Inverter/UPS Capacity for AC Calculator

Calculate the inverter or UPS capacity needed to run your AC during power outages.

Advertisement

Ad Space

Slot: 7338695895

AC & Location Details

Enter your AC and solar conditions

Ton
W
hrs
W
hrs

Solar System Required

To power your AC with solar

Inverter Sizing for AC

Running AC on inverter requires careful sizing to handle high startup current and continuous operation. Undersized inverters will trip or fail when the AC compressor starts.

AC Power Requirements

ACs have two power demands to consider:

  • Running watts: Continuous power during operation
  • Startup surge: 2-5x running watts for first few seconds
  • Example 1.5 ton: 1,500W running, 4,500W surge

Inverter Sizing by AC Size

Minimum inverter capacity (with safety margin):

  • 0.75 ton: 1.5-2 kVA inverter
  • 1.0 ton: 2-2.5 kVA inverter
  • 1.5 ton: 3-4 kVA inverter
  • 2.0 ton: 4-5 kVA inverter

Inverter AC Advantage

Inverter ACs are much easier to run on battery backup:

  • Soft start: No massive startup surge
  • Lower running watts: Variable speed reduces consumption
  • Smaller inverter needed: 1.5 ton inverter AC may run on 2.5 kVA
  • Longer battery life: Lower consistent draw

Battery Sizing

Battery capacity determines backup duration:

  • Formula: Battery Ah = (Watts × Hours) ÷ (Voltage × Efficiency)
  • Example: 1,500W for 2 hours = (1,500 × 2) ÷ (24V × 0.8) = 156 Ah at 24V
  • Practical: 4 × 150Ah batteries at 24V for ~2 hours of 1.5 ton AC

System Components

  • Inverter: Pure sine wave essential for AC motors
  • Batteries: Deep cycle or lithium for frequent discharge
  • Charger: High-capacity for quick recharge
  • Wiring: Heavy gauge for high current
  • Transfer switch: Automatic switchover from grid

Cost Considerations

  • 3-4 kVA inverter: $400-800
  • Battery bank (24V, 300Ah): $600-1,200 (lead-acid) or $2,000+ (lithium)
  • Installation: $200-500
  • Total for 2-hour backup: $1,200-2,500+

Alternatives to Consider

  • Generator: More runtime, lower upfront cost
  • Solar + battery: Long-term savings, daytime use
  • Smaller AC: Reduce backup requirements
  • Accept limited backup: Fans + essential loads only

Frequently Asked Questions

Can inverter run AC?▼

Yes, but you need adequate capacity. A 1.5 ton AC typically needs a 3-4 kVA inverter with sufficient battery backup.

What size inverter for 1.5 ton AC?▼

A 1.5 ton AC needs minimum 2.5-3 kVA inverter capacity to handle startup surge. Consider 4 kVA for safety margin.