Quick answer: add up the running watts of everything you will use at once to size the inverter. Then multiply each device's watts by its hours per day to size the battery in watt-hours. Most households land at about 1,000Wh with a 1,500W inverter and a 200W panel. Check what you'll run below.
What size power station do I need?
| Use | Appliance | Watts | Hours/day |
|---|
How to size a power station
A power station has two ratings that answer two different questions. Watts are the inverter's ceiling: what you can run at the same moment. Watt-hours are the tank: how long you can run it. The calculator adds 20% headroom to the inverter, adds 15% to the battery for inverter losses, and adds the startup surge of motors like fridge compressors and pumps. Our Solar Generators 101 explainer covers each rating in depth.
| Use case | Battery | Inverter |
|---|---|---|
| Weekend of phones, lights, laptop | 300–500Wh | 300–600W |
| Outage essentials with a fridge | 1,000Wh | 1,500W |
| Multi-day backup, fridge + CPAP + freezer | 2,000–3,000Wh | 2,000–2,400W |
| Whole-room AC, well pump, tools | 3,000Wh+ expandable | 3,000W+ |
Frequently Asked Questions
What size power station do I need to run a refrigerator?
A full-size fridge runs at about 150W but surges to 450W or more when the compressor starts, and uses roughly 1,000 to 1,500Wh a day. A 1,000Wh station with a 1,500W inverter runs one for most of a day; plan on 2,000Wh for a full 24 hours.
How long will a 1,000Wh power station last?
Divide its capacity, minus about 15% for inverter losses, by your load. A 1,000Wh station runs a 100W load for about 8.5 hours, a 40W CPAP for roughly 21 hours, or charges a phone about 50 times.
How many solar panels do I need to recharge a power station?
Divide the watt-hours you use per day by your peak sun hours, then by 0.7 for real-world losses. Refilling 1,000Wh at 4.5 sun hours takes about 320W of panels, so three or four 100W panels.
What is the difference between watts and watt-hours?
Watts measure how much power a device draws or a station can deliver at once. Watt-hours measure stored energy: watts multiplied by hours of use. A 100W TV running for 3 hours uses 300Wh.
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