Sizing a power station for a refrigerator

Step 1: the daily average, not the label

A full-size refrigerator averages 41 W (Running: ENERGY STAR Certified Residential Refrigerators dataset (US EPA open data), filtered to non-compact, non-built-in, 18-22 cu ft. 362 kWh/yr = 362,000 Wh / 8,760 h = 41.3 W average. Surge is from a manufacturer: Whirlpool Tech Sheet W11509412 Rev A (27 cu ft) lists 'Current locked rotor 11.3 A +/- 5%' on 115 VAC parts, so 11.3 A x 115 V = 1,299.5 W, rounded to 1,300 W (https://www.whirlpool.com/content/dam/global/documents/202103/tech-sheet-w11509412-reva.pdf). That same Whirlpool sheet independently cross-checks the average: 'Average Total Wattage' of 90-110 W while the compressor runs, x 45% run time at 70F ambient, is about 45 W, close to the 41.3 W derived from kWh/yr.). Its compressor runs perhaps a third of the day, so the label's running draw overstates the energy by three or more. A day is therefore 991 Wh of device energy; ÷ 0.85 for the inverter and × 1.2 headroom gives 1,400 Wh.

Your own fridge's figure is on its yellow EnergyGuide label: kWh per year × 1,000 ÷ 8,760 = average watts. A large side-by-side with an ice maker can average twice the ENERGY STAR figure; a small apartment fridge, half. Warm kitchens and frequent door-opening push it up; that is what the 20% headroom is for.

Step 2: the surge check, which decides more than capacity

When the compressor starts it draws roughly 1,300 W for a fraction of a second. A unit whose surge rating is below that trips its protection at the first start, however many watt-hours it holds. Of the 56 current units, 44 have a surge (or continuous, where no surge is stated) rating at or above 1,300 W and 12 do not. The units that fail the surge check (4Patriots Patriot Power Sidekick Solar Generator, BLUETTI Elite 100 mini, BLUETTI Elite 30 V2, DJI Power 500, EcoFlow RIVER 3 Plus, Goal Zero Yeti 300 and others) are compact units meant for devices, not appliances.

Step 3: days

Once the surge clears, days are the only variable: each day is the same 1,167 Wh after losses, so two days need twice the capacity and three days three times. Solar changes this only as much as the unit's maximum solar input allows; the solar pagehas the hours-of-sun arithmetic. Expandable units let you buy one day now and add a battery later.

Portable 12 V fridges are a different sum

A 12 V compressor cooler draws a fraction of a household refrigerator and runs from the unit's 12 V socket, skipping the inverter; use your cooler's label figure in the calculator.

Running it through an outage

A refrigerator keeps food safe for hours with the door shut, so the unit does not have to run it continuously: many people run it a few hours on, a few off, and stretch a day's capacity to two. The UPS switchover column matters if the unit sits between the wall and the fridge permanently; units that state 10 to 30 ms hand over without the fridge noticing. Thehome backup page adds the router, lights and phones to this load and checks the whole kit.