How this calculator works
A power station's size is its battery capacity in watt-hours (Wh), and its output in watts (W). Capacity decides how long it runs, and output decides what it can run at the same time.
We allow 15% for inverter and battery losses, which is why you buy more than you use. The 0.75 for solar covers real-world losses in the panels, the cabling and the charge controller.
Worked example: a refrigerator (60 W for 24 h), router (15 W for 24 h), lights (50 W for 5 h), phones (15 W for 3 h) and a laptop (60 W for 4 h) use 1,440 + 360 + 250 + 45 + 240 = 2,335 Wh a day. With losses that is 2,747 Wh, so look at a 3,000 Wh unit. Four 200 W panels would refill it in about 4 sun hours.
Tips before you buy
- Add up what you actually must run in an outage. The fridge, router, phones and some lights are often a lot less than people expect, and heating and cooking appliances are what blow the budget.
- Check the output rating. A unit with 2,000 Wh of battery but only a 300 W inverter cannot run a 700 W refrigerator compressor.
- LiFePO4 batteries last far longer (about 3,000 cycles or more) than older lithium-ion packs (500 to 800 cycles), which matters if you plan to use it often.
- Solar input rates differ a lot between units. A 1,000 Wh station with 200 W of input takes five or more hours of full sun to recharge.
- Keep the unit charged to the level the maker advises in storage, and use it at least every few months.
Tools & materials for this project
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Frequently asked questions
What size portable power station do I need?
Add up the watt-hours you use per day (watts × hours for each device), divide by 0.85, and choose the next size up. A fridge, router and a few small devices usually needs 1,500 to 3,000 Wh for a day.
What is the difference between Wh and W?
Watt-hours (Wh) are the battery capacity, like the size of a fuel tank. Watts (W) are how fast power can be delivered, like how hard you can press the pedal.
How many solar panels do I need to recharge a power station?
Divide the daily watt-hours by (peak sun hours × 0.75) to find the panel watts, then divide by the size of each panel. A 2,000 Wh daily use at 4 sun hours needs about 670 W of panels.
Can a power station run a refrigerator?
Yes, if its output is at least about 700 W with surge capability, and its capacity covers the fridge's roughly 1,000 to 2,000 Wh a day. A mini fridge needs much less.
Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.