Battery Energy Storage for Hotels: Kill the Diesel, Cut the Peak

Where the money leaks in a hotel's electricity bill

Your bill has three parts: energy (UAH/kWh), capacity/demand (UAH/kW), and reactive power penalties. For a 200-room hotel, demand charges often exceed 30% of the bill. The peak that sets that charge is usually a 15-minute window in the evening—when guests return, use lifts, shower (hot water), and crank the AC. That single window defines your tariff for the whole month.

Diesel generators don't help here. They run only during outages. They don't smooth peaks, and they cost UAH 20–40 per hour in fuel plus maintenance. The grid still sees your evening spike. Storage, however, does both: it charges at night or midday when energy is cheap, then discharges during that 18:00–22:00 peak, shaving 100–200 kW and cutting your demand charge.

The physics of a hotel's load: why peaks are spiky

A hotel is not a factory. It has a base load—lighting, fridges, front desk—maybe 30–40% of peak. On top of that are sudden, high-power events: two lifts starting simultaneously (each 15–20 kW), a 500-L electric water heater kicking in (30 kW), or a chiller cycling. These spikes last seconds to minutes, but they add up and set the demand meter.

Voltage also matters. At 0.4 kV, a 300 kW battery requires a 630 kVA transformer. If you have a 400 kVA transformer, you are limited to 250 kW. We always check the transformer before promising anything.

Sizing method: power and capacity for 60–300 kW

Power is straightforward: it equals the evening peak you want to shave. Measure your 15-minute peaks from the last 12 months. Suppose your peak is 250 kW, and you want to cut it to 180 kW—that's a 70 kW battery. Capacity is then based on how long you need to hold that discharge. For a 2-hour evening window, you need 70 kW × 2 h = 140 kWh usable. With a 90% depth of discharge, that's a 155 kWh battery—we round up to a standard 160 kWh cabinet.

For backup, you have a different calculation: how many kW of critical loads (lifts, lighting, water pumps, fire alarms) and for how long. A 100 kW load for 1 hour needs 100 kWh. If you want both peak shaving and backup, you size for the larger of the two and add a control system that prioritises.

Without a load profile, any figure is rough. We need at least a month of interval data (15-min or 30-min) to design properly.

What happens when you undersize or oversize

Undersized power: the battery hits its limit during the peak, and you still pay demand charges. The payback stretches from 4 years to 8. Undersized capacity: you shave the first hour, then the battery is empty and the second hour spikes—your demand charge resets. Oversized: you pay an extra UAH 10,000–15,000 per 100 kWh of battery that you rarely use. The inverter also costs more.

We have seen hotels oversize by 50% because a salesperson said 'bigger is better'. That is UAH 1.5 million wasted. The correct size is a technical decision, not a marketing one.

What our engineers need from you

To prepare a feasibility study, we request: (1) 12 months of electricity bills (all pages, including demand charges); (2) 15-minute or 30-minute load profile from your smart meter or substation—if you don't have it, we install loggers for 2 weeks; (3) single-line diagram of your low-voltage switchgear; (4) transformer nameplate; (5) generator details (if you have one) and its automatic transfer switch; (6) your tariff structure and whether you have day/night rates.

We take care of the rest: load analysis, battery sizing, energy savings calculations, and a payback model. We are an EPC contractor—we do the audit, design, supply, installation, commissioning, and service. LiFePO4 cells from CATL or other Tier-1, liquid cooling, BMS, EMS/SCADA, IP55/C4 outdoor cabinets. Not a residential system—those go to SolarProm.com.ua.