Lauren HollandBy Lauren Holland

Updated November 2026

Home power backup solutions keep the essentials running when the grid goes down, and the right choice depends on what you need to power and for how long. In this guide, you will list your critical loads, estimate your daily energy use in watt-hours, compare the main backup options, and arrive at a system size you can actually defend. The method works whether you are planning for a single overnight outage or a multi-day storm.

Start With a List of Critical Loads

Before you look at any hardware, write down exactly what has to keep running. Most households find that only a handful of appliances matter during an outage. Everything else, including electric water heaters, dryers, electric ranges and central air conditioning, is usually better left off or handled with a separate plan. Keeping the list short is the single biggest lever on cost and size.

Shopping for one? See our guide: Top 5 EcoFlow Power Stations with Solar Panel Options for Home Backup (2026).

Common critical loads include:

  • Refrigerator and freezer
  • Medical devices such as a CPAP machine, oxygen concentrator or insulin refrigerator
  • Sump pump or sewage ejector pump
  • Wi-Fi router and modem
  • LED lighting in a few key rooms
  • Phone and laptop charging
  • A window air conditioner or space heater, if your climate calls for it

If anyone in the house depends on powered medical equipment, confirm your plan with the equipment manufacturer and your physician or durable medical equipment provider. Oxygen and life-support devices carry specific requirements that a general guide cannot cover.

Calculate Your Daily Watt-Hour Needs

Watt-hours (Wh) measure energy, and they are the number that matters when you compare battery systems. The formula is simple: multiply the appliance’s power draw in watts by the hours it runs per day. Appliance labels or manufacturer spec sheets usually list wattage. For cycling devices like a refrigerator, the label often gives a daily kilowatt-hour figure, which you can convert by multiplying by 1,000.

Worked Examples

  • Refrigerator: Many modern refrigerators use roughly 1 to 2 kWh per day, or about 1,000 to 2,000 Wh. Compressors cycle on and off, so the average draw is far below the running wattage.
  • CPAP machine: Typically 30 to 60 watts while running. An 8-hour night at 45 watts is about 360 Wh. Check your device’s spec sheet, since humidifier settings change the number.
  • Sump pump: A 1/3 HP pump may draw around 800 to 1,000 watts while running, but it only runs in short bursts. Estimate a few minutes per hour during heavy rain and budget accordingly.
  • Wi-Fi router and modem: Usually 10 to 20 watts combined, or about 240 to 480 Wh over 24 hours.
  • LED lights: A 10-watt LED running 5 hours uses 50 Wh.

Add a Safety Margin

Your raw total is not enough. Inverters and batteries lose some energy in conversion, and batteries should not be drained to zero for long-term health. A common planning approach is to add 20 to 30 percent to your daily total and then divide by the usable depth of discharge the battery specifies. Multiply the adjusted total by the number of outage days you want to cover, and you have a target capacity.

Compare the Main Types of Home Power Backup Solutions

Home power backup solutions fall into a few categories, each suited to different situations. Portable power stations are lithium battery units with built-in inverters and outlets, and they can be recharged from a wall outlet, a car or solar panels. Standby generators run on natural gas, propane or diesel and can handle much larger loads. Whole-home battery systems integrate with your electrical panel and can cover most of the house. Your choice depends on budget, outage length, and how much of the house you want powered.

Option Typical use Strengths Limitations
Portable power station Fridge, CPAP, lights, devices Quiet, indoor-safe, easy to move, solar-compatible Limited capacity for high-draw appliances
Standby generator Large portions of the home Long runtime, automatic start Installation cost, fuel supply, noise, outdoor placement
Whole-home battery Most circuits, with load management Seamless switchover, can pair with solar Professional installation, higher upfront investment
Portable generator Short outages, selected loads Lower initial outlay, flexible Carbon monoxide risk, must run outdoors, fuel storage

For many households with a few critical loads, a portable power station is the most practical starting point. If you want to explore that route, Home Backup Power Systems: A Step-by-Step Guide to Sizing for Outages (2026) walks through sizing in more detail, and Best Backup Power Supply for Home: 6 Factors to Size It Right (2026) covers the factors that drive the choice.

Plan a Solar Recharge Option

Battery capacity alone only covers so many hours. For multi-day outages, you need a way to recharge. Solar panels paired with a compatible power station are a common answer. Panel wattage determines how fast you can recharge under good sun, but real-world output drops with clouds, shade, panel angle and season. Plan for a fraction of the rated panel output, not the full number.

If you are considering solar, Solar Power Backup System for Home: A Step-by-Step Sizing Guide (2026) explains how panel output translates into daily energy, and Home Backup With a Solar Generator: What It Can Power and How to Connect Safely covers connection practices.

Consider Whole-Home Options for Larger Needs

If your list includes central air, an electric range or a well pump, portable units may fall short. Whole-home systems tie into your main panel and manage loads so the most important circuits stay powered. Sizing these systems requires a load calculation, usually done with a licensed electrician. A useful starting point for reading about these setups is Whole Home Power Backup System: How to Size One for Outages (2026).

