The Question Nobody Answers Directly
Every backup power buyer eventually asks the same question: how much battery do I actually need? The answer they usually get is either vague ("it depends on your usage") or technically accurate but practically useless ("calculate your watt-hours by summing your appliance loads").
This guide gives you a direct answer based on your household's most likely scenario. We've broken it into three distinct outage durations because the right system for a one-day summer thunderstorm is fundamentally different from what you need for a week-long winter ice storm, and pretending otherwise wastes your money in one direction or the other.
Before reading further, use our free power calculator to get a personalized estimate based on your specific appliances. This guide covers the principles and product recommendations, but the calculator does the math for your exact situation in two minutes.
Step One: Decide What You Actually Need to Run
The most common mistake in buying home backup power is trying to power everything. A system sized to run your entire home during an outage is a whole-home battery backup installation, not a portable power station — and it costs $15,000-$30,000 installed.
Portable power stations are the right tool for keeping your essentials running. The question is what "essentials" means for your household.
The Core Four (What Most Households Need)
- Refrigerator: The non-negotiable. Losing $500 worth of groceries during a 3-day outage is a real cost that justifies a significant portion of a power station purchase on its own. A full-size refrigerator draws 100–200W running and consumes approximately 1,000–1,400 Wh per day.
- Lights: LED lighting is remarkably efficient. Four rooms of LED lighting consume roughly 320 Wh per day — a minor load that any mid-size power station handles easily.
- Phone and device charging: Staying connected during an emergency is critical. Phones, laptops, and tablets combined consume approximately 200–400 Wh per day depending on devices and usage.
- Internet router and modem: Often overlooked but important. Your router and modem together draw about 15–20W continuously, or 360–480 Wh per day. Without these, your phone may be your only connection to the outside world.
Total for Core Four: approximately 2,000–2,700 Wh per day.
Situation-Specific Additions
Beyond the core four, your additions depend on your specific circumstances:
- CPAP machine: Add 120–520 Wh per night depending on model and whether you use a humidifier. See our medical device guide for model-specific numbers.
- Well pump: Critical for rural properties. See our well pump guide before buying anything for this use case.
- Sump pump: If you have a basement, a working sump pump during a storm is often more important than a refrigerator. Most 1/3 HP sump pumps draw 250–450W running.
- Security system: Typically 20–60W continuous, adding 480–1,440 Wh per day.
- Window AC: The biggest load most households consider. A 5,000 BTU window unit draws 400–500W running and consumes 2,400–3,600 Wh per day. This single appliance can double your required capacity and is the primary reason many buyers end up needing a large system.
How Much Battery You Need by Outage Duration
Using the Core Four as the baseline (2,200 Wh/day), here's how outage duration translates to required battery capacity. We add a 25% buffer for inverter efficiency losses and cold weather capacity reduction.
| Outage Duration | Core Four Only | + CPAP | + Well Pump | + Window AC |
|---|---|---|---|---|
| 1 day | 2,750 Wh | 3,200 Wh | 3,400 Wh | 7,250 Wh |
| 2 days | 5,500 Wh | 6,400 Wh | 6,800 Wh | 12,000 Wh |
| 3 days | 8,250 Wh | 9,600 Wh | 10,000 Wh | 18,000 Wh |
| 7 days | 19,000 Wh | 22,500 Wh | 23,500 Wh | 42,000 Wh |
These figures assume no solar recharging. If you pair your power station with solar panels, a 400W solar panel can recover approximately 1,600–2,000 Wh on a clear day, dramatically changing the math for extended outages. A 3-day outage effectively becomes unlimited if you have adequate solar input and good sun exposure. We cover solar pairing in detail below.
System Recommendations by Outage Scenario
Most suburban and urban households face outages measured in hours, not days. A mid-size power station in the 1,000–2,000 Wh range handles the Core Four through a 24-hour outage and costs significantly less than the large systems marketed for "whole home" backup.
Best choices:
Hurricane, major winter storm, and wildfire PSPS outages commonly last 2–5 days. This scenario requires either a large-capacity single unit or a base unit plus expansion battery. Pairing with solar panels is increasingly practical at this tier.
Best choices:
Extended outages of a week or more require a system designed around solar recharging, not just battery capacity alone. No practical portable power station stores enough energy to run a household for 7+ days without solar input. The goal is a system that recharges faster than you consume it.
Best choices:
Pairing Solar Panels: When It Makes Sense
Solar recharging transforms a portable power station from a finite battery into a sustained energy source. But whether it makes sense depends on your situation.
Solar makes sense if:
- You're planning for outages longer than 48 hours
- You live in a region with reliable sun exposure (the Southwest, Southeast, and much of the South)
- You want to reduce reliance on AC recharging between outages
- You're considering an off-grid cabin or outbuilding application
Solar is less effective if:
- Your outages are short (under 24 hours) — you won't need to recharge
- You're in a region prone to extended overcast periods during storms (the Pacific Northwest during winter)
- Your roof or property has limited south-facing, shade-free exposure
For most home backup applications, a 200W portable solar panel paired with a mid-size power station provides meaningful runtime extension for under $300 additional cost. A 400W panel setup significantly changes the math for extended outages — potentially giving you indefinite runtime on essentials during a clear weather outage.
Gas Generator vs. Solar Generator: The Real Comparison
The traditional alternative to a portable solar power station is a gas generator. Here's the honest comparison:
| Factor | Gas Generator | Solar Power Station |
|---|---|---|
| Upfront Cost | $400–$3,000 | $600–$5,000 |
| Ongoing Fuel Cost | $5–$20/day in operation | $0 (solar) or small electricity cost to recharge |
| Fuel Availability in Disaster | Often scarce after major events | Not applicable |
| Indoor Use | Never — carbon monoxide risk | Yes, completely safe indoors |
| Noise | 60–80 dB (very loud) | Silent or near-silent |
| Maintenance | Oil changes, carb cleaning, regular runs | |
| Continuous Runtime | Unlimited with fuel | Limited by battery/solar unless expandable |
| Power Output | Higher (5,000–12,000W typical) | Lower (1,800–4,000W typical) |
The honest summary: gas generators win on raw power output and unlimited runtime. Solar power stations win on convenience, safety, indoor use, noise, and total cost of ownership over time. Most households preparing for typical storm season outages are better served by a solar power station. Households with very high power requirements (central AC, multiple large appliances simultaneously) may still need a gas generator or a whole-home battery system.
What the Warranty Actually Covers
This is where reviews almost universally fail buyers. The warranty number on the box doesn't tell you anything useful. What matters is what the process actually looks like when something goes wrong.
EcoFlow: Standard 2-year warranty with a ship-back-for-replacement process. Turnaround typically 2–3 weeks. Customer support phone line is generally responsive. Known issue: replacement units are sometimes refurbished rather than new, which is disclosed but worth knowing.
Jackery: 2-year warranty, 3 years with product registration. Process is ship-back with replacement. Support quality is generally positive in owner forums. Registration step is important — without it you get one fewer year.
Bluetti: 2-year warranty with a historically somewhat slower support response compared to EcoFlow. Product quality is strong; the support differential is worth noting for buyers who prioritize service response speed.
Anker SOLIX: 2-year warranty backed by Anker's established consumer electronics support infrastructure. Generally considered strong support relative to the category.