Scenarios › Power station for a home outage: fridge + CPAP + sump pump

Power station for a home outage (fridge + CPAP + sump pump)

The classic storm-night kit: keep the fridge cold, run a CPAP overnight, and keep the sump pump ready so the basement stays dry. The sump pump’s 1,500 W startup surge is what sets the minimum inverter — here is the unit that covers all three, with room to grow.

3,373 Whcapacity needed

990 Wrunning watts

2,040 Wsurge to clear

12 hruntime horizon

This load: Refrigerator (modern) · CPAP Machine (no humidifier) · Sump Pump (1/3 HP). Want to tweak it? Open the full sizing tool and adjust the appliances and hours.

What size you need

You need about 3,373 Wh — and 4 units fit. The smallest sufficient is the EcoFlow DELTA Pro; we never push more capacity than your load can use. Surge to clear: 2,040 W.

The math
Running watts (everything on at once) = 990 W
Surge watts (worst single startup + the rest running) = 2,040 W
Average draw (cyclic loads counted by their duty cycle) = 253 W
Watt-hours = 253 W × 12 h ÷ 90% usable reserve = 3,373 Wh

EcoFlow DELTA Prosmallest that fits

3,600 Wh 3,600 W cont · 7,200 W surge expandable ~13 h on this load $$$

The whole-home contender on wheels — 3,600 W, expandable to 25 kWh, panel-ready with a transfer switch.

LiFePO4 · AC + EV charging; expandable to 25 kWh · 99 lb

Check price at EcoFlow → Full specs

Anker SOLIX F3800

3,840 Wh 6,000 W cont · 9,000 W surge expandable ~14 h on this load $$$

A 6,000 W, 240 V system for whole-home backup including a well pump and electric range, expandable to ~27 kWh.

LiFePO4 · 120/240 V; expandable to 26.9 kWh · 132 lb

Check price at Anker SOLIX → Full specs

Goal Zero Yeti PRO 4000

3,993 Wh 3,600 W cont · 7,200 W surge expandable ~14 h on this load $$$

Goal Zero’s LiFePO4 flagship — 4 kWh, 3,600 W, whole-home with the transfer switch and tanks.

LiFePO4 · Fast AC; expandable to ~27 kWh · 104 lb

Check price at Goal Zero → Full specs

EcoFlow DELTA Pro 3

4,096 Wh 4,000 W cont · 8,000 W surge expandable ~15 h on this load $$$

A 4 kWh, 4,000 W (120/240 V) system built specifically for whole-home backup.

LiFePO4 · AC/solar/EV; expandable to 48 kWh · 113 lb

Check price at EcoFlow → Full specs

🔗 The "Check price" buttons are brand-direct affiliate links. Once our brand affiliate programs are approved these will earn a commission — at no extra cost to you, and it never changes which unit we recommend. Disclosure.

The load, appliance by appliance

Appliance	Running	Surge	Duty
Refrigerator (modern)	150 W	1,200 W	35%	size on its own →
CPAP Machine (no humidifier)	40 W	—	100%	size on its own →
Sump Pump (1/3 HP)	800 W	1,500 W	20%	size on its own →

⚡ Informational only — a computed sizing estimate from published appliance-wattage charts and manufacturer station specs. It is not an electrical guarantee. For hardwired or whole-home backup, transfer switches, or any permanent install, consult a licensed electrician. Appliance wattages are representative chart values and vary by model; check your nameplates. Duty cycle (how much of the time a load actually draws) is how we keep the watt-hour estimate from overselling capacity.

Common questions

Power station for a home outage (fridge + CPAP + sump pump)

For Refrigerator (modern), CPAP Machine (no humidifier), Sump Pump (1/3 HP) over 12 h, you need about 3,373 Wh of capacity, 990 W continuous output, and at least 2,040 W of surge. The smallest unit that clears all three is the EcoFlow DELTA Pro; a step-up like the next size adds headroom for longer outages.

How many watt-hours does this load need?

About 3,373 Wh for 12 h — we take the duty-weighted average draw (253 W, since cyclic loads like fridges and pumps don't run constantly), multiply by the hours, and divide by a usable-capacity reserve. Running watts are 990 W; surge is 2,040 W.

Other scenarios

What size power station runs a CPAP all night?

8.0 h

What size power station / battery backup for a sump pump?

6.0 h

What size power station / solar generator for van life?

12 h

What size power station runs a refrigerator in an outage?

24 h

What size power station runs a 1500 W space heater?

3.0 h

What size power station runs a window AC?

5.0 h

Sources: appliance wattages — standard appliance/generator sizing charts; station specs — manufacturer published specifications (compiled 2026-06-15; approximate). Informational only — a computed sizing estimate from published appliance-wattage charts and manufacturer station specs. It is not an electrical guarantee. For hardwired or whole-home backup, transfer switches, or any permanent install, consult a licensed electrician.