How many solar panels are needed to run a 4,000 square foot or larger house?

If you have a very large house, this article will tell you how many solar panels you need to power it.

Photo of a large house.

If you have a very large house, you probably have high electricity usage too, possibly making your home a good candidate for solar.

If you’re curious about solar and want to find out how many solar panels you’d need for your home that is 4,000 square feet or larger, the most accurate way to find that out is to get a professional solar installer to perform an analysis. A quick but somewhat less accurate way is to read your monthly electric bill and use our solar calculator to determine what your power generation and estimated system price would be.

Using the calculator takes only a minute, but if you simply want to know how many solar panels it takes to power a typical 4,000 sqft house based on the average electricity usage across the nation, we can make some assumptions. For other articles on this topic, we’ve relied on data from the US Energy Information Administration, which surveys electricity use by household, but unfortunately their survey doesn’t break out a category for 4,000 sqft homes.

However, we can make an educated guess. According to the survey, homes between 1,500 and 2,999 sqft use remarkably similar amounts of electricity: around 41 million BTUs per year, or about 12,000 kWh. The survey shows a big jump at the next tier, which is 3,000 sqft and larger homes. Because of this, we can assume that very large homes tend to have large electricity usage, possibly because they have appliances that average homes don’t, such as hot tubs or pool heaters.

Based on that, let’s estimate that the average 4,000 sqft or larger house uses 50 million BTUs per year, or 14,654 kWh per year, or 1,221 kWh per month. If that house has a south facing roof without any shading during the day, it would need anywhere between 20 and 31 premium solar panels to generate that much electricity. “Premium” means solar panels with an output rating of about 400 watts, which are the highest efficiency panels currently available. These include, for example, the SunPower A Series and LG NeON 2 series.

Budget solar panels can save you money, but will generate less electricity per panel. The lowest efficiency panels you’ll find on the market have a rating around 250 watts. That average 4,000 sqft home using 1,221 kWh per month would need between 31 and 48 budget solar panels to supply all of its electricity needs.

Why such a big range?

With both these budget and premium examples, we give a pretty big range in the number of solar panels needed. Why is that?

The main reason is that the amount of electricity that solar panels will generate depends heavily on the amount of sunshine you get in your city. It helps to be further south, but local climate is just as important. There are many dry climates in the northern United States that have higher solar radiation than cloudier cities that are further south. Map of solar radiation in the United States. Map of solar radiation in the United States (NREL)

The ranges we give - between 20 and 31 premium solar panels to generate enough electricity for an average 4,000 square foot house - were calculated based on houses located in the cloudy northwest (such as Seattle, Washington) and the very sunny southwest (like Mesa, Arizona). These two cities are at opposite ends of the spectrum when it comes to incoming solar radiation, measured as Direct Normal Irradiance.

Most cities in the continental United States lie between these two extremes and receive an average amount of sunlight, making them perfectly viable for home solar. Check out the map above.

Remember how we said that climate matters just as much southern latitude? If instead of Seattle your average house was located just 140 miles away in Yakima, Washington, you would need only 25 premium solar panels instead of 31. This is because Yakima is in the rain shadow of the Cascade mountain range, and is much drier and sunnier than nearby Seattle. So don’t assume that you can’t go solar just because you live in a northern city.

What’s the biggest electricity consumer in your house?

If your home is typical, your biggest electricity usage is probably for heating, cooling, or both. Because this is climate-dependant, the average household electricity usage depends largely on the region of the country.

However 4,000 sqft and larger homes are quite a bit bigger than the typical house, so this rule of thumb might not apply. Such a large home might have some big-ticket electricity consumers that average homes don’t have, such as pool heating or a hot tub. Plus, it takes more electricity to heat and cool that much square footage.

Electricity usage for home heating

In some places in the United States, you might need home heating only a couple weeks a year. This includes the South Atlantic and Gulf Coast regions, and southern California. For those situations, electric resistance heating tends to be used much more than in states that have several months of heating days.

Electric resistance heating uses electricity to heat a coil, like in a toaster or hair dryer. You’re probably familiar with electric baseboard heaters or small space heaters. Electric resistance heating is inefficient, but it’s handy in regions with low heating requirements because it’s cheap to install and doesn’t require ductwork.

In cold-weather US states with multiple heating months, natural gas is the most popular heating fuel. While a gas furnace does use some electricity to power the fan, it’s a fraction of the power that would be needed for a fully electric furnace.

Note that electric resistance heating is different from highly efficient electric heat pumps, which use electrically-driven compressors to pull heat from the air or ground, much like the way that a refrigerator or air conditioner works. Heat pumps are becoming more popular, even in very cold climates. Many utility companies and local agencies offer rebates on both air source and ground source heat pumps.

Electricity usage for air conditioning

There are many places in the country where air conditioning is nearly a necessity, such as the Southeast where it gets both hot and very humid in the summer. Meanwhile, few homes in the Northwest have central air conditioning, and at most might have a window unit or two for the few weeks where its uncomfortably hot.

A central air conditioner is a big energy hog, drawing a few thousand watts of power while operating.

Electricity usage depends on where you live

Because of the regional differences in climate, average household electricity consumption varies a lot from one part of the country to another. The table below describes the average household electricity usage by region. (Note that this is the overall household average, and not just 4,000 square foot homes.)

Average monthly electricity usage by region

RegionKilowatt-hoursPremium solar panels needed
Northeast68414 - 15
Midwest79714 - 17
South (South Atlantic and Gulf Coast)1,15819 - 24
West (Mountain/Pacific)71013 - 18

This table shows you how much electricity the average household uses in each region, and how many solar panels in that climate are needed to generate that much electricity. Note that some regions, especially the West coast that spans the cloudy Northwest to sunny Southern California, have a lot of variability in solar radiation.

Average monthly electricity usage by climate

Another way of looking at electricity consumption data is by climate instead of geographic region. Here’s a table that shows the average electricity usage by climate in the United States. No solar panel estimates are included this time, because these climates can be found in many different states. Again, these averages are for all households, not just 4,000 sqft houses.

ClimateKilowatt-hours per month
Very cold/cold742

Other household electricity consumers

Heating and cooling aren’t the only electricity requirements in a home, but they tend to be largest. Still, things like televisions, dishwashers, and lighting contribute a significant chunk to the average electricity bill.

This is a table of average monthly electricity use by appliance for all homes in the United States.

ApplianceKilowatt-hours per month
Clothes dryer65
Clothes washer5

How many solar panels will I need for my 4,000 square foot house?

Depending on where you live, your 4,000 sqft house might need between 20 and 31 premium solar panels to supply 100% of its electricity needs. But this is really just an educated guess, and your electricity needs will depend on everything from your local climate to how many televisions you have.

Averages are useful, but if you’re thinking of adding solar panels to your house, start with our solar calculator. Plug in your zip code, and it will automatically tell you what the average household electricity usage is in your state, or you can enter your actual electricity usage.

The calculator will also let you specify the direction of your roof and any shading you have, which will have a major impact on how much electricity your solar panels will generate.

If you’re new to electricity, you can read our article that explains basic concepts such as the difference between kilowatts and kilowatt-hours. Our guide to saving money with solar panels will show you how to read your electricity bill, which can certainly be a complicated document.

Finally, the best way to get an accurate estimate of how many solar panels your house will need is to contact a professional solar installer, who will provide you a technical proposal that outlines how many solar panels you will need and how much power they will generate. If you use our solar quote service, we’ll be sure to connect you with qualified contractors that are licensed to do solar installation in your area.


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