineer against site conditions and applicable codes. Prices are FOB Qingdao (EXW) and do not include freight, duty or installation.
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