How many solar panels are needed to run a 2,500 square foot house?

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

Aerial photo of some average size houses.

Are you thinking about going solar, and you’re wondering how many solar panels you’ll need for your 2,500 square-foot house?

The most accurate way to find that out is to get a professional solar installer to perform an analysis on your home. 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 2,500 sqft house based on the average electricity usage across the nation, here it is. According to the Energy Information Administration (EIA), the average house in the United States between 2,500 and 2,999 sqft in size uses 12,280 kWh annually, or 1,023 kWh per month.

If that house has a south facing roof without any shading during the day, it would need anywhere between 17 and 26 premium solar panels to generate that much electricity. In this case, “premium” refers to solar panels with an output rating of 400 watts or more, which are the highest output panels currently available. These include, for example, the SunPower A Series and REC Alpha Pure.

At the moment, the highest output panel for home use is the SunPower M-Series, which tops out at 440 watts. (You can read more about 400 watt panels in our article on the topic.)

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 300 watts. That average 2,500 sqft home using 1,023 kWh per month would need between 26 and 40 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 17 and 26 premium solar panels to generate enough electricity for an average 2,500 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 21 premium solar panels instead of 26. 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?

Unless you have a swimming pool, your biggest electricity usage is probably for heating, cooling, or both. Because this is climate-dependant, what the average household electricity usage is depends largely on what part of the country you live in.

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 2,500 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 2,500 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 2,500 square foot house?

Depending on where you live, the average 2,500 sqft house will need between 17 and 26 premium solar panels to supply 100% of its electricity needs. But as you can see from the data above, how much electricity your house uses depends 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.


#System Design #Panel Efficiency

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