How to Choose Backup Power for Your Home
A useful backup-power system starts with the appliances you actually need to run—not the largest battery or highest advertised wattage. This guide explains how to size your setup and compare portable batteries, fuel generators, and integrated home systems.
Step 1: List Your Essential Loads
Identify the devices that matter during an outage: phone charging, Wi-Fi, lighting, refrigerator, freezer, fans, and any medically necessary equipment. Read each device’s power label or use a watt meter; do not assume every refrigerator or medical device uses the same amount of power. Record its running watts, startup surge if applicable, and the number of hours you need it.
Step 2: Separate Watts from Watt-Hours
Watts 
measure instantaneous power draw. Watt-hours (Wh) measure stored energy. As an illustration, a 50W load running for 8 hours consumes approximately 400Wh before battery and inverter losses. A 1,000Wh battery will not necessarily deliver 1,000Wh to an AC appliance; allow for conversion losses, standby consumption, temperature, and battery operating limits.
Step 3: Choose a Practical Size
- 200–500Wh: charging phones, laptops, routers, and lights.
- 500–1,000Wh: longer use of several low-wattage essentials.
- 1,000–2,500Wh: selected appliances when their running and surge requirements are compatible.
- 3,000Wh and above: larger backup loads or expandable systems, often with greater weight and installation complexity.
These are shopping ranges, not promises that a given unit will operate a particular appliance.
Step 4: Compare More Than Capacity
Evaluate continuous AC output, surge rating, 120V/240V compatibility, usable battery capacity, LFP battery chemistry, recharge time, solar input, UPS or switchover behavior, operating noise, weight, warranty terms, and available service support. Check whether accessories or expansion batteries cost extra.
Step 5: Understand Safety and Installation
Fuel-powered generators must be operated outdoors at least 20 feet from the home, with exhaust directed away from openings; never run one in a garage or enclosed area. Maintain working carbon-monoxide alarms. Never backfeed house wiring through a wall outlet. A qualified electrician should install appropriate transfer equipment for home integration.
Safety references: CDC power outage guidance and FEMA generator guidance.
Our Editorial Approach
We compare manufacturer specifications, safety documentation, warranty support, and credible independent performance evidence. Research candidates are not final recommendations. Homeowner Edge USA has not performed hands-on testing of the products currently listed.
Illustrative Runtime Calculator
Use this planning formula: estimated AC runtime (hours) = battery capacity (Wh) × assumed usable fraction ÷ device draw . For the examples below, we assume 80% of the nameplate energy is delivered to the appliance. This is an illustrative planning assumption, not a measured efficiency rating or guaranteed runtime.
| Battery capacity | 50W continuous load | 100W continuous load | 200W continuous load |
|---|---|---|---|
| 288Wh | 4.6 hours | 2.3 hours | 1.2 hours |
| 768Wh | 12.3 hours | 6.1 hours | 3.1 hours |
| 1,070Wh | 17.1 hours | 8.6 hours | 4.3 hours |
| 3,840Wh | 61.4 hours | 30.7 hours | 15.4 hours |
Actual results vary with inverter losses, battery management, ambient temperature, age, and low-load standby consumption. For refrigerators, compressors cycle on and off and may have a startup surge; use measured average energy consumption and verify inverter surge compatibility. Never use these estimates as the sole basis for life-sustaining medical equipment backup planning.
Before You Buy: Five Questions
- What devices must operate, and what are their measured running and startup watts?
- How many hours or days of backup do you need between recharges?
- Will you recharge from a wall outlet, vehicle, solar panels, or a combination?
- Do you need standard 120V outlets, 240V compatibility, or an electrician-installed transfer solution?
- What are the full costs of cables, solar panels, expansion batteries, warranty coverage, and delivery?
