Off-Grid Solar Calculators

Appliance-specific

12V Compressor Fridge vs Residential 110V Fridge

A 12 V compressor fridge often averages 400–600 Wh/day. A household 110 V fridge plus inverter losses can be two to four times that, even if the kitchen unit looks efficient on the Energy Guide label.

Inputs

Units
W

Fraction of the day the compressor actually runs.

W
h

Terms of Service

Results

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Engineering methodology

12 V daily watt-hours = DC running watts × duty cycle × 24 hours. 110 V daily watt-hours = (AC running watts × compressor hours) ÷ inverter efficiency. Saved watt-hours = AC path minus DC path (can be negative if the household unit is tiny). Duty cycle is the fraction of the day the 12 V compressor actually runs. Inverter idle draw is not included.

Frequently asked questions

How many watt-hours per day does a 12 V compressor fridge use?

A typical van compressor fridge might run 40–50 W at 30–55% duty cycle: 45 W × 0.40 × 24 h ≈ 432 Wh/day at the typical 40%. Hot ambient and door openings raise duty cycle.

Why does a household fridge cost more energy on an inverter?

You pay running watts × hours and then divide by inverter efficiency (often 80–90%). A 150 W kitchen fridge for 8 compressor hours through 85% efficiency is about 1,412 Wh—often two to four times a 12 V compressor box.

Is duty cycle the same as Energy Guide kWh/year?

No. Energy Guide is an annual laboratory cycle. This tool needs running watts and either a duty cycle (12 V) or compressor hours (AC). Measure both with a plug meter and a DC shunt when you can.

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