Whole-home backup vs essential circuits: which quote is which job

The last outage you sat through is the product. If you lived in the kitchen with a flashlight and the fridge stayed cold, you already know what “essential” felt like. If you wanted the upstairs lights, the dryer, and the AC the whole time, you wanted a different invoice.

Whole-home and essential-only are not two sizes of the same machine. They are two ways of wiring the house. One feeds the whole breaker box. The other feeds a short list and lets the rest go dark.

A salesperson who skips that fork and jumps to kilowatts is selling the chart. Start with which rooms stay on, then pick the switch, then pick the generator or the battery.

The critical-load panel page is how that short list gets its own small box. This page is whether you even want the short list.

Whole-home is the switch, not the square footage

Whole-home backup means the transfer switch sits at service size, often 200 amps, and can feed every circuit in the main panel. Generac describes that as installing the automatic transfer switch between the incoming utility and the home’s distribution panel, so the generator can power the entire site.

Generac: partial vs whole-home transfer switches

That still is not a promise that every load runs at once. A 22 kW air-cooled unit on a 200-amp house will shed the dryer or the range when the well and the air conditioner start together, unless the bid is a much bigger engine. Load-shed modules are how a smaller engine pretends to be whole-home. The load-shed guide is that hardware.

If the quote says “whole home” and the switch is 100 amps, it is not whole-home. It is a limited feed with better marketing.

Essential-only means the electrician moves a handful of circuits into a small extra panel, or into a circuited transfer switch, and the rest of the house stays on the utility and goes dark when the street dies. Generac calls that a partial-home application: the circuits you care about are moved into the switch or a subpanel, and a smaller generator can cover them without trying to start the whole house.

A 10-circuit switch is a common pairing with a portable generator or a small standby. Count a 240-volt breaker as two slots, because it takes two poles. A well plus a dryer will eat the box before you get to lights.

What you actually live with when half the house is dark

Essential-only is a real product, and it is how a lot of people already lived through the last storm. Fridge, furnace blower or boiler controls, sump, well if you have one, one lighting circuit per floor you walk, a bathroom, the garage door if that is how you leave, and the modem plus the little internet box on the side of the house.

Ready.gov starts the same way: take an inventory of what in the house relies on electricity, then plan for it. A closed refrigerator keeps food cold about four hours. A full freezer holds about 48 hours. That is why the fridge is on the list even when you are trying to keep the panel tiny.

Ready.gov: power outages

You will notice what is off. The range, the dryer, the hot tub, whole-house air conditioning, and a Level 2 charger are why people outgrow a small switch. You cook on the gas burners or you eat cold food. You do not run laundry for three days. That is the deal.

Whole-home is the “I don’t want to think about it” story. Lights come back. The thermostat still talks. Someone can take a hot shower if the water heater is gas, or if the generator is big enough for an electric one. You still should not start the well, the AC, and the dryer in the same minute unless the bid says the engine can take that surge.

If you were not home last time, whole-home with an automatic switch is the product that starts without you. Essential-only with a manual switch is a job you have to do in the dark.

The pad and the labor do not get much cheaper

Dealers like to say the jump from a 14 kW essentials package to a 22 kW whole-home package is only a couple thousand dollars on the machine, so you might as well go big. The engine is not most of the invoice.

HomeGuide puts a typical whole-house standby at $6,000 to $11,000 installed, unit plus labor. Longer runs or units over 20 kW land in $9,500 to $24,000. The generator itself is often $3,000 to $6,000. Labor is $3,000 to $5,000, or $5,000 to $12,000+ when the pad is far from the meter or the unit is big.

Their size table (unit only) is a starting map, not a written add-up of your circuits. 13 to 16 kW is $3,000 to $4,500. 17 to 20 kW is $4,000 to $6,000. 22 to 25 kW is $4,500 to $12,000. Generac unit-only averages on that page run from about $3,800 at 16 kW to $5,000 at 22 kW, before pad, gas, switch, and permits.

