Path-Q Solar

How long could a battery run my refrigerator and essential lights during an outage?

Answer

A rough estimate is usable battery energy divided by the average power consumed by the refrigerator and lights, adjusted for inverter losses and reserve limits. Actual duration depends on starting surges, cycling, ambient conditions, other connected loads, and whether solar can recharge the battery.

Key points

  • Use usable, not nameplate, battery capacity.
  • A refrigerator's running consumption is intermittent, but its compressor can require a higher starting surge.
  • Small loads such as internet equipment, controls, or standby devices can materially affect duration.

What it depends on

  • Battery usable energy and reserve setting
  • Inverter continuous and surge rating
  • Refrigerator duty cycle and startup demand
  • Lighting wattage and hours of use
  • Solar availability and backup architecture

Risks and trade-offs

  • A theoretical runtime can be overstated if it ignores conversion losses and reserve capacity.
  • Connecting additional appliances may shorten runtime substantially.
  • Solar panels may not recharge the battery during an outage unless the system is designed to operate in islanded mode.

Information you may need

  • Battery usable capacity and inverter ratings
  • Refrigerator energy label or measured consumption
  • Essential-light wattage and expected use
  • Backup circuit design and solar recharge capability

Your next step

What to do next

List the actual essential loads and ask the installer for a runtime calculation showing assumptions, reserve settings, startup capability, and solar-recharge conditions.

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SQ00507