Home Backup Power in 2026: How to Size a Battery Before You Buy
Most people buy a power station backwards — they pick a number (usually a big one), then discover it will not run the appliance they actually care about. Sizing first takes ten minutes and saves real money.
Step 1: list what you actually need to run
Not everything in your home. During an outage, there is a short list that matters. Typically:
- Refrigerator (the priority — food safety)
- Internet router + modem (so you keep working)
- Phone and laptop charging
- Lights (LED lamps draw very little)
- Medical devices, if applicable
- A fan or small heater, depending on climate
Step 2: understand the two different numbers
This is where most buyers go wrong. Power stations list two specs that sound related but measure different things:
| Spec | Unit | What it means |
|---|---|---|
| Capacity | Wh (watt-hours) | How much energy is stored — the "fuel tank" |
| Output / surge | W (watts) | How much power it can deliver at once — the "engine size" |
A unit with a huge battery and low output cannot start a device with a high surge draw. A unit with high output and a small battery runs out fast. You need both.
Runtime math: hours ≈ (capacity in Wh × 0.85 inverter efficiency) ÷ device watts. A 1,000 Wh unit running a 100 W load gives you roughly 8.5 hours, not 10 — inverters lose energy converting DC to AC.
Step 3: account for surge, not just running watts
Motors and compressors draw a large burst of current at startup. A refrigerator might run at 150 W but surge past 1,000 W for a fraction of a second. If the station's surge rating is below that, it will shut down — even though the math on running watts looked fine.
Rule of thumb: choose an output rating at least 2× the running watts of anything with a motor or compressor.
Step 4: decide on the real use case
| Use case | Typical capacity | Notes |
|---|---|---|
| Phone, laptop, router, lights | 300-500 Wh | Light, portable, cheap |
| Refrigerator + basics for a day | 700-1,200 Wh | The most common home-backup sweet spot |
| Whole-home partial backup | 2,000+ Wh | Significantly heavier and pricier |
Step 5: charging speed is a spec people ignore
If an outage lasts three days, how you refill the battery matters as much as its size. Check:
- AC wall charging speed — some units recharge to 80% in under an hour, others need a full day.
- Solar input capacity — a high Wh battery with a low solar input limit is a mismatch; it will take days to refill.
- Pass-through charging — can it power your devices while it charges? Important during long outages.
⚠️ Before you buy
- Check the output type. Many small "power stations" only have USB ports — no AC outlet. That will not run a refrigerator.
- Weight is real. A 2,000 Wh unit can weigh 20+ kg. If you cannot move it, you will not use it.
- Battery chemistry. LiFePO4 (LFP) cells typically offer far more charge cycles and better thermal stability than older lithium chemistries — worth prioritizing for a device you keep for years.
- Solar panels are often sold separately and can cost as much as the station.
A sensible buying order
- Buy the smallest station that covers your essential list — not the biggest you can afford.
- Confirm the surge rating covers your refrigerator's startup draw.
- Check charging speed, especially solar input if you plan for multi-day outages.
- Add a solar panel only if you genuinely expect outages longer than a day.
Where to compare options
BLUETTI makes LiFePO4-based portable power stations across the 300 Wh to multi-kWh range, which covers most home-backup scenarios.
Compare BLUETTI power stations →Check current capacity, output and pricing · Affiliate link — we may earn a commission at no extra cost to you.
Get the sizing right and a modest station will carry you through a real outage. Get it wrong and an expensive one sits in a closet while your refrigerator defrosts.