Battery Energy Storage for Factories and Manufacturing Plants

Where Your Money Actually Leaks

Your bill has two main components: energy (UAH/kWh) and capacity (UAH/kW). For many factories, the capacity charge—based on your highest 30-minute average demand in a month—can be 20–30% of the total. That peak often comes from a single motor starting: a 500 kW motor can draw 6–8 times its rated current for a few seconds, spiking your demand and setting your contracted capacity for the whole year.

The second leak is downtime. When a voltage sag dips below 80% of nominal, even for 100 ms, PLCs and VFDs trip. A single line stop can cost thousands of dollars in lost production and cleanup. You often don't see this on a bill—it's a hidden cost that's much larger than the capacity charge.

Storage attacks both: it shaves the peak that sets your demand charge, and it bridges the inrush with real power, holding voltage up.

The Physics: Why Your Plant's Problem Is Unique

Unlike a commercial building, a factory has inductive loads. Motors, transformers, and welders draw reactive power and have high inrush currents. When a large motor starts, it draws a magnetizing current that can be 6–8 times full load for a few cycles. This causes a voltage drop across the grid impedance—at 0.4 kV, a 500 kW motor can drop bus voltage by 10–20% if the transformer is undersized.

A BESS responds in milliseconds. It can supply real power (and optionally reactive power with a 4-quadrant inverter) to support voltage during the sag. But it must be sized not just for energy, but for peak power and response time. A battery that is too small will saturate and do nothing. A battery too large is wasted capital.

Rough Sizing: Power and Capacity for a 200–1500 kW Plant

Power: For peak shaving, size the BESS power to cover the difference between your highest 30-minute demand and your target contracted capacity. For example, if your max demand is 1200 kW and you want to cut to 1000 kW, you need at least 200 kW of BESS power.

Capacity: For a typical 1–2 hour peak window, choose capacity in kWh equal to power × 1.5–2 hours. A 200 kW/400 kWh system is a common starting point.

For voltage support: Size for the largest motor's inrush: roughly 3–5 times its rated power for 1 second. A 500 kW motor may need 1500–2500 kW of instantaneous power, but only for a second. That requires a battery with high C-rate (2C or more) and a large inverter, but not necessarily large energy.

This is rough without a load profile. A proper design uses your actual 15-minute interval data.

What Happens If You Size It Wrong

Undersized power: The BESS cannot shave the peak completely, so you still pay the higher demand charge. It may also overheat if you try to push it. For voltage support, if the battery cannot deliver the inrush current, the sag remains and your line trips.

Undersized energy: The battery depletes before the peak window ends. You get a partial shave, but then you face a second peak as the battery dies.

Oversized: You spend extra capital that pays back slower. You may also violate grid connection agreements if you export power unintentionally.

The only safe way is to model the system with your actual load data.

What an Engineer Needs From You

• 12 months of 15-minute interval load data (from your energy meter or utility). This shows your true peaks and duration.
• Copies of your electricity bills for 12 months—both energy and capacity components.
• A single-line diagram of your low and medium voltage system, including transformer ratings, cable sizes, and motor loads.
• Details on your largest motors: rated power, starting method (DOL, VFD, soft starter), and frequency of starts.

Without these, any sizing is a guess. With them, we can simulate in MATLAB/Simulink and give you a bankable payback figure.