Backup comparisons go wrong in a predictable way: they compare capacity and price, and skip the two things that actually decide your experience during an outage — how the power reaches your circuits, and whether anyone has to be home to make it happen.

Here's the method I use across home backup, the debates worth having, and which comparison fits your situation.

How I run a head-to-head

Backup gear gets compared on five axes, in this order:

  1. What it keeps running. Named circuits and appliances, not a capacity figure. "Fridge, internet, two lights, furnace fan" is an answer; "5 kWh" is not.
  2. How the electricity gets there. Extension cords, inlet box, transfer switch or automatic panel. This drives most of the cost difference and almost none of the marketing.
  3. What happens at 3 a.m. Does it switch over by itself, or does someone have to wake up and plug things in?
  4. Total installed cost, including the electrician, not the unit's sticker price.
  5. What you own afterwards. A portable unit moves house with you; a wall-mounted battery does not.

What I won't do is compare a plug-in unit against a permanently installed system on capacity alone and call the bigger one better. They sit at different rungs of the same ladder, at roughly ten times the cost.

The debates that are actually live

Portable versus fixed. The central question in this category, and the one where most money is wasted. A large share of people asking about whole-home backup are describing a problem a portable unit solves for a fraction of the cost.

Battery versus gas generator. Genuinely unresolved for long outages. Silence, indoor safety and zero maintenance against unlimited runtime and lower cost per watt-hour.

Essentials versus whole-home. Less a product debate than an honesty exercise. Central air conditioning, electric water heating and a well pump are what push a system from affordable to a five-figure install — and most households can live without all three for a day.

Expandable versus sealed. Modular systems promise you can grow later. Worth checking what the expansion modules cost before you count on it.

Which comparison you want

If you're trying to work out which rung of the ladder you're on — a plug-in unit or a wired system — read home backup battery vs portable power station. It's the comparison that decides the most money in this category.

If you've established that you want backup but haven't sized it, the comparison won't help until you have: start with the home battery sizing guide. For a verdict on a specific system, see my home backup reviews, and to find out how long any of them lasts on your loads, the home backup calculators.

Frequently asked questions

Should I compare backup systems on capacity or on cost?
On neither, at first. Compare them on what they keep running and how the power reaches those circuits. Capacity only becomes meaningful once you know which loads you are carrying, and installed cost varies far more with the electrical work than with the battery itself. Start with your loads →
Is a bigger battery always better for outages?
No, and it is an expensive way to solve the wrong problem. Beyond a certain point extra capacity sits unused while the constraint is which circuits you can actually reach. Spending on the connection rather than on more kilowatt-hours often buys a better outcome.
Does a home battery pay for itself?
In most places backup is insurance rather than an investment, and it is worth being clear-eyed about that. Batteries can earn their keep where time-of-use electricity rates make it worthwhile to charge cheap and discharge expensive, but that depends entirely on local tariffs and is a separate calculation from outage protection.

All home backup comparisons