Step-by-Step: Sizing Your System

  1. List every critical load and its wattage from the label or spec sheet.
  2. Estimate daily run hours for each load, using real-world habits.
  3. Convert each load to watt-hours per day and total them.
  4. Add a 20 to 30 percent margin for conversion losses and battery health.
  5. Decide how many outage days you want to cover.
  6. Divide the adjusted daily total by the battery’s usable depth of discharge to find the minimum capacity.
  7. Check peak wattage: the inverter must handle the startup surge of motors, such as a refrigerator compressor or sump pump.
  8. Plan a recharge method, whether grid, car, generator or solar.

Tools and Checklist Before You Buy

  • A printed load list with wattages and daily hours
  • A kill-a-watt style plug-in energy meter to measure real appliance use
  • Your home’s electrical panel layout, if considering a transfer switch
  • Outlet and cable inventory, so you know what plugs you need
  • A dedicated outdoor or ventilated spot for any fuel-burning equipment

A plug-in energy meter is one of the most useful tools for sizing, because appliance labels often overstate or understate real use. Measuring your refrigerator or CPAP for a few days gives you numbers you can trust.

A portable power station with a pure sine wave inverter is the typical choice for sensitive electronics and medical devices. Look for a unit whose surge rating covers your sump pump or refrigerator startup. View on Amazon

Foldable solar panels suit portable power stations and give you a recharge option during extended outages. Check that the panel connector matches your power station’s input. View on Amazon

A heavy-duty extension cord rated for outdoor use reduces the risk of overheating when running appliances from a power station. View on Amazon

Common Mistakes

  • Sizing for peak instead of daily energy. Battery capacity is about watt-hours, not the peak wattage of your largest appliance.
  • Forgetting startup surge. Compressors and pumps can draw several times their running wattage for a moment.
  • Ignoring depth of discharge. Using the full rated capacity overstates how much you actually get.
  • Running a generator indoors. Fuel-burning equipment produces carbon monoxide and must stay outdoors, away from windows and vents.
  • Plugging a generator into a wall outlet. This creates backfeed hazards for utility workers. Use a properly installed transfer switch.
  • Testing only once. Run your system through a test outage every few months to confirm it works and the battery holds charge.

Tips

  • Start with the fridge and medical devices, then expand.
  • Keep batteries charged during storm season, not just during an emergency.
  • Store a few days of fuel or plan a solar recharge for extended outages.
  • Label your critical circuits so anyone in the household can operate the setup.
  • Review your list each year, since new devices change the math.

FAQ

How many watt-hours do I need to run a refrigerator overnight?

A typical refrigerator may use around 1 to 2 kWh per day, so an overnight outage of 8 to 10 hours often requires roughly 400 to 800 Wh, depending on the model, temperature settings and how often doors open. Measuring with a plug-in meter gives the most accurate figure.

Can a portable power station run a CPAP machine all night?

Many CPAP machines draw a modest amount of power, often under 60 watts, so a mid-sized power station can usually cover a full night. Confirm your device’s specifications and consult your sleep provider before relying on any backup.

Will a backup system handle my sump pump?

It can, if the inverter’s surge rating covers the pump’s startup current and the battery has enough capacity for repeated cycles during heavy rain. Because sump pumps often run during the same storms that cause outages, plan for more energy than the pump’s average draw suggests.

What is the difference between a power station and a generator?

A power station stores energy in a battery and delivers it through an inverter, so it runs silently and can be used indoors. A generator burns fuel to produce electricity and must be operated outdoors due to carbon monoxide.

Do I need an electrician to install a whole-home backup system?

Yes. Connecting a battery or generator to your main panel requires a transfer switch or interlock installed by a licensed electrician and, in many areas, a permit. Consult a qualified professional for any panel-level work.

How long do lithium backup batteries last?

Manufacturers typically specify a cycle life, meaning the number of full charge and discharge cycles before capacity drops to a stated percentage. Lifespan depends on usage, temperature and depth of discharge, so check the spec sheet for your model.

Can solar panels fully recharge a backup system?

They can, but output depends on sunlight, panel size and weather. Plan for lower real-world output than the panel’s rated wattage, and expect longer recharge times during cloudy periods.

Conclusion

Effective home power backup solutions start with a clear list of critical loads and a watt-hour estimate, not with the largest unit you can afford. Choose a technology that fits your outage length and the appliances you need, then add a recharge plan such as solar or a generator. Test the system regularly, and consult a licensed electrician or medical provider for anything involving panels or life-sustaining equipment.

Ready to choose one?

Lauren Holland

About Lauren Holland

Lauren Holland is part of our editorial team and reviews and edits our solar generators for home backup & emergencies guides, checking product details against manufacturer specifications and owner feedback.