HomeGuide: whole house generator cost

Consumer Reports, in its 2026 standby ratings, puts the machines they test at $3,400 to nearly $7,000, and installation at about $5,000 to $10,000 or more. They note that smaller units cost almost as much to install as larger ones, because the pad, the gas run, the permit, and the electrician show up either way.

Consumer Reports: best whole-house generators

HomeGuide’s accessory table is the rest of the line items people skip. An automatic transfer switch install is $600 to $2,500. A generator transfer switch job overall is $400 to $2,500. A listed interlock for a portable is $400 to $850 installed. Smart load managers are $130 to $250. A precast pad is $150 to $400. Permits are $80 to $450. Gas line work is $12 to $25 per foot on their table, and a propane tank is $400 to $1,800 if you do not already have one.

That is why a 10 kW essentials job and a 22 kW whole-home job can look closer on paper than the kilowatt gap suggests. You are still pouring a pad, tapping gas, and pulling a permit. The honest delta is the bigger engine, the 200-amp switch, and whatever load-shed they add so the AC does not stall the well.

It is also why “go big, install is the same” is only half true. Fuel use is not the same. HomeGuide puts a 15 to 20 kW standby at $30 to $40 a day on natural gas and $150 to $170 a day on propane if it runs all day. A smaller essentials engine burns less because it is covering less house.

The sizing guide is how big the engine should be once you have picked this fork. The automatic vs manual page is which switch.

Three envelopes that all say “backup”

Bid A, essential-only standby. A 10 to 14 kW air-cooled unit, a small extra panel or a 6- to 10-circuit switch, fridge, heat, sump, well, lights, internet. HomeGuide’s 13 to 16 kW unit band is $3,000 to $4,500 before the pad. Installed, you are often still in their $6,000 to $11,000 typical total if the gas run is short. You live in the kitchen and one bathroom until the utility is back.

Bid B, whole-home standby with load-shed. A 18 to 22 kW air-cooled unit, a 200-amp automatic transfer switch, and modules on the range or the AC so they drop when the well starts. Consumer Reports’ install band of $5,000 to $10,000 or more plus a $5,000 class 22 kW unit is the shape of this envelope. HomeGuide’s over-20 kW installed band of $9,500 to $24,000 is the messy-site version. Ask them to list what gets shed, in order. A 14 kW “whole home” bid that quietly sheds the AC is Bid A with better letterhead.

Bid C, one battery on a short list. EnergySage’s 2026 storage quotes put a typical install around $15,647 before incentives for about 13.5 kWh, the size they associate with a Powerwall 3. Tesla lists Powerwall 3 at 13.5 kWh and 11.5 kW continuous on-grid and backup, with a 10-year warranty. That pack is overnight essentials, not two days of electric heat.

EnergySage: solar battery cost

Tesla: Powerwall

EnergySage’s whole-home battery example is a different order of money: about $34,000 for roughly 30 kWh, three times a partial system in their worked table ($33,840 at 30 kWh versus $11,280 at 10 kWh). Their emergency-backup page groups essential loads as one battery, $5,000 to $18,000, and whole-home as two or three batteries, $24,000 to $40,000.

EnergySage: best batteries for whole-home backup

EnergySage: emergency backup solar

If the machine on the bid is a battery, read usable kWh vs the sticker next. If it is gas on a pad, start with battery vs standby.

When whole-home is the honest product

You have electric heat, two air conditioners, a well, and you were not home last time. A 10-circuit switch cannot hold that. The 200-amp automatic switch is the product, and the engine has to be sized to the greedy starts, not the square footage.

You work from home on a well, and the outage you worry about is days of ice with the gas still up. Runtime is the product. A standby generator on whole-home, or whole-home with the range and dryer locked out, beats a single battery that empties overnight.

You already know you will try to run the house like a normal Tuesday. People do. If the quote is essential-only, you will flip breakers you were told not to flip, or you will be angry that the office circuit was never moved. Buy the switch that matches how you actually behave.

Whole-home still needs a circuit conversation. Electric strips, a heat pump, and a Level 2 charger can eat a 22 kW unit. Ask what gets shed, and in what order, and put that on the bid. The load is still yours to name.

