Emergency Power Guide: Backup Power Options for Home Outages

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Quick answer: start by listing what you truly need to run during an outage and adding up the watts and watt-hours. For phones, lights, a radio and a CPAP, power banks and a portable power station usually cover it. For a refrigerator, a well pump or a furnace blower over several days, many households look at a fuel generator, used only outdoors and far from openings, or a larger battery system paired with solar panels. Whatever you choose, follow the safety rules from Ready.gov and the Consumer Product Safety Commission: never run a generator or grill indoors, never plug a generator into a wall outlet, and install battery-powered carbon monoxide alarms.

Power outages are one of the most common emergencies a household faces. Hurricanes, ice storms, heat waves, wildfires and equipment failures all knock out electricity, and the outage can last minutes or stretch into days. The question is rarely whether the power will go out but how ready the home is when it does.

This guide is the hub for every backup power article on Preparing in the City. It covers how to work out what you need, the main equipment choices, the safety rules that matter most, and how to keep food, medicine, light and communication going. Each section links to a deeper guide where one exists, and the related guides list at the end grows as new articles publish.

In this guide

Why Outages Happen and How Long They Last
What You Actually Need to Power: A Simple Watt Worksheet
Portable Power Stations
Gas, Propane and Dual-Fuel Generators
Solar Charging Basics
Safety: Carbon Monoxide, Fire and Fuel
Keeping Food Safe Without Power
Lighting, Radios and Phone Charging
Medical Device Backup Planning
Apartment-Friendly Options and a Starter Checklist
Frequently Asked Questions
Related Guides

Why Outages Happen and How Long They Last

Most long outages trace back to weather. High winds bring down trees and lines, ice coats wires until they snap, flooding damages substations and heat waves push demand past what the grid can carry. The U.S. Energy Information Administration, which tracks how often and how long customers lose power, reports that major events such as hurricanes and winter storms account for most of the outage time Americans experience in a typical year. Day-to-day interruptions from equipment problems tend to be shorter.

Duration matters more than frequency for planning. A two-hour outage on a mild evening is an inconvenience. A four-day outage in August heat or January cold is a safety problem, because it affects food, medicine, temperature control and sometimes water.

Ready.gov advises households to plan for outages that could last several days. Utilities restore power in a priority order that usually starts with hospitals, emergency services and major lines serving many customers, then works outward to smaller lines and individual homes. A home at the end of a long rural line, or one with damage to its own service connection, can wait longer than the neighborhood around it.

City living adds its own wrinkles. Elevators stop, electric water pumps in tall buildings may fail, and garage doors and building entry systems can lock up. Our guide on preparing for a power outage in a high-rise covers those building-specific problems in detail.

Think in three time frames

A useful way to plan is to split outages into three windows:

Up to 24 hours: lights, phone charging, information and keeping the fridge closed
One to three days: food safety decisions, temperature control and medical device runtime

Longer than three days: refueling or recharging, water, sanitation and possibly relocating

Each window needs a little more equipment and a lot more planning than the one before it.

What You Actually Need to Power: A Simple Watt Worksheet

Buying equipment before you know your load is the most common mistake in backup power. A small battery pack is useless for a refrigerator, and a large generator is overkill if all you need is a charged phone and a light.

Two numbers drive every decision. Watts measure how much power a device draws at a moment. Watt-hours measure how much energy it uses over time. A 10-watt LED lamp left on for 5 hours uses 50 watt-hours. A battery’s capacity is listed in watt-hours, while generators and inverters are rated in watts.

Here is how to build a worksheet:

List every device you would want during an outage, in order of priority.
Find each one’s wattage on its label, nameplate or power adapter. A plug-in electricity usage meter gives a more accurate reading for appliances that cycle on and off.

Note the startup or surge wattage for anything with a motor or compressor, such as refrigerators, freezers, pumps and some furnace blowers. These can briefly draw much more than their running wattage.
Estimate how many hours a day each item really needs to run.
Multiply watts by hours for each device to get daily watt-hours, then add them up.

Add a margin for losses and surprises before choosing equipment.

