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What Size Generator to Run a 1,500 Sq Ft House?

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When it comes to picking the right backup generator for your home, one of the most important factors is matching the generator's power output to your home's electrical load requirements. For a typical 1,500 square foot house, you'll want a generator sized to comfortably handle the startup and running watt loads of essential appliances and equipment.

What Size Generator to Run a 1,500 Sq Ft House

The goal of this article is to walk through the key considerations for calculating your home's electrical needs and determining the ideal generator size range. We'll provide an overview of the different types of generators, along with specific model recommendations and buying advice tailored to a 1,500 sq ft house. With the right information, you'll be able to choose a generator that provides adequate backup power without wasting money on unnecessary capacity.

Calculating Electrical Load for Your Home

When determining the appropriate generator size, the first step is calculating your home's electrical load - the total amount of watts your home requires to run everything at once. This will determine the minimum generator size needed.

Focus first on major appliances and their typical wattages:

  • Refrigerator - 500-1500 watts
  • Electric stove/oven - 2500-5000 watts
  • Clothes dryer - 1800-5000 watts
  • Dishwasher - 1200-2400 watts
  • Microwave - 800-1200 watts
  • Air conditioner - 1500-4000 watts (for a central A/C unit)
  • Electric water heater - 4000-5500 watts
  • Sump pump - 800-1500 watts
  • TVs - 50-400 watts
  • Computers - 100-400 watts
  • Lights - 15-100 watts each

Tally up the wattage of the essential appliances you require backup power for. Allow about 25% more capacity to account for starting surge wattages. This will provide your estimated electrical load and minimum generator size.

Choosing Generator Type for A 1,500 Sq Ft House

When it comes to powering your 1,500 square foot house, you have two main options for generator types: portable generators or standby generators.

Portable Generators

Portable generators offer flexibility and lower upfront costs compared to standby models. They can be easily moved around on wheels or carrying handles and provide power where it's needed. Most portable models run on gasoline and have power capacities between 3,000 to 10,000 watts. They need to be manually started and connected to appliances with extension cords. Keep in mind that operating portable generators indoors can be dangerous due to carbon monoxide emissions. Unless you are using a solar generator.

Key advantages of portable generators:

  • Lower purchase price ($500-$3,000 range)
  • Can be transported and used in various locations
  • Provide backup power for outages
  • Easier to maintain and repair

Potential downsides:

  • Require manual start and hookup
  • Louder operation (65-80 decibels, The noise of solar generator is generally less than 35 decibels)
  • Limited runtime from small fuel tank
  • Must be operated outdoors for safety

Standby Generators

Standby generators are permanently installed outside the home and connect directly to existing wiring and a fuel supply line. They automatically switch on when the power goes out to restore electricity across pre-selected circuits. Standby units range from about 7-22kW for a 1,500 sq ft house. Natural gas models provide the lowest operating costs.

Benefits of standby home generators:

  • Fully automated operation
  • Whole-house backup or selected circuit coverage
  • Quieter than portable (48-60 decibels)
  • Unlimited runtime from natural gas fuel supply
  • Permanent outdoor installation

Potential downsides:

  • High upfront cost ($3,000-$10,000 installed)
  • Requires professional installation
  • Less portable than wheels-on units
  • Longer repair and service times

Overall, both portable and standby generators have their advantages. Portable models provide more flexibility and lower costs, while standby units deliver automated whole-home backup power.

Generator Sizing Considerations

When determining what size generator you need for a 1,500 square foot house, it's important to understand starting versus running wattage.

The starting wattage is the initial energy surge a device needs to power up and start operating. This can be 2-3 times higher than the running wattage, which is the sustained power needed to continue operating once started.

For example, a refrigerator may have a starting wattage of 1500W but a running wattage of just 600W.

To properly size your generator, you'll want to calculate the starting wattages for all essential appliances, not just the running wattages. This ensures the generator has enough initial surge capacity to start everything up.

It's also wise to add some extra buffer to the total calculated wattage, an extra 10-20% over the estimated needs. This allows for future appliances or expanded use and prevents overload.

Undersizing your generator can lead to overload failures or the inability to start motor-driven appliances like your refrigerator or well pump. It's better to have slightly more capacity than necessary.

The starting wattage requirements and overload buffer are key factors to consider when choosing the right size generator for your 1,500 square foot house. Allowing that extra capacity helps ensure reliable backup power.

What Size Generator Do I Need to Run a 1,500 Sq Ft House?

When it comes to properly powering a typical 1,500 square foot house, a generator in the 7-10kW range is recommended. This will provide enough running watts to handle most of your essential home appliances and equipment.

Specifically, a 7kW generator can safely handle fridges, freezers, furnaces, most lighting, sump pumps, electronics, and some smaller kitchen appliances all at once. For powering larger appliances like electric water heaters, electric stoves, central air conditioning units, and clothes dryers, a 10kW is better suited.

The 7-10kW range hits the sweet spot between providing sufficient power without significant oversizing. It's large enough to prevent overload when multiple appliances start up, yet fuel-efficient for everyday runtime. This capacity will keep your 1,500 square foot house running smoothly during short and extended outages.

