Capacity: Think about how much electricity you would need in a blackout, and then study the power requirements of the device so you can get a good estimate of how many watt-hours a portable power station would need. If you only need to charge some phones and light them for a few hours with one or two LED bulbs, you probably won't need more than 150Wh portable power.

If you need power for multiple days or need to run larger appliances, you can even get portable power stations that provide 4000-5000WH. But these devices are expensive and often as big and heavy as gas-fired generators -- though these behemoths still have the advantage of running safely indoors. For these sites, the optimal location is in the 500-2000WH range; That's the beauty of the portable part, it has enough power to make a difference.

Ports: Most portable stations will offer plenty of output - USB ports, wireless charging, AC ports, DC ports, etc. Think about what you need to drive and make sure the model you choose provides it.

Size: Make sure you can easily power stations. If your house is bursting, measure it and balance the size of the unit, so you don't have to balance it on a toaster or something in the short time between emergencies.