A worked example

Consider a hypothetical apartment that needs a 10-watt LED lamp for 5 hours, two phones charged once a day at roughly 15 watt-hours each, and a 60-watt CPAP for 8 hours. That comes to 50 plus 30 plus 480, or 560 watt-hours per day. A portable power station rated around 1,000 watt-hours could cover a day with room to spare, while a phone power bank alone could not.

Add a refrigerator and the numbers change quickly. Refrigerators cycle on and off, so their daily use depends on the model, the room temperature and how often the door opens. The yellow EnergyGuide label on newer models lists estimated yearly energy use in kilowatt-hours, and dividing that figure by 365 gives a rough daily average. A usage meter gives a better answer for your own unit.

Our upcoming watt-hour worksheet guide will walk through this math device by device. For now, the key point is simple: size equipment to the list, not the other way around.

Portable Power Stations

A portable power station is a large rechargeable battery with built-in outlets, USB ports and an inverter. It runs silently, makes no exhaust and can be used indoors, which is why it has become a popular choice for apartments and for powering medical devices at the bedside.

Capacity is listed in watt-hours and output in watts. Both matter. A station with plenty of watt-hours but a small inverter cannot start a refrigerator compressor, while a station with a big inverter and a small battery will run that refrigerator for only a short time.

Some energy is lost when the battery converts stored power into household current. A common planning habit is to assume only about 85 percent of the rated capacity will reach your devices, then divide by the load in watts to estimate run time. Manufacturers publish their own efficiency figures, so check the manual for the model you are considering.

Recharging during a long outage

The limit of any battery is the recharge. Once it is empty, it needs a wall outlet, a car outlet while driving, a generator or solar panels. For outages longer than a day or two, a recharge plan matters as much as capacity.

Chemistry and storage

Many newer stations use lithium iron phosphate cells, which manufacturers generally rate for more charge cycles than older lithium-ion designs. Follow the manufacturer’s storage advice, which often recommends keeping the unit partly charged and topping it up every few months. Store it away from heat, since high temperatures shorten battery life.

Gas, Propane and Dual-Fuel Generators

Fuel generators produce far more power than most batteries and can run as long as fuel lasts. They are the usual choice for households that need to keep a refrigerator, freezer, sump pump, well pump or furnace blower going through a multi-day outage.

There are three broad types:

Conventional portable generators, which are often the least expensive per watt but can be loud
Inverter generators, which produce cleaner power for electronics and usually run quieter and more efficiently at light loads

Standby generators, which are permanently installed, run on natural gas or propane and switch on automatically through a transfer switch

Fuel choice shapes the decision. Gasoline is easy to find but degrades in storage and can be scarce after a big storm, when stations without power cannot pump. Propane stores for long periods in a tank and burns cleaner, though it typically produces somewhat less power per unit than gasoline in the same engine. Dual-fuel models can run on either. Our comparison of propane versus gas generators covers the trade-offs, and our guide on how long a generator runs on a 20 lb propane tank explains the fuel math.

Connecting a generator safely

Ready.gov, the Consumer Product Safety Commission and OSHA all warn against plugging a generator into a wall outlet, a practice called backfeeding. Power can travel back through the home’s wiring into utility lines, where it can injure or kill line workers and neighbors. The safe options are heavy-duty, outdoor-rated extension cords running directly to appliances, or a transfer switch or interlock installed by a licensed electrician.

Maintenance matters too. A generator that sits for a year with old fuel in the carburetor may not start when it is needed. Running it periodically and following the manual’s storage steps keeps it ready.

Solar Charging Basics

Solar panels turn a battery into a renewable system. Paired with a portable power station, folding panels can recharge the battery each sunny day, which stretches a small system across a long outage.

Output is the catch. Panels carry a rated wattage measured under standardized laboratory test conditions, and real-world output is usually lower. Clouds, short winter days, a low sun angle, heat, shade and dust all cut production. The National Renewable Energy Laboratory publishes solar resource maps showing how much sunlight different parts of the country receive, which helps set realistic expectations.

A few practical points:

Match the panel’s voltage and connector to the power station’s solar input limits listed in the manual
Point panels toward the sun and adjust them during the day for better output
Keep panels in full sun, since even partial shade on one cell can sharply reduce output

Plan on solar as a top-up, not a guarantee, especially in winter

Rooftop solar on a house is different. Most grid-tied systems shut down during an outage for safety unless they include a battery and equipment designed to isolate the home from the grid. Homeowners with rooftop panels should ask their installer how their system behaves when the grid goes down.

