Quick Answer: For a typical whole house, you will likely need a generator in the 15,000 to 30,000-watt range. The exact size depends on the home's square footage and number of appliances. A 15,000-watt unit can cover essentials in a 2,000-square-foot house. Go with a 22,000-30,000 watt generator for a larger 3,000+ square foot home to power AC units, heaters, well pumps and more. Carefully calculate your total home wattage needs, and size the generator to at least double that for safe, reliable backup power.
Introduction
Having a whole-house generator allows homeowners to maintain normal living standards even during extended power outages. Choosing the properly sized unit is crucial to ensure all electrical systems and appliances function when utility power fails. The generator must be large enough to handle the home's total wattage needs while factoring in square footage and future energy demands. This article explains how to calculate your household's electrical requirements and select an adequately powered generator for complete backup capability.
What Factors Determine the Size of Generator You Need?
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The Number of Appliances You Need to Power: If you're looking to power basic appliances like lights, a refrigerator, and Wi-Fi, a small generator may be enough. But if you want to power larger appliances like air conditioners, electric stoves, or washing machines, you'll want to go with a larger wattage.
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Starting Wattage Vs. Running Wattage: When a refrigerator or air conditioner starts up, it requires additional power, called starting power, which is higher than the normal operating power of the equipment. In addition, consider both starting power and operating power to avoid overloading the generator.
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Size of Your Home: Larger homes have more appliances and heating or cooling zones, which means they need a larger generator to meet the increased demand.
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Type of Heating and Cooling System: Air conditioning units, electric heaters, and heat pumps use a lot of electricity. Because these systems are the biggest consumers of electricity in your home, you need to consider them when choosing a generator model.
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Essential Vs. Non-essential loads: Separate essential appliances, like a refrigerator or medical equipment, from non-essential appliances, like a home theater or outdoor lighting. That way, you can adjust the generator's wattage only to meet essential needs during a power outage.
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Fuel Type and Generator Efficiency: Different fuel types (gas, propane, or diesel) and generator models have different efficiencies. Some generators can provide more power using less fuel.
How Do You Calculate Your Home’s Power Requirements?
The most important factor in selecting a whole-house generator is calculating your home's power needs. Add up the wattage of all electrical appliances and devices you'd like to run during an outage. This includes lighting, appliances like refrigerators and freezers, furnaces, security systems, well pumps, and other necessities. As a general guideline, sizing your generator at twice your total wattage needs will provide enough power. It's also smart to factor in future energy needs if you plan to purchase additional appliances. A professionally installed home generator will safely and automatically power appliances and systems during an outage.
Common Household Appliances Power Requirements：
| Appliance | Power Range (Watts) |
| LED Light Bulb | 5 - 15 watts |
| Incandescent Light Bulb | 40 - 100 watts |
| Refrigerator | 100 - 800 watts |
| Freezer | 100 - 800 watts |
| Air Conditioner (Window Unit) | 1,000 - 2,000 watts |
| Central Air Conditioning | 2,000 - 5,000 watts |
| Dishwasher | 1,200 - 1,500 watts |
| Microwave | 600 - 1,200 watts |
| Electric Stove | 1,500 - 5,000 watts |
| Electric Oven | 2,000 - 5,000 watts |
| Washing Machine | 350 - 500 watts |
| Clothes Dryer | 2,000 - 5,000 watts |
| Water Heater (Electric) | 3,000 - 4,500 watts |
| Well Pump | 500 - 1,500 watts |
| TV (LCD/LED) | 50 - 400 watts |
| Laptop | 50 - 100 watts |
| Toaster | 800 - 1,500 watts |
| Coffee Maker | 600 - 1,200 watts |
| Hair Dryer | 1,000 - 1,800 watts |
| Space Heater | 750 - 1,500 watts |
| Electric Blanket | 200 - 400 watts |
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What Generator Size Do You Need for Different Home Sizes?
Once you've calculated your power requirements, you can determine the appropriate generator size. Most whole-house generator systems range from 10,000 watts to 60,000 watts. Here are some typical wattage guidelines based on home square footage:
- Under 2,000 square feet: A 10,000 to 15,000-watt generator can cover essentials like lights, fridges, freezers, furnaces and medical devices. This site is best suited for smaller cottages and cabins.
- 2,000 to 3,000 square feet: Go with a 15,000 to 22,000-watt unit for a moderately sized home. This will allow you to run most appliances, A/C units, sump pumps and other common home systems.
- 3,000 to 5,000 square feet: For larger homes, choose a 22,000 to 32,000-watt generator. This range can handle electric ovens, hot water heaters, multiple HVACÂ units and other major appliances.
- Over 5,000 square feet: Homes over 5,000 square feet often require 36,000 watts or more, especially if you have amenities like a swimming pool, hot tub, or electric vehicle charging. Large custom homes may need 50,000+ watts.
The larger your home's square footage, the more electrical load you'll be drawing. Carefully match the generator's wattage output to your home's size and systems for proper coverage during outages. An adequately sized unit will automatically power your most important appliances.
Can a Portable Solar Generator Power a Whole House?
Well, most portable solar generators lack the power capacity to fully power a complete house. The power output of most mainstream portable solar generators ranges from 100 to 3000 watts. This level of power can run smaller home appliances like phones, laptops, and lighting. However, it's not enough to handle high-draw appliances like air conditioners, water heaters, and electric stoves.
A full-sized home, especially in extreme climates, requires heating in winter and air conditioning in summer. These systems draw over 3000 watts. So, typical portable solar generators struggle to meet the electrical demands of a whole house.
When to Choose Whole House Generators vs. Portable Solar Generators?
| Considerations | Whole House Generator | Portable Solar Generator |
|---|---|---|
| Power Capacity | 10,000 to 60,000 watts, capable of powering the entire house. | 100 to 3,000 watts, suitable for small devices and lights. |
| Suitability Based on Outage | Ideal for frequent and long-duration outages. | Best for infrequent or short-duration outages. |
| Environmental Impact | Higher due to emissions from diesel or natural gas. | Eco-friendly with no emissions and quiet operation. |
| Installation Costs | High upfront cost including installation and potential site preparation. | Low upfront cost with minimal installation needs. |
| Operational Costs | Ongoing costs for fuel and maintenance. | Minimal maintenance; no fuel costs. |
| Scalability | Fixed capacity; challenging and costly to upgrade. | Easily expandable by adding more panels or batteries. |
| Flexibility | Stationary; cannot be moved once installed. | Portable; can be used in various locations as needed. |
| Emergency Preparedness | Can power critical systems such as medical equipment and HVAC. | Limited to charging small devices and powering lights. |
| Impact on Property Value | Can increase home value and appeal in areas prone to outages. | Does not affect property value but offers personal utility. |
Whole house generators are essential for homes needing continuous power for essential and high-wattage appliances during frequent and extended outages. In contrast, portable solar generators are suitable for lighter needs such as charging small devices and powering lights during occasional, brief power interruptions.
Consider also the installation requirements, budget, and environmental impact. Whole house generators require significant initial investment and space for installation, along with ongoing maintenance costs, but they offer comprehensive backup power. Portable solar generators, on the other hand, are more budget-friendly and environmentally friendly, providing a flexible and easily scalable power solution without the need for professional installation.
Conclusion
Reliable backup electricity brings peace of mind when dangerous storms knock out utility power. Carefully calculating your home's total wattage needs and generator sizing guidelines will ensure you choose a system capable of powering essential and everyday appliances. Though whole house units require a bigger investment, their automatic operation and full home coverage provide true energy security. With the right generator sized to your electrical loads and living space, your home will stay powered on even through prolonged outages.
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