Oversizing your generator too much for a typical home this size comes with increased upfront costs and higher fuel consumption. Undersizing can lead to tripping the generator and potentially damage if you attempt to exceed its capacity. That's why a 7-10kW generator optimized for a 1,500 square foot home is recommended by most experts.

Portable Generator Options

Portable generators are a popular choice for many homeowners due to their flexibility and lower upfront cost. Here are some Growatt portable solar generator models to consider for a 1,500 square foot house:

Growatt INFINITY 2000 - Can be Expanded to 6144Wh

Growatt INFINITY 2000 solar generator
  • Fully charge up to 2,048Wh in 2.3 hours of sunlight or 1.6 hours of AC power
  • TT-30 outlet for RVs
  • Can be expanded to 6144Wh

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Growatt INFINITY 1500 - 1512Wh Capacity & 2000W Output

Growatt INFINITY 1500 solar generator
  • Wall charge from 0%-80% in 1 hour;  0-100% in 2 hours
  • Up to 12 Diverse Outlets 
  • Reliable 24/7 backup power (EPS)
  • Easy & Remote Control via  App
  • 2-Year Warranty

Standby Generator Options

Standby generators are permanently installed outside your home and professionally wired to your electrical system. They automatically turn on within seconds when the power goes out.

For a 1,500 sq ft house, you have two standby generator options:

Whole House Coverage

A whole house standby generator provides backup power to your entire home. It starts automatically and runs all your household circuits during an outage.

Whole house coverage requires a larger generator, usually 20-27kW for a 1,500 sq ft home. Though more expensive upfront, a whole house unit delivers complete protection without having to sacrifice appliances.

If budget allows, a whole house generator is ideal for full coverage. It lets you use all your electrical needs like normal during a blackout.

Essential Circuits Only

If budget is a concern, an alternative is a smaller standby generator sized to run essential household circuits only.

For a 1,500 sq ft house, an 8-14kW unit can power basics like the refrigerator, freezer, furnace, lights, and select outlets. Less critical appliances like the dishwasher, stove, and AC may need to be avoided during an outage.

Prioritize the circuits you need most, like your kitchen, laundry room or home office. A smaller generator can run 4-7 essential circuits comfortably.

Though not as convenient as whole house, an essential circuits only standby prevents food loss and provides basic power needs.

What to Consider When Buying A Generator for A 1,500 sq ft House?

When choosing the right generator, there are a few key factors to keep in mind beyond just the power output.

Fuel Type

Most commonly, generators run on gasoline, diesel, propane or natural gas. Gasoline models tend to be more affordable and widely available. Diesel generators have a longer runtime but can be noisy. Propane and natural gas options are clean burning and more environmentally friendly. Consider your fuel storage capacity and availability when deciding.

Noise Level

Fuel type plays a big role in the noise level. Gasoline and diesel generators tend to be the loudest. Look at the decibel rating and sound level at various distances. Quieter inverter generators are available if noise is a concern.


If you want a portable generator, look at the overall weight and dimensions. Wheels and handles can make transportation easier. Smaller portable generators tend to have lower wattage capacity. Prioritize portability or power output based on your main needs.

Frequently Asked Questions

How much do generators for a 1,500 sq ft house cost?

The cost of a generator for a 1,500 sq ft house can range quite a bit based on the fuel type, output power, and features. Expect to pay $500 - $1,500 for a basic portable gasoline generator in the 5,000 to 7,500 watt range. More advanced inverter generators with parallel capability allowing for expansion will be $2,000 - $3,000. Standby generators can cost $2,000 for a basic model up to $10,000+ for a whole house generator running on natural gas or propane.

How much fuel will a generator use for a 1,500 sq ft house?

Fuel consumption depends on the generator's efficiency and power output. For gasoline generators, expect to use around 0.5 to 1 gallon of fuel per hour for a 5,000 watt unit. Propane and natural gas generators can use between 6-10 cubic feet per hour on average. Actual fuel use will vary based on the number of appliances running and generator loading. Conserve fuel by only running the generator when needed.

What maintenance is required for home generators?

Basic maintenance like changing oil, replacing filters, cleaning spark plugs, and inspecting hoses should be done periodically as specified in the generator's manual. Test running the generator monthly and having annual inspections done by a qualified technician can help maximize performance and lifespan. Storing fuel properly and draining old fuel from portable generators is also important. Standby generators may need servicing 1-2 times per year.

Final Tips

When deciding on generator size for a 1,500 sq ft house, it's always best to allow some extra capacity. The starting surge for motors on appliances like the refrigerator or AC unit may require two to three times the amount of power needed during steady operation. Having a generator that's slightly larger than your calculated load will ensure all your appliances can run properly, even with surge demands.

It's also wise to consider potential expandability if you add more electronics or appliances in the future. Don't size your generator for just your current needs - add in a buffer of around 20% extra capacity. This gives you overhead for upgrades like a new washer/dryer, television, or kitchen appliance without requiring an entirely new generator.

Similarly, generators tend to last 10-20 years if properly maintained. Your energy needs may grow over that timeframe, so avoid buying the absolute minimum size required today. Getting a generator that's too small can lead to overload tripping and interruption of power to essential loads.

With thoughtful planning and an understanding of your total load, you can select the right size generator for your 1,500 sq ft house. Allowing some extra capacity provides a cushion for surges and future expansion. A properly sized generator ensures reliable backup power when you need it most.

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