What Backup Power Actually Costs

Backup power has three costs and most buyers only plan for the first one. Understanding all three is the difference between a project that lands on budget and one that stalls halfway through because the electrician's quote was a surprise.

Cost one: the machine

This is the number everyone shops. It scales with running watts, fuel count, and start method, and it is the cost you have most control over — chiefly by not buying more generator than your load needs. The sizing calculator is the cheapest money-saving tool on this site for exactly that reason.

We do not print prices in prose anywhere on this site. Prices move constantly, and a figure typed into a page is wrong within days. Every price you see here comes from a live data feed with the date it was checked attached, and when that feed goes stale the number disappears rather than misleading you. The purchase cost guide explains what drives the price rather than quoting one.

Cost two: the connection — the one people miss

A generator that cannot reach your furnace is not a backup power system. The connection adds, at minimum:

• The switch or interlock. A 10-circuit 30 A transfer switch, or an interlock plate costing a fraction as much.
• An inlet box, unless the switch has one integrated.
• A cord of the right gauge, connector type and length.
• A licensed electrician, plus a permit and an inspection in most jurisdictions. On a 50 A installation the heavier conductors push this higher.

On a correctly sized setup the connection is commonly a meaningful fraction of the total — and going from 30 A to 50 A raises every line of it. That is one more reason to size from your actual load: a lower wattage class often means a 30 A connection instead of a 50 A one, which saves money twice. Transfer switch installation cost sets out what the quote is made of.

Cost three: fuel, which depends entirely on load

Fuel burn is not a fixed property of a generator — it tracks how hard you are working it. A machine at 25% load may run 14 hours on a tank and the same machine at 50% load 9.5 hours. That is why we will not publish a cost-per-hour figure: it would be a guess about your load and your local fuel price, both of which we cannot know.

Instead, the fuel cost calculator takes your fuel price and your load and does the arithmetic in front of you, with the formula shown so you can check it. The rough ranking it will show you:

The comparison almost nobody runs

Total cost of ownership over five years, generator against battery. A battery costs more up front per watt, and then costs almost nothing: no fuel, no oil, no filters, no spark plugs, no stale-fuel failures, and a LiFePO4 pack rated for thousands of cycles. A generator is cheaper to buy per watt and has a running cost and a maintenance schedule attached forever.

For a household with short, infrequent outages and small essential loads, the battery frequently wins on five-year cost as well as on convenience. For a household with a well pump and multi-day outages, it does not come close. Power station vs generator cost of ownership runs it both ways.