The whole home generator vs partial home generator decision is one that every standby generator buyer eventually faces, and it is one that most online resources handle poorly. The answer is not simply that whole-home coverage is always better. It is that the right coverage level depends on your home’s electrical load profile, your budget, your natural gas line capacity, and what you actually need to run comfortably and safely during an outage. This guide gives you a technically grounded, honest breakdown of both options from a Master Electrician-founded team that sizes and sells both configurations every day across all 48 contiguous United States.

Whole Home Generator vs Partial Home Generator: What Each Configuration Actually Means

Before comparing the two approaches, it is worth being precise about what whole-home and partial-home generator coverage actually means in the context of a home standby generator installation, because the terminology is sometimes used loosely in ways that create confusion.

A whole home generator configuration is one where the generator is sized to supply the full electrical load of your home simultaneously, and the automatic transfer switch is configured to transfer every circuit in your main electrical panel to generator power during an outage. When utility power fails, everything in your home continues operating as if nothing happened. Your HVAC system runs. Your water heater runs. Your kitchen appliances run. Your workshop runs. Every outlet and fixture in the building has generator power available.

A partial home generator configuration, also called selected-circuit coverage or essential-load configuration, is one where the generator is sized to supply a subset of your home’s circuits during an outage. The transfer switch transfers only the selected circuits to generator power, leaving others without power until utility service is restored. This configuration prioritizes the circuits that matter most to your household’s safety, comfort, and essential function, while leaving lower-priority loads on the unpowered utility side during the outage.

Both configurations in the whole home generator vs partial home generator decision use the same types of generators and the same types of automatic transfer switches. The difference is in how the generator is sized relative to your home’s total load, and how the transfer switch is configured to route that power. IB Lighting’s electrician-led team works through both options with every generator buyer before recommending one over the other. Explore the full home standby generator collection at IB Lighting here.

Whole Home Generator vs Partial Home Generator: Full Side-by-Side Comparison

What Determines Whether You Need a Whole Home Generator or a Partial Home Generator

The US Department of Energy’s guidance on home heating systems provides a useful reference for understanding how your home’s fuel configuration affects total electrical demand during an outage.

The coverage level question is ultimately a load calculation question. Your home’s electrical load profile, specifically which appliances draw the most power and which you want available during an outage, determines which configuration is appropriate for your situation. Here are the key variables that drive that determination.

Your Home’s Fuel Source for Heating and Cooking

This single variable has the largest impact on the whole home generator vs partial home generator decision for most American households. Here is why.

If your home uses natural gas for heating, cooking, and water heating, your electrical load during an outage is significantly lower than if those same functions are handled electrically. A home with a gas furnace, gas water heater, and gas range primarily needs generator power for the HVAC blower motor, refrigerator, lighting, and outlets. That load profile typically falls in the 10kW to 16kW range for most homes, which a mid-output standby generator can cover comfortably as a partial-to-whole-home configuration depending on the home’s size.

If your home is all-electric, the load picture changes dramatically. An electric water heater draws 4,000 to 5,500 watts. An electric range draws 8,000 to 12,000 watts on full burners. A heat pump for heating draws 3,000 to 6,000 watts. Combined with lighting, refrigerator, and outlet loads, a fully all-electric home’s simultaneous demand during an outage can exceed 20kW to 25kW, placing it firmly in whole-home generator territory at the upper end of Generac’s air-cooled residential lineup.

Your Home’s Square Footage and HVAC Configuration

Home size and HVAC configuration directly affect the generator output required for any coverage level. A 1,500 square foot home with a single 2.5-ton air conditioning system has a meaningfully lower peak simultaneous load than a 4,000 square foot home with two separate 3-ton HVAC zones. Both may qualify as whole-home configurations at their respective output levels, but the generator required to achieve whole-home coverage in each home is very different in size and cost.

For partial-home configurations, HVAC is almost always included in the essential circuit selection because it is the load that most affects household comfort and safety during extended outages. A standby generator sized for partial-home coverage that includes the HVAC system typically needs to deliver at least 12kW to 16kW to handle the HVAC system’s startup surge alongside other essential loads simultaneously.

Whether You Have High-Draw Appliances You Want Covered

Electric vehicle chargers, pool pumps, hot tubs, electric dryers, and whole-home dehumidifiers all represent significant electrical loads that push a partial-home configuration toward whole-home territory when included in the circuit selection. A Level 2 EV charger drawing 7,200 watts added to a standard essential circuit load can push total demand above what a lower-output partial-home generator can supply. Buyers who want EV charging capability during extended outages are almost always in whole-home generator territory regardless of their home’s other electrical characteristics.

