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Bess Rental Dubai

BESS
sizing guide.

How to size a battery energy storage system for your specific UAE project. The two numbers that matter (kW and kWh), how to calculate them from your equipment list, and worked examples for common project types.

At a glance
Read time10 minutes
NumberskW + kWh
ExamplesWorked

The two numbers

Every BESS is described by two numbers. Get these right and you get the right unit. Get them wrong and you'll either pay too much for an oversized unit or run out of power mid-shift.

1. Output power (kW)

This is the maximum instantaneous power the battery can deliver. Think of it as the "size of the pipe" — how much power can flow out at once. If your equipment draws 30 kW peak, you need a battery rated for at least 30 kW output (with some headroom).

2. Energy capacity (kWh)

This is how much total energy the battery stores. Think of it as the "size of the tank" — how long you can run before recharging. Capacity ÷ average load = runtime in hours. A 100 kWh battery powering a 10 kW load runs for 10 hours.

How to calculate your needs

Step 1: List your equipment

Make a list of everything that will be plugged in. For each, note rated power (in kW or W), whether it runs continuously or intermittently, and hours per day in use.

Step 2: Calculate peak power (kW needed)

Add up the rated power of everything that could be running simultaneously at the same moment. This is your peak. Add 25% headroom for surge currents (motors, lighting fixtures starting up).

Step 3: Calculate energy use (kWh needed)

For each piece of equipment, multiply rated power × hours of use per day. Add them all up. That's your daily kWh need. Round up by 20% for safety margin.

Worked example: medium wedding, 200 guests

  • Stage lighting: 8 kW × 6 hours = 48 kWh
  • Sound system: 3 kW × 6 hours = 18 kWh
  • AV / projector: 2 kW × 4 hours = 8 kWh
  • Catering hot boxes: 6 kW × 3 hours = 18 kWh
  • Decorative lighting: 4 kW × 6 hours = 24 kWh
  • Peak power: 8+3+2+6+4 = 23 kW (+25% headroom = 29 kW)
  • Daily energy: 48+18+8+18+24 = 116 kWh (+20% margin = 139 kWh)

Recommended: trailer 100–150 kWh unit with 30+ kW output.

Common sizing mistakes

  • Forgetting peak surge — motors and AC compressors draw 2–7× their rated power at startup
  • Confusing kW with kWh — both numbers matter
  • Ignoring recharge time — if you need to recharge during the project, factor in charge time
  • Sizing for 100% rather than 80% — batteries last longer when not regularly drained to 0%

When in doubt — call us

Send us your equipment list. We size for free in under an hour. We'd rather size correctly the first time than have you stuck on-site with the wrong unit.

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