750 kW Battery Energy Storage System — Pre-Design Survey for Industrial Sites

First: Understand Power vs Capacity and C-Rate

For a 750 kW system, power (kW) is the rate of charge/discharge, while capacity (kWh) is the energy stored. The ratio (C-rate) = power / capacity. For this class, typical capacity is 1.5–3 MWh, giving C-rates from 0.25C to 0.5C. Choose C-rate based on the application: peak shaving with 1–2 hour discharge needs 0.5–1C, while time-shift with 4 hours needs 0.25C.

You must obtain a load profile (15-min interval, at least 1 year) to size capacity correctly. Without that, any capacity figure is rough. Also determine if you need black start or islanding – that changes the inverter and control requirements.

Which Documents to Pull Before Site Visit

Ask the client for: single-line diagram of the facility, transformer nameplate (kVA, impedance, tap changer), utility bills for last 12 months (demand and energy), and any existing power factor correction or harmonics study. Also get the grid connection agreement – it defines allowed export/import limits and any penalties.

Check the short-circuit level at the point of connection. If it's a weak grid, the BESS inverter may need special settings or a transformer. Also verify the available space and concrete foundation specs – a 750 kW system can be in a 10-ft container or in an indoor room with cabinets.

Grid Constraints to Verify

At 750 kW, typical connection is at 0.4 kV (low voltage) if the site has a large transformer (e.g., 1000 kVA) with spare capacity. For larger distances or if the transformer is small, a 10 kV medium voltage connection with a step-up transformer may be needed. At 0.4 kV, distances above 100 m cause excessive voltage drop – you will need a dedicated feeder or a transformer.

Check the utility's allowed reverse power flow. Some contracts forbid export or limit it to a small amount. Also verify the grid impedance – a BESS can cause voltage rise during charging; you may need a reactive power control or a line drop compensator. Without some of these checks, the system may not pass utility approval.

Footprint, Siting, and Enclosure Options

For 750 kW, you have three typical layouts. First, a 20-ft container (approx. 6 m x 2.4 m) with battery racks, PCS, and auxiliary transformer – all outdoor, IP55/C4 coating. Second, a row of outdoor cabinets (each about 2 m x 1 m x 1.5 m) – modular but requires more space and cable routing. Third, an indoor room with battery racks and separate power room – good for existing buildings with fire suppression.

Concrete foundation must be level and withstand dynamic loads – a 20-ft container with batteries can weigh 10–15 tonnes. For indoor, check floor load rating (min. 750 kg/m²) and ventilation. Also plan for cooling – liquid cooling is standard for this class, but you must have a heat rejection path.

CAPEX Range and What Moves It

For a 750 kW / 1.5–3 MWh system, CAPEX typically ranges from $300,000 to $550,000 (or roughly 12–20 million UAH) depending on capacity, integration complexity, and grid connection. The main cost drivers are battery cells (about 60% of cost), power electronics (15–20%), and balance of plant (civil works, transformer, cabling).

Capacity is the biggest lever – going from 1.5 to 3 MWh increases CAPEX by 70–80%. Also, voltage level matters: 10 kV connection adds a transformer and switchgear, adding 5–10%. Site conditions – indoor vs outdoor, distance to grid, and weatherproofing – affect civil costs. We give a firm quote only after a site audit and load profile analysis.