The right generator size depends on what you want to keep running during an outage and how much power that equipment uses. Square footage alone does not tell you what size generator your home needs.
Standby generators are rated in kilowatts, or kW. Home Power Systems calculates the electrical loads in your home before recommending equipment.
What Does Generator Size Mean?
A generator's kW rating tells you how much electrical power it can supply. A light uses far less power than a central air conditioner, heat pump, or well pump.
Some equipment also needs extra power for a few moments when a motor or compressor starts. Generator sizing needs to account for that temporary demand.
Start by Deciding What You Want the Generator to Power
Think about what you would need during an outage. That can include:
- Heating equipment
- Refrigerator and freezer
- Sump or well pump
- Lighting
- Internet equipment
- Medical equipment
- Kitchen appliances
- Air conditioning
You do not have to back up every circuit. The equipment you choose determines how much generator capacity you need.
Essential-Load vs. Whole-Home Generator Sizing
Essential-Load Generator
An essential-load setup supplies selected circuits during an outage. You might prioritize heat, refrigeration, a sump pump, lighting, and other equipment you do not want to lose.
Broader Whole-Home Coverage
Broader coverage lets the generator support more equipment around the house. As the electrical load increases, the generator needs enough capacity to handle it.
Load management can control when certain large electrical loads are allowed to run.
How HVAC Equipment Affects Generator Size
Heating and cooling equipment can make a big difference in generator sizing. A gas furnace needs electricity for the blower and controls, while a heat pump uses electricity for heating.
Central AC, boiler pumps, and electric resistance backup heat have different electrical requirements. We check the equipment in your home instead of using one HVAC number for every house.
Why Starting Watts Matter
Motors and compressors can draw extra power when they first turn on. Air conditioners, heat pumps, sump pumps, and well pumps are common examples.
The generator needs enough capacity to handle that brief increase while other equipment is running.
Does House Size Determine Generator Size?
Not by itself. Two homes with similar square footage can have very different electrical needs.
One house may use gas for heat and cooking, while another uses more electric equipment. Homeowners can also choose different circuits for backup power.
What Is Load Management?
Load management controls when larger electrical loads can use generator power. It can give essential equipment priority and keep several high-demand loads from starting together.
SPAN smart electrical panels can provide circuit-level monitoring and load management for homes where that type of control is needed.
Generac vs. Kohler Generator Sizes
Generac and Kohler both make standby generators in several capacities.
Home Power Systems installs Generac standby generators and Kohler standby generators. We select equipment based on the calculated load, fuel setup, and installation requirements.
What Happens During a Professional Generator Sizing Assessment?
We ask what you want to keep running during an outage, then check the electrical service and the equipment connected to those circuits.
We calculate the electrical demand, review the fuel setup, and determine the generator capacity needed for the house.
Generator placement is planned separately from capacity. Our generator installation examples show how standby equipment has been placed at other homes.
Should You Buy a Larger Generator Than You Need?
Bigger is not automatically better. A larger generator can cost more, use more fuel, take up additional space, and provide capacity you do not need.
The generator should match the electrical load it is expected to carry.
Generator Sizing for Buffalo, Rochester & Syracuse Homes
Upstate New York homeowners may want backup power for heating equipment, refrigeration, sump pumps, well pumps, and other household needs during an outage.
Which equipment gets backup power is up to you. We calculate what those circuits require before selecting the generator.
Schedule a Generator Sizing Assessment
Home Power Systems can calculate your home's electrical load and help you choose the generator size for the equipment you want backed up. Our standby generator installation service covers the planning, electrical work, equipment installation, and startup.
Request an In-Home Generator Assessment
Schedule Online or Call (716)-314-1743
FAQ
How many kilowatts does a whole-house generator need?
There is no single size for every home. The required capacity depends on the electrical load the generator needs to support.
Can a 20 kW generator power an entire house?
It depends on the home's electrical load. A 20 kW generator can support some homes but not others.
Does generator size depend on house square footage?
Not by itself. The electrical equipment and circuits you want backed up determine the required capacity.
What appliances use the most generator power?
HVAC equipment, electric heating equipment, pumps, and other large appliances can require significant power.
Can load management reduce the generator size I need?
Load management controls when large loads operate and can affect how the system is sized. Final sizing still requires a load calculation.