Safety: Carbon Monoxide, Fire and Fuel

Carbon monoxide is the most serious danger in an outage. It is a colorless, odorless gas produced whenever fuel burns, and it can kill quickly. The Consumer Product Safety Commission warns that portable generators can produce high levels of carbon monoxide, and its guidance is direct: never run a generator inside a home, garage, basement, crawlspace or shed, even with doors and windows open. Operate it outdoors, at least 20 feet from the house, with the exhaust pointed away from windows, doors and vents.

The same rule applies to other fuel-burning equipment. Ready.gov and the CDC warn never to use a gas or charcoal grill, camp stove or other gasoline, propane, natural gas or charcoal-burning device inside a home or garage. A gas oven or stovetop should never be used to heat a home.

Carbon monoxide alarms are the backup. CPSC recommends installing alarms on every level of the home and outside sleeping areas, and testing them regularly. During an outage, hardwired alarms need working backup batteries, so check them before storm season.

Symptoms to know

The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion as common symptoms of carbon monoxide poisoning. People who are asleep or have been drinking can die before they notice anything. If an alarm sounds or anyone feels these symptoms, get everyone to fresh air immediately and call 911.

Fuel and fire

Store gasoline only in approved containers, outside living areas and away from heat sources. Let a generator cool before refueling, since gasoline spilled on a hot engine can ignite. Our guide to storing gasoline long term covers containers, stabilizer and rotation. Candles are a leading cause of home fires, so the American Red Cross recommends flashlights instead.

Keeping Food Safe Without Power

Food is often the most expensive loss in an outage, and the rules are clear. The USDA Food Safety and Inspection Service says a refrigerator will keep food safe for about 4 hours if the door stays closed. A full freezer holds its temperature for about 48 hours, or about 24 hours if it is half full, again with the door closed.

Thermometers make the decisions easier. Keep an appliance thermometer in both the refrigerator and freezer. USDA guidance is to discard refrigerated perishable food such as meat, poultry, seafood, milk, eggs and leftovers that has been above 40 degrees Fahrenheit for 2 hours or more. Frozen food that still has ice crystals or is at 40 degrees or below can be refrozen.

A few steps buy time before the power goes out:

Freeze containers of water or gel packs to fill empty freezer space and help keep food cold
Group frozen foods together so they stay cold longer
Know where to get dry ice or block ice locally

Keep a cooler handy for moving food if the outage drags on

The USDA’s short rule is easy to remember: when in doubt, throw it out. Never taste food to decide whether it is safe.

Lighting, Radios and Phone Charging

Light, information and a working phone cover the basics of the first day. None of them needs much power, which makes them the easiest part of any plan.

For light, Ready.gov and the American Red Cross recommend flashlights and battery-powered lanterns over candles. LED models run far longer on a set of batteries than older bulbs. A headlamp frees both hands for cooking, caring for children or moving around in the dark. Keep spare batteries in the sizes your lights use and check them twice a year.

For information, a battery-powered or hand-crank radio keeps working when cell networks are overloaded or down. The National Weather Service operates NOAA Weather Radio All Hazards, a nationwide network that broadcasts warnings, watches and forecasts around the clock. A radio with the Specific Area Message Encoding (SAME) feature can be programmed to sound alerts only for your county.

For phones, power banks are the first line, followed by a power station or a car charger. Running a car to charge a phone is fine outdoors, but never in a garage, even with the door open. Our guide on charging your phone without power covers every safe option.

Save phone battery

Lower the screen brightness, close apps running in the background, turn on low-power mode and switch to text messages, which use less battery and often get through when calls do not. FEMA and the FCC both recommend texting during emergencies when networks are congested.

Medical Device Backup Planning

For anyone who relies on electricity for health, an outage is a medical issue. Oxygen concentrators, CPAP and BiPAP machines, powered wheelchairs, home dialysis equipment, infusion pumps and refrigerated medicines such as insulin all need a plan.