Generac Generator Output Levels for Whole Home vs Partial Home Coverage

Generac’s residential air-cooled standby generator lineup spans 7kW to 24kW, covering both partial-home and whole-home configurations depending on your home’s electrical profile. Here is how that output range maps to coverage levels for typical US residential applications.

Generac 7kW to 11kW: Where the Whole Home Generator vs Partial Home Generator Decision Starts

Generac’s 7kW, 10kW, and 11kW air-cooled models are designed specifically for essential circuit coverage in smaller homes or homes where the goal is safety and basic comfort rather than full home operation. These units can typically power a gas furnace blower, refrigerator, well pump, lighting circuits, and select outlets simultaneously. They are not sized for central air conditioning in most residential configurations and are not appropriate for homes where HVAC operation during outages is a priority.

These models represent the most cost-accessible entry point in Generac’s standby lineup and are an appropriate choice for buyers whose homes are primarily gas-heated, whose summers are mild enough that AC is a comfort rather than a safety necessity during outages, and whose budget makes the larger units impractical. Browse the full Generac standby generator lineup at IB Lighting here.

Generac 14kW to 18kW: The Sweet Spot for Partial-to-Whole-Home Coverage

The 14kW to 18kW range is where most residential standby generator purchases land, and for good reason. These output levels cover the full essential circuit load for most American homes including central HVAC, refrigerator, well pump, lighting, and standard outlets with margin to spare. For homes with gas appliances, this range often constitutes effective whole-home coverage because the only high-draw appliances excluded from the essential circuit selection are electric appliances that the home does not have.

For homes with some electric appliances but not a fully all-electric configuration, the 14kW to 18kW range sits in the middle of the whole home generator vs partial home generator spectrum, providing coverage that still delivers a highly livable outage experience. You can run the air conditioning, keep the refrigerator and freezer cold, maintain lighting throughout the home, and power essential outlets while excluding very high-draw loads like an electric water heater or electric range.

Generac 20kW to 24kW: True Whole Home Generator Coverage for Most Homes

The 20kW to 24kW range delivers true whole-home generator coverage for the majority of American homes, including those with all-electric appliances, dual HVAC zones, and high-draw specialty loads. A Generac 22kW or 24kW unit paired with a 200-amp whole-home automatic transfer switch covers the entire electrical panel without requiring any circuit selection or load management during the outage. Every outlet, every appliance, every circuit in the home has power available exactly as it does on utility service.

Generac publishes full residential standby generator specifications and sizing resources at generac.com, which are worth reviewing alongside IB Lighting’s pre-sale sizing guidance before selecting an output level.

For homes above 3,500 square feet, homes with electric water heaters and electric ranges, or homes with EV chargers that the owner wants operational during extended outages, the 22kW to 24kW range is where the whole home generator vs partial home generator question resolves in favor of whole-home without meaningful ambiguity.

Kohler’s Residential Lineup for Whole Home and Partial Home Coverage

Kohler’s residential air-cooled standby lineup from 8.5kW to 20kW covers a similar range of coverage levels as Generac’s mid-tier units. Kohler’s PowerBoost technology, which provides above-rated output momentarily to handle large motor starting loads, means a Kohler 14kW or 20kW unit may handle load scenarios that a comparably rated Generac unit approaches more closely. For buyers choosing Kohler, IB Lighting’s team works through the same load-based coverage determination before recommending a specific output level. Browse IB Lighting’s Kohler generator range here.

Cost Comparison: Whole Home Generator vs Partial Home Generator Total Investment

The whole home generator vs partial home generator cost difference involves more than just the price difference between generator models. The full investment picture includes the generator unit, the transfer switch, installation labor, gas line work, permit fees, and any infrastructure upgrades required.

Equipment Cost Difference Between Coverage Levels

A Generac 14kW standby generator configured for partial-home essential circuit coverage represents a meaningfully lower equipment investment than a Generac 22kW or 24kW unit configured for whole-home coverage. Both Generac and Kohler enforce Minimum Advertised Price (MAP) policies, so final pricing is shown in your cart at IB Lighting rather than on public product pages. To compare pricing across specific output levels before adding to cart, call IB Lighting’s team at (800) 674-9019 and the team will provide accurate pricing for the specific models you are evaluating.