When the short list is the product

The last outage was hours, not days. A tree on a line. The utility switching. You missed the fridge, the furnace click, and the Wi-Fi, and you did not miss the dryer.

Ready.gov’s four-hour fridge window is the planning number, not a reason to also put the range on the panel. The fridge, sump, furnace kit is that short version.

You are willing to live in fewer rooms. That is a cheaper generator, a smaller battery, and a switch you can actually fill without skipping the well.

You already have, or you are buying, one wall battery. EnergySage is blunt that partial backup makes more sense for most American homes, because whole-home is often three times the battery count. EIA puts average household electricity use around 10,500 kWh a year, which is roughly 29 kWh a day if you spread it evenly. One 13.5 kWh pack is about half of that average day. It is several days if you are only running a fridge, lights, and a gas furnace blower.

EIA: electricity use in homes

Adding a circuit later to an essentials panel is an electrician visit. If you already know the garage freezer and the office will bother you on day two, put them on the list now, or admit you are shopping whole-home.

Batteries make the same fork, with a wider gap

On a generator, the expensive parts are the pad, the gas, and the switch, so the jump from 14 kW to 22 kW can look modest next to the rest of the invoice. On a battery, the expensive part is the pack. Whole-home means more packs.

Tesla’s 11.5 kW continuous on Powerwall 3 is a fat hose for one unit. Many homes can start a lot of things at once from a single pack. They cannot run them for long. Kilowatts are the hose. Kilowatt-hours are the tank. Whole-home without enough kWh is a house that looks normal for three hours and then goes dark anyway.

If you have solar, the tank can refill during a sunny outage. That is the battery plus solar story. Do not assume a 2026 federal storage credit on the quote. EnergySage treats whole-home battery money as before incentives, and the residential storage credit followed the end-of-2025 cliff.

A smart panel that can pick circuits from a phone is a third product, not a synonym for whole-home. SPAN-class hardware is a new main. An essentials subpanel is a small extra box. Do not compare those two prices.

What has to be on the bid before anyone pours a pad

Does the switch feed the whole breaker box, or a small extra box? How many amps is it, and is it automatic or a hand switch? Whole-home at 200 amps and essential-only at 100 amps are different parts.

Which circuits stay on, labeled the way they appear in the breaker box, including the ones that stay off? “Whole home” without that list is not a scope.

If the machine cannot run everything at once, which loads get turned off, and in what order? Name the well, the AC, the range, the dryer, and the charger.

How many kilowatts on the fuel you actually have, natural gas versus propane, not only the bigger sticker? How many usable kilowatt-hours if it is a battery, not the brochure tank?

Where does the generator sit, and how far from windows? Ready.gov wants generators outdoors and at least 20 feet from windows, doors, and attached garages. The Red Cross says never power the house by plugging a generator into a wall outlet. That backfeed can kill a lineman. Transfer-switch work is electrician work in most towns.

American Red Cross: generator safety

The placement page is the yard conversation. Who pulls the permit, and who meets the inspector?

A finished scope looks like this: essential-only or whole-home, named in those words; switch amps and type; circuit list as labeled in the panel; load-shed order if any; kW on your fuel, or usable kWh and kW if it is a battery; pad location with the 20-foot exhaust rule if it is an engine. If they cannot fill those, wait on the concrete.

How do I decide this week?

Walk the last outage and write the rooms you actually missed, then keep the dryer and the range off the first list unless you are buying whole-home on purpose.

Ask each bidder whether the switch feeds the whole panel or a small extra box, and make them put the amp rating on the same line as “whole home” or “essentials.”

Price an essentials 10 to 14 kW standby next to a 22 kW whole-home package on the same site, because Consumer Reports is right that install does not drop much when the engine gets smaller.

If the machine is a battery, price one 13.5 kWh pack on a critical-load panel against EnergySage’s $24,000 to $40,000 whole-home band, and do not call the single pack whole-home.

Refuse a 14 kW “whole home” bid that sheds the air conditioner unless the shed list is in writing. That is an essentials job.

Keep the critical-load list and the sizing math on the same kitchen table as this fork. Hire the install that names the switch, the circuit list, and what goes dark.