Battery Energy Storage for Shopping Malls & Retail

Input Data: What an Engineer Needs Before Sizing

Start with the load profile. Not a monthly bill, but a 15-minute interval record for at least one year. You need to see the daily peaks, the night troughs, and the seasonal variation. A mall in Kyiv will have a different profile than one in Odesa because of HVAC load.

Second, the single-line diagram. We must know the existing switchgear, the transformer rating, and whether you have a standby generator. The voltage class matters: at 0.4 kV you are limited to about 600 kW per feeder, so for larger malls we look at 10 kV connection.

Third, the tariff structure. In Ukraine, the difference between day and night tariffs can be 2-3 UAH/kWh, but that varies by region and supplier. We need your current contract to calculate arbitrage savings.

Finally, the critical loads list: which refrigeration units, POS systems, CCTV, and emergency lighting must stay on during an outage. That defines the backup power requirement.

Power and Capacity Sizing: A Rough Method

For power, take the maximum demand during a typical weekday. For a 10,000 m² mall, that might be 300 kW, but we always verify with the load profile. The BESS power rating should cover at least the critical loads, typically 20-30% of peak demand, plus a margin for starting currents of compressors.

For capacity, decide the autonomy time. For trading continuity, 1-2 hours is usually enough to ride through most outages or to perform an orderly shutdown. At night, the same battery can do a full charge cycle using cheap night tariff.

A rough formula: Capacity (kWh) = Critical Load (kW) × Autonomy (h) ÷ Depth of Discharge (0.9 for LiFePO4). For a 300 kW peak with 100 kW critical load and 2 hours, that's 100×2/0.9 ≈ 222 kWh. Round up to 250 kWh.

But that is a starting point. Without the load profile, the figure is rough. The final size also depends on the arbitrage window: if the night tariff lasts 8 hours, the charger power must be sufficient to fill the battery in that window.

Connection Topology: AC or DC Coupling?

Most malls operate at 0.4 kV, so we connect the BESS to the low-voltage busbar via a dedicated AC breaker. This is simple and allows the battery to support the entire facility. We use a bi-directional inverter that can island, so during an outage, the battery can supply selected circuits via a transfer switch.

For malls with a 10 kV incoming line, we might connect the BESS on the secondary side of the transformer, but that limits the power to the transformer rating. If you need to export to the grid, a 10 kV connection is better, but that requires a dedicated transformer and protection.

We always include a generator interlock if there is a diesel backup. The BESS can be the first response, and the generator can start later, but they must never run in parallel without proper synchronization.

What Goes Wrong If Sizing Is Wrong

Undersize the power, and you cannot start the refrigeration compressors. The inrush current is 3-5 times running current, so a 100 kW BESS might not start a 20 kW compressor. The result: breaker trips, and you lose the load anyway.

Undersize the capacity, and you run out of battery before the outage ends. For a 2-hour outage, if you only have 1 hour of storage, the freezers start to thaw, and you lose inventory. That is direct financial loss.

Oversizing is not as catastrophic but hurts the business case. You pay for capacity you never use, and payback stretches from 4 to 7 years. Also, if the battery is too large for the tariff spread, you cannot fully charge it during the night window, so the arbitrage revenue drops.

Another common mistake: ignoring the peak demand charges. If your tariff has a capacity charge, the BESS can shave peaks, but only if it is sized to the specific peak pattern. Otherwise, you leave money on the table.

Why BESS Ukraine Engineering Group?

We are a full-cycle EPC contractor: audit, design, supply, installation, commissioning, and service. We have done feasibility studies for industrial and commercial sites across Ukraine, and we know the grid codes and tariff structures.

We use LiFePO4 cells from CATL and other Tier-1 manufacturers, with liquid cooling and a BMS that balances the cells to within 2%. Our cabinets are IP55/C4 rated for outdoor installation, but we also build 20/40 ft container solutions for larger systems.

We do not do residential systems—that is our sister company SolarProm.com.ua. We focus on 50 kW to 5 MW industrial storage. Contact us at +380 44 339-50-20 or engineering@bess.com.ua for a site assessment.