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🔋 Solar backup power

What Can a Solar Generator Power?

The answer depends on two numbers: the battery's capacity (how much energy it stores, in watt-hours) and its continuous AC output rating (how much power it can deliver at once, in watts). Here's exactly how long five common battery sizes — from 300Wh up to 3,600Wh — run 18 common devices, including whether each one can run a window AC unit.

Updated July 2026·7 min read·Affiliate disclosure

The two numbers that matter

Capacity (Wh) tells you how long you can run a load — a 1,000Wh battery holds roughly enough energy to run a 100W device for 10 hours (minus some loss to the inverter). Continuous AC output (W) tells you what you can run at all — a unit rated for 300W continuous output simply can't start a 1,200W space heater, no matter how much energy is left in the battery.

The charts below assume 85% efficiency (typical loss through the inverter and cabling) and use five reference tiers that match popular Jackery and EcoFlow units: a 300Wh/300W entry unit, a 1,000Wh/800W mid-size unit, EcoFlow's 1,024Wh/1,800W DELTA 2, a 2,000Wh/2,200W large unit, and EcoFlow's 3,600Wh/3,600W DELTA Pro. A dash (—) means that tier's output rating can't support that device at all; ❄️ next to a tier marks one with enough continuous output to run a small window AC unit.

Communication

Device300Wh (300W)1,000Wh (800W)1,024Wh (1,800W)2,000Wh (2,200W)3,600Wh (3,600W)
📱Smartphone (per charge)(15W)~16×~56×~58×~115×~204×
📶WiFi router + modem(10W)~24h~85h~87h~175h~305h
💻Laptop (per charge)(60W)~4×~14×~14×~28×~51×

Lighting

Device300Wh (300W)1,000Wh (800W)1,024Wh (1,800W)2,000Wh (2,200W)3,600Wh (3,600W)
🏮LED lantern(5W)~49h~170h~175h~345h~610h
✨String lights (20ft)(20W)~12h~43h~44h~87h~155h

Kitchen

Device300Wh (300W)1,000Wh (800W)1,024Wh (1,800W)2,000Wh (2,200W)3,600Wh (3,600W)
🧊Mini fridge(60W)~4.1h~14h~15h~29h~51h
🍽️Full-size fridge (avg draw)(150W)~1.6h~5.7h~5.8h~12h~20h
☕Coffee maker (brewing)(800W)—~1.1h~1.1h~2.2h~3.8h
⏱️Microwave(1000W)——~0.9h~1.7h~3.1h

Medical

Device300Wh (300W)1,000Wh (800W)1,024Wh (1,800W)2,000Wh (2,200W)3,600Wh (3,600W)
😴CPAP machine(40W)~6.1h~21h~22h~43h~77h
💊Nebulizer(100W)~2.4h~8.5h~8.7h~17h~31h

Comfort

Device300Wh (300W)1,000Wh (800W)1,024Wh (1,800W)❄️ Runs a window AC2,000Wh (2,200W)❄️ Runs a window AC3,600Wh (3,600W)❄️ Runs a window AC
🌀Box fan(45W)~5.4h~19h~19h~39h~68h
📺43" LED TV(65W)~3.8h~13h~13h~27h~47h
🔥Space heater(1500W)——~0.6h~1.2h~2.0h
❄️Window AC unit (small, 5–8k BTU)(900W)——~1.0h~1.9h~3.4h
❄️Window AC unit (large, 10–12k BTU)(1500W)——~0.6h~1.2h~2.0h

Tools

Device300Wh (300W)1,000Wh (800W)1,024Wh (1,800W)2,000Wh (2,200W)3,600Wh (3,600W)
🪚Circular saw (running)(1200W)——~0.7h~1.4h~2.5h
💧Sump pump (running)(800W)—~1.1h~1.1h~2.2h~3.8h

How to estimate your own device

Check the label or spec sheet on your device for its wattage (watts = volts × amps if only amps are listed). Then:

  1. 1Multiply the battery's rated Wh by ~0.85 to account for inverter loss — that's your usable energy.
  2. 2Divide usable Wh by the device's running watts to get hours of runtime.
  3. 3Confirm the device's watts is below the unit's continuous AC output rating, not just its capacity.
  4. 4For devices with a motor or compressor (fridges, ACs, pumps), expect a brief startup surge 2–3x higher than running watts — check the unit's surge rating too.

Sources

Recharging with solar

Pair any of these tiers with a 100–200W panel and expect a full recharge in 4–20+ hours of direct sun, depending on battery size. See our full solar backup power guide for recommended battery + panel kits, legal notes for states without a plug-in solar law, and setup steps.

Further reading