Ready.gov advises people who use power-dependent medical devices to talk with their health care provider about a power outage plan and to know how long each device’s battery lasts. Device manufacturers can explain battery options and whether a device can run from a power station or car adapter. Some devices are not designed to run on certain kinds of inverter power, so check the manual or call the manufacturer before relying on one.

A few steps help:

Write down each device’s wattage, battery runtime and charging needs
Ask your utility whether it offers a medical priority or medical certificate program, and enroll if one exists
Keep a printed list of medicines, doses and providers
Plan a place to go, such as a relative’s home or a facility with backup power, if the outage outlasts your batteries

Ask a pharmacist how to store temperature-sensitive medicine if refrigeration stops

The FDA notes that insulin can be kept at room temperature for a limited period, which varies by product, so check the package insert for your specific insulin.

Apartment-Friendly Options and a Starter Checklist

Renters and apartment dwellers face limits that homeowners do not. Most leases and building codes ban fuel generators on balconies and in units, and running one in a garage or courtyard near windows is dangerous. Battery-based options fit apartments best: power banks, a portable power station and, where a sunny window or balcony is available, a folding solar panel.

Water is the other apartment concern. Tall buildings often rely on electric pumps, so the taps may stop when the power does. Our emergency water guide explains how much to store and how to keep it safe.

Starter checklist

Use this as a starting point and adjust it for your household:

Flashlights or lanterns for each person, plus a headlamp
Spare batteries in every size your devices use
At least one power bank per phone, kept charged
A battery-powered or hand-crank NOAA Weather Radio
A portable power station sized to your worksheet
Appliance thermometers in the refrigerator and freezer
Battery-powered carbon monoxide alarms and working smoke alarms
A cooler and a plan for ice
A written list of medical devices, runtimes and providers
Cash, since card readers and ATMs may not work
A printed list of key phone numbers
A plan for where to go if heat or cold makes the home unsafe

Temperature control deserves its own plan. Our guides on staying safe in a heat wave and outage and preparing for a winter power outage cover cooling and heating safely when the grid is down.

Frequently Asked Questions

What size power station do I need for a power outage?

Add up the watt-hours your essential devices use in a day, then choose a station with more capacity than that total to allow for conversion losses. Check that its inverter can handle the highest running and surge wattage of anything you plan to plug in.

Can I run a generator in my garage if the door is open?

No. The Consumer Product Safety Commission says never to run a portable generator inside a home, garage, basement, crawlspace or shed, even with doors and windows open. Run it outdoors at least 20 feet from the house with the exhaust pointed away from openings.

How long will food last in the fridge without power?

The USDA says about 4 hours if the door stays closed. A full freezer holds its temperature for about 48 hours and a half-full freezer for about 24 hours. Throw out perishable refrigerated food that has been above 40 degrees Fahrenheit for 2 hours or more.

Is it safe to plug a generator into a wall outlet?

No. Backfeeding a generator through a wall outlet can send power into utility lines and injure or kill line workers and neighbors. Use outdoor-rated extension cords to appliances, or have a licensed electrician install a transfer switch or interlock.

Will rooftop solar keep my power on during an outage?

Usually not by itself. Most grid-tied solar systems shut off during an outage for safety. A system needs a battery and the right equipment to isolate the home from the grid. Ask your installer how your setup behaves.

What should I do first when the power goes out?

Check whether neighbors have power and report the outage to your utility. Keep the refrigerator and freezer closed, unplug sensitive electronics to protect them from surges when power returns, switch to flashlights and tune in to local news or a NOAA Weather Radio.Sources: Ready.gov (Power Outages; Generators; Individuals with Disabilities), U.S. Consumer Product Safety Commission (Portable Generator Safety; Carbon Monoxide Safety), CDC (Carbon Monoxide Poisoning Prevention), USDA Food Safety and Inspection Service (Keeping Food Safe During an Emergency), U.S. Energy Information Administration (electric reliability data), National Weather Service (NOAA Weather Radio All Hazards), National Renewable Energy Laboratory (solar resource data), American Red Cross (Power Outage Safety), FCC and FEMA (communicating during emergencies), U.S. Food and Drug Administration (insulin storage during emergencies), OSHA (portable generator safety). This guide is general preparedness information. Follow the manuals for your equipment and ask a licensed electrician about any connection to home wiring.