Power stationsSections
What size power station do you need?
Start from your devices, not from watts you don't know. We do the honest math — real usable capacity, startup surge, solar recharge reality — and answer with the stations whose sourced specs actually cover it.
1 · What are you preparing for?
- Devices need (per day)
- 9,600Wh
- Running load
- 800W
- Startup surge peak
- 2000W
A 12,000Wh-class station covers your 1-day need — startup surge, not running watts, is what rules out smaller units here.
- You need (battery side)
- 11,294Wh battery-side
- Running load
- 800W
- Startup surge peak
- 2000W
How we got there
| Device | Avg draw | Over 1 day |
|---|---|---|
| Sump pump (1/3 HP) | 800W | 9,600Wh |
| Devices total | 9,600Wh |
On top of the device total, each station is charged its real conversion losses — AC loads ÷ inverter efficiency (0.85 typical, by chemistry), DC loads ÷ 0.9 — and capacity is counted from the best number we have for that unit: lab-measured usable, else the manufacturer's usable figure, else rated × 0.9 depth-of-discharge. No vague “reserve” padding — every derate is named in the methodology.
Lowest-capacity passing pick in our target margin band; otherwise the smallest passing unit.
- Runs your kit
- 1.1 days
- AC delivered (est.)
10,445 Whest.. Show source
estimated sourceus.ecoflow.com2026-07-04 · AC estimate from sourced battery capacity and the published efficiency assumptionhttps://us.ecoflow.com/products/delta-pro-ultra-x- Weight
135.5 kg. Show source
claimed sourceus.ecoflow.com2026-07-04https://us.ecoflow.com/products/delta-pro-ultra-x
- capacity covers the plan
- continuous output covers the running load
- surge unverified — no sourced spec
☀️ With your panels this still loses 10174Wh/day — dead in ~1.2 days. Indefinite runtime needs ~4050W of panels.
Scenario: Custom kit — 1 days Duration: 1-day Energy need (battery side): 11,294Wh usable Running load: 800W Peak startup surge: 2000W Recommended minimum: 12,000Wh class, Why: startup surge, not running watts, is what rules out smaller units here.
Real examples
Can a 1,000Wh power station run a refrigerator through a 2-day outage?
This 2-day refrigerator plan needs 3,024 Wh delivered to the appliance, before station losses. Its sourced startup requirement is 1,200 W. Measure your fridge's daily energy to replace this example's duty-cycle assumption.
- Refrigerator (full-size) · 2026-07-06
How big a battery do 3 nights of CPAP need?
The configured humidifier-off preset uses 72 Wh per night, or 216 Wh over 3 nights, before station losses. Check your machine's supported converter and prescribed settings; this example does not establish compatibility for other models.
- CPAP (humidifier off) · 2026-07-06
What runs a weekend camp with a 12V fridge and Starlink?
This plan uses 2,164 Wh per day for the camping fridge, Starlink Standard and phone charging. Starlink runs for the full day here; Mini requires a different input. Open the plan to change hours and inspect the configured panel's solar balance.
- 12V camping fridge (45L) · 2026-07-06
- Starlink (Standard kit) · 2026-07-06
- Phone (one full charge) · 2026-07-06
How the math works
Every constant is published — same numbers as our scoring methodology, no house secrets:
- Device energy: nameplate watts × duty cycle (compressors cycle; a fridge's average is far below its label) × hours × days. Your watt-meter measurement overrides ours.
- Capacity truth: lab-measured usable Wh when we have it → manufacturer usable figure → rated × 0.9 depth-of-discharge default. Never double-derated.
- Conversion losses: AC loads ÷ 0.85 inverter efficiency (chemistry-specific where known); DC loads ÷ 0.9.
- Surge check: largest single startup surge + everything else still running, vs the station's sourced surge rating. No sourced rating → flagged “unverified”, never guessed.
- Solar reality: harvest = min(your panels, station's max input) × 4 peak-sun hours × 0.7 real-world derate.
- Right-size pick: smallest passing station with 15–30% capacity headroom — we don't oversell, and a station only appears when it actually clears the load you entered.
Sizing questions, straight answers
Watts vs watt-hours — what's the difference?
Watts (W) are a rate — how hard your devices pull right now. Watt-hours (Wh) are a quantity — how much energy the battery holds. A 300W load drains 300Wh every hour. You need both: enough watts (inverter) to run everything at once, and enough watt-hours (capacity) to run it for as long as you need.
Why do you count less than the rated capacity?
No station delivers its label. The battery holds back a protection reserve, and the inverter loses ~15% turning DC into AC. Where a unit has been lab-measured we use that number; otherwise the manufacturer's usable figure; otherwise rated × 0.9 — and then AC loads still pay the inverter toll. That's why a "1,000Wh" unit realistically serves ~765Wh of AC.
What are starting (surge) watts and why do they matter?
Motors and compressors briefly pull 2–6× their running watts at startup. A fridge that runs at 180W can spike past 1,000W for a moment — and if the station's surge rating can't clear it, the unit trips even though the math "fit". We check the worst single-start moment against each station's sourced surge spec.
Can solar keep a power station running forever?
Only if daily harvest beats daily draw. We assume 4 peak-sun hours and real-world panel losses (×0.7), capped by what the station's charge controller physically accepts. The calculator tells you the panel wattage indefinite runtime actually requires — and flags when a station can't accept that much.