Scenarios › Power station for partial-home backup (essentials circuit)
What size power station for partial-home backup?
The essentials circuit: fridge, sump pump, furnace blower, lights, and internet — the loads a transfer switch usually feeds. The furnace blower’s startup surge dominates the inverter requirement. Here is the size that carries an essentials panel through a multi-hour outage, with expandable picks for longer.
6,516 Whcapacity needed
1,870 Wrunning watts
3,420 Wsurge to clear
8.0 hruntime horizon
This load: Refrigerator (modern) · Sump Pump (1/3 HP) · Gas Furnace Blower (1/2 HP) · LED Lights (10 bulbs) · WiFi Router + Modem. Want to tweak it? Open the full sizing tool and adjust the appliances and hours.
What size you need
This is a big load — about 6,516 Wh over 8.0 h. No single portable battery holds that much, but the expandable systems below meet the power draw (1,870 W running, 3,420 W surge) — add a battery module to reach the full watt-hours. This is the expandable-system territory most partial- and whole-home backup lives in.
The math
Running watts (everything on at once) = 1,870 W
Surge watts (worst single startup + the rest running) = 3,420 W
Average draw (cyclic loads counted by their duty cycle) = 733 W
Watt-hours = 733 W × 8.0 h ÷ 90% usable reserve = 6,516 Wh
1
EcoFlow DELTA Pro 3best expandable match
4,096 Wh 4,000 W cont · 8,000 W surge expandable ~5.0 h on this load $$$
A 4 kWh, 4,000 W (120/240 V) system built specifically for whole-home backup.
LiFePO4 · AC/solar/EV; expandable to 48 kWh · 113 lb
2
Goal Zero Yeti PRO 4000
3,993 Wh 3,600 W cont · 7,200 W surge expandable ~4.9 h on this load $$$
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
3
Anker SOLIX F3800
3,840 Wh 6,000 W cont · 9,000 W surge expandable ~4.7 h on this load $$$
A 6,000 W, 240 V system for whole-home backup including a well pump and electric range, expandable to ~27 kWh.
LiFePO4 · 120/240 V; expandable to 26.9 kWh · 132 lb
4
EcoFlow DELTA Pro
3,600 Wh 3,600 W cont · 7,200 W surge expandable ~4.4 h on this load $$$
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
5
Bluetti AC300 + B300
3,072 Wh 3,000 W cont · 6,000 W surge expandable ~3.8 h on this load $$$
A modular 3 kW system with a sub-20 ms UPS switch — toward whole-home with a transfer switch.
LiFePO4 · Modular; expandable to 12.3 kWh, 24/7 UPS · 116 lb
6
Goal Zero Yeti 3000X
3,032 Wh 2,000 W cont · 3,500 W surge expandable ~3.7 h on this load $$$
Three kWh on wheels for multi-day essentials backup.
NMC · AC/solar; integrates with home kit · 70 lb
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Disclosure.
The load, appliance by appliance
| Appliance | Running | Surge | Duty | |
|---|
| Refrigerator (modern) | 150 W | 1,200 W | 35% | size on its own → |
| Sump Pump (1/3 HP) | 800 W | 1,500 W | 20% | size on its own → |
| Gas Furnace Blower (1/2 HP) | 800 W | 2,350 W | 50% | size on its own → |
| LED Lights (10 bulbs) | 100 W | — | 100% | |
| WiFi Router + Modem | 20 W | — | 100% | |
⚡ 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
What size power station for partial-home backup?
For Refrigerator (modern), Sump Pump (1/3 HP), Gas Furnace Blower (1/2 HP), LED Lights (10 bulbs), WiFi Router + Modem over 8.0 h you need about 6,516 Wh — more than a single portable battery holds. Use an expandable system that meets the 3,420 W surge (like the EcoFlow DELTA Pro 3) and add a battery module to reach the full capacity.
How many watt-hours does this load need?
About 6,516 Wh for 8.0 h — we take the duty-weighted average draw (733 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 1,870 W; surge is 3,420 W.
Other scenarios
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.