Installation Cost Variables That Affect the Coverage Level Decision

The transfer switch configuration is where whole-home and partial-home coverage diverge most significantly in installation cost beyond the generator itself. A whole-home automatic transfer switch transfers every circuit in your main panel, which requires a 200-amp ATS sized to your panel and wired for full panel transfer. A selected-circuit ATS or load management ATS transfers only the circuits you specify, which may allow a smaller or less complex switch configuration in some installations.

However, for most modern residential installations using Generac’s or Kohler’s standard transfer switch ecosystem, the difference between a selected-circuit and a whole-home ATS is more modest than buyers often expect. The more significant cost variable is often the natural gas line capacity. A larger generator requires a higher BTU gas supply rate, which may require a gas line upgrade that adds cost to the whole-home configuration that a smaller partial-home generator does not require. IB Lighting’s team identifies this variable before recommending a coverage level. Browse the full range of generator transfer switch kits at IB Lighting here.

Operating Cost Difference Over the Generator’s Service Life

When evaluating the whole home generator vs partial home generator operating cost over time, a larger whole-home generator consumes more natural gas per hour at rated load than a smaller partial-home unit. However, because most residential standby generators spend the majority of their runtime at partial load rather than full rated output, the real-world operating cost difference between a 14kW partial-home unit and a 22kW whole-home unit during a typical outage is smaller than the full-load consumption differential suggests. The fuel cost difference over a generator’s 15 to 20 year service life is real but is rarely the deciding factor in the coverage level decision for most buyers.

Which Coverage Level Is Right for Your Specific Situation

Here is how the whole home generator vs partial home generator decision breaks down across the most common buyer profiles IB Lighting’s electrician-led team encounters.

Transfer Switch Configuration for Whole Home vs Partial Home Generator Setups

The transfer switch configuration is different for whole-home and partial-home generator setups, and understanding that difference before you order prevents compatibility problems on installation day.

Whole Home Transfer Switch Configuration

A whole-home generator configuration uses a 200-amp automatic transfer switch that transfers every circuit in your main electrical panel to generator power simultaneously during an outage. The ATS is installed between your utility meter and your main panel, and it transfers the entire panel load to the generator when it detects a utility outage. There is no circuit selection involved. Every circuit in the home transfers automatically.

Some whole-home configurations use a load management or smart load management module that monitors total generator output and temporarily sheds lower-priority loads, such as an electric water heater or EV charger, if the combined simultaneous load approaches the generator’s rated output. This allows a 20kW generator to effectively cover a home with a total connected load that would occasionally exceed 20kW if everything ran simultaneously, by managing which loads are powered at any given moment without any manual intervention from the homeowner.

Partial Home Transfer Switch Configuration

A partial-home configuration in the whole home generator vs partial home generator setup uses a transfer switch that covers only the selected circuits designated as essential loads. This may be a selected-circuit ATS that includes specific breakers from the main panel, or it may be a transfer switch subpanel with dedicated breakers for each selected essential circuit. During an outage, only the circuits wired to the transfer switch subpanel receive generator power. Circuits not included in the selection remain without power until utility service is restored.

Selecting the right circuits for a partial-home configuration is an important part of the pre-installation planning process. IB Lighting’s Master Electrician-founded team helps buyers identify which circuits to include in the essential load selection based on their household’s priorities, safety requirements, and the generator’s output capacity. Browse IB Lighting’s full range of generator transfer switch kits here and visit the Expert Advice hub for detailed guidance on circuit selection before your installation.

Frequently Asked Questions: Whole Home Generator vs Partial Home Generator

The Bottom Line on Whole Home Generator vs Partial Home Generator Coverage

The whole home generator vs partial home generator decision is fundamentally a load calculation exercise, not a values judgment about what constitutes an adequate backup power system. Neither configuration is categorically superior. Each is the right answer for a specific set of home characteristics, priorities, and budget constraints.

For gas-appliance homes where the electrical load during an outage is naturally limited, the whole home generator vs partial home generator answer often resolves in favor of a mid-output 14kW to 18kW unit that delivers effective near-whole-home coverage at partial-home cost. For all-electric homes or homes with high-draw specialty loads, whole-home coverage at 20kW to 24kW is the appropriate solution and the additional investment is justified by the higher load requirements.

IB Lighting carries the full Generac and Kohler residential lineup covering both configurations, ships every order with free nationwide freight delivery and free freight insurance, and has an electrician-led team that performs load-based sizing guidance at no cost before you commit to any purchase. Browse the full home standby generator collection here, or call our team at (800) 674-9019 to work through the coverage level decision for your specific home before you order.