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How to size a portable power station

Watts, watt-hours and run times: working out what a power station will actually run.

12 guides

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Sizing comes down to two numbers: watt-hours, which set how long a unit runs, and watts, which set what it can run at once. What size solar generator you need walks through the method with a worked outage day: list the loads, multiply watts by hours, then divide by about 0.85 for inverter losses.

If you already have a size in mind, the run-time guides check it against real appliances. What a 1000Wh power station can run covers a fridge, CPAP, router, lights and heaters on the most popular size. What a 3000 watt solar generator will run covers the 3 kWh to 5 kWh class and 240 V output. What size solar generator runs a refrigerator uses ENERGY STAR data for fridges and freezers, startup surge and panel counts.

Capacity is only half of an outage plan; the other half is refilling it. How to charge a solar generator compares wall, solar and car charging times from the makers’ own pages.

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01

What Size Solar Generator Do I Need? A Worked Sizing Method

Size a solar generator (portable power station) in watt-hours: list your loads, multiply watts by hours, allow for inverter losses, then check output and surge.

Sizing
02

Can Solar Power an Air Conditioner? Panels, Batteries, Mini Splits

Can solar panels or a battery run an air conditioner? Running and startup watts for window, portable, mini split and central AC, and the solar setup each needs.

Sizing
03

Cost to Install Solar Panels: Price per Watt and What Drives It

Installed home solar cost per watt in Berkeley Lab's 2025 data, why cash and loan prices differ, and how size, soft costs and incentives shape the bill.

Sizing
04

How Many Solar Panels Does It Take to Run a House?

Work out how many solar panels your house needs from your yearly kWh, local sun and panel wattage, with EIA usage figures and DOE production benchmarks.

Sizing
05

Solar Panels for Solar Generators: How to Match Your Power Station

Which portable solar panel works with your solar generator: match the voltage range, the solar input watts and the connector, and wire panels safely.

Sizing
06

What Can a 12V 100Ah LiFePO4 Battery Run? Runtimes Worked Out

A 12V 100Ah LiFePO4 battery stores about 1,280 Wh. See worked runtimes for a fridge, CPAP, lights and router, its 100 A limit and cold-weather charging rules.

Sizing
07

What Size Off-Grid Inverter Does a Solar System Need?

Size an off-grid solar inverter from your loads: continuous watts plus a margin, surge for motors and pumps, battery voltage, and split-phase 240V needs.

Sizing
08

What Size RV Solar Panel Kit Do You Need? Sizing and Kit Contents

How to size an RV solar panel kit from your daily watt-hours and sun hours, what a kit includes, and when flexible panels beat rigid ones on a camper roof.

Sizing
09

How to Charge a Solar Generator: Wall, Solar and Car Times

How fast a solar generator (portable power station) charges from a wall outlet, solar panels or a car, with each maker's listed times and solar input limits.

Sizing
10

What Size Solar Generator Runs a Refrigerator and Freezer?

Size a solar generator for a fridge and freezer using ENERGY STAR data: daily watt-hours, startup surge, run times and how many solar panels it takes.

Sizing
11

What Will a 3000 Watt Solar Generator Run? 3000W to 5000W Sizing

What a 3000W, 4000W or 5000W solar generator can run and for how long: watts vs watt-hours, fridge run times from ENERGY STAR data, and the Jackery 3000.

Sizing
12

What Can a 1000Wh Solar Generator Run? Runtimes for Common Appliances

Runtimes on a 1000Wh solar generator (portable power station) for a fridge, CPAP, router, LED lights, space heater and microwave, with the math shown.

Sizing

Frequently asked questions

How do I work out what size solar generator I need?

Multiply each appliance's watts by its hours of use, add the results, then divide by about 0.85 for inverter losses. EcoFlow's runtime guide suggests multiplying capacity by 0.80 to 0.90 for AC loads, and 0.85 sits in the middle.

How long will a 1000Wh solar generator run a fridge?

About 16 hours for a median full-size ENERGY STAR refrigerator, using about 850 usable watt-hours. Your own fridge may use more or less, so run it on the unit for a few hours before storm season.

What is the difference between watts and watt-hours?

Watts are the rate of power an appliance draws or a unit can deliver at once. Watt-hours are stored energy: watts multiplied by hours. Capacity in watt-hours sets runtime, and rated output in watts sets what can run at all.

Sources

  1. Test Your Power Station Runtime Before an EmergencyEcoFlow
  2. ENERGY STAR Certified Residential Refrigerators (dataset)U.S. EPA ENERGY STAR
  3. Watt Does It Cost to Use It?U.S. Department of Energy

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