How Many Solar Panels Do I Need To Power a House?

How Many Solar Panels Do I Need To Power a House?

One of the first questions homeowners ask when going solar is “How many solar panels do I need to power my home?”

The goal for any solar project should be 100% electricity offset and maximum savings — not necessarily to cram as many panels on a roof as possible. So, the number of panels you need to power a house varies based on three main factors:

• Electricity Consumption
• Sun exposure
• solar panel power rating

In this article, we’ll show you how to manually calculate how many panels you’ll need to power your home. If you’d rather skip the math, connect with an Energy Advisor to design a custom solar system.

How many solar panels do you need to power a house?

While it varies from home to home, the US households typically need between 10 and 20 solar panels to entirely offset their average annual electricity consumption.

The goal of most solar projects is to offset your electric bill 100%, so your solar system is sized to fit your average electricity use. Here’s a basic equation you can use to get an estimate of how many solar panels you need to power your home:

Solar panel wattage x peak sun hours x number of panels = daily electricity use

Obviously, electricity use, peak sun hours, and panel wattage will be different for everyone. And since you didn’t come here to do algebra, we’ll go through how to figure out each variable and run through an example scenario based on national averages.

First, identify your average daily electricity usage

According to the US Energy Information Administration (EIA), the average US household in 2020 used 10,715 kilowatt-hours (kWh) of electricity per year. That’s equal to:

• 893 kWh per month
• ~30 kWh per day

It’s important to note that this usage varies quite a bit from state to state. For example, the average daily usage was ~18 kWh in Hawaii and 40 kWh in Louisiana, which is quite a spread. But we’ll use the national average 30 kWh per day as the figure for our example.

The easiest way to find your daily electricity usage is to dig up some recent utility bills. Your bill should show your usage for 30 days (or whatever your payment period is) and you can use this to get a sense of your daily electricity consumption. Just take the total usage during the period, and divide it by the number of days.

Electricity usage varies from month to month, so the more bills you can average together, the more accurate your calculation will be.

Once you have your daily electricity usage, the next step is to figure out how many peak sun hours your system will get per day!

Next, determine how many peak sun hours your location gets

A big factor in determining how many solar panels you need to power your home is the amount of sunlight you get, known as peak sun hours.

A peak sun hour is when the intensity of sunlight (known as solar irradiance) averages 1,000 watts per square meter or 1 kW/m2.

In the US, the average peak sun hours range from over 5.75 hours per day in the Southwest to less than 4 hours per day in the northernmost parts of the country.

 

Use the map above to estimate the average peak sun hours for your area, or use this peak sun hours calculator to get a precise figure for your location.

Here are some tips for using the peak sun hours calculator:

• The average roof pitch is between 14 and 27 degrees
• Use the compass on your phone to determine the Azimuth Angle of the roof face you’d put solar panels on (closest to 180 degrees is best)

Based on the map, about half the US gets less than 4.5 peak sun hours and half gets more, so we’ll use 4.5 peak sun hours as the figure for our example.

Finally, pick a solar panel power rating

The final variable is how much electricity each solar panel can produce per peak sun hour. This is called power rating and it’s measured in Watts.

Solar panel power ratings range from 250W to 450W. Based on solar.com sales data, 400W is by far the most popular power rating and provides a great balance of output and Price Per Watt (PPW).

If you have limited roof space, you may consider a higher power rating to use less panels. If you want to spend less per panel, you may consider a lower wattage. Everybody has different goals, and you should feel free to choose the panels that best suit your needs.

For the purposes of our example scenario, we’ll use 400W panels.

Related reading: How To Choose Solar Panels for Your Home

Calculate how many solar panels it takes to power a house

Now that we have our three variables, we can calculate how many solar panels it takes to power a house.

• Daily electricity consumption: 30 kWh (30,000 Watt-hours)
• Average peak sun hours: 4.5 hours per day
• Average panel wattage: 400W

To solve for the number of solar panels, we can rewrite the equation above like this:

Daily electricity consumption / peak sun hours / panel wattage = number of solar panels

Now let’s plug in our example figures:

30,000 Watt-hours / 4.5 peak sun hours / 400W = 16.66 panels

If we round up, it takes 17 solar panels to power the average American household and meet the goal of 100% electricity offset.

Now since we’re talking national averages, the national average electricity price in the US was 16.7 cents per kilowatt-hour in August 2022. Meanwhile, the average price of electricity from solar systems purchased on solar.com is between 6 and 8 cents per kilowatt-hour.

I’ll let you do the math there.

 

The easy way to find out how many solar panels you need

Now that we’ve gone through the manual calculations of finding out how many solar panels you need to power a house, we’ll show you the easy way. (I know, it’s middle school math class all over again).

Modern home solar projects are planned using satellite technology, and you can start planning your own project using our solar calculator. Simply punch in your address and set your average energy bill to calculate how big your solar system needs to be and how much you can save by switching to solar.

Under the average energy bill slider, the calculator will give you an estimated system size in kW. You can use this number to figure out how many panels you would need.

First, convert kW into Watts by multiplying by 1,000. So 5.2 kW would be 5,200 W.

Next divide the total system size in Watts by the power rating of the panels you’d prefer. If we use 400W, that would mean you need 13 solar panels.

System size (5,200 Watts) / Panel power rating (400 Watts) = 13 panels

Of course, the easiest way to know how many solar panels you need is to team up with an Energy Advisor to design a custom system.

Frequently asked questions

How many solar panels does it take to power a house?

Based on average electricity consumption and peak sun hours, it takes around 17 400-Watt solar panels to power a home. However, this number will vary between 13-19 based on how much sun the panels get and how much electricity the home uses.

Use the equation below to get an estimate of how many solar panels you need to power a house.

Daily electricity consumption / peak sun hours / panel wattage = number of solar panels

Can I run my house on solar only?

Absolutely. By pairing solar panels with battery storage, it is very possible to run a house on solar power alone. And in many areas it’s cheaper than paying for electricity through a local utility.

Without battery storage, you can still offset your grid electricity use with solar panels through net metering and eliminate your electricity bill. You will still be using grid electricity when solar generation is down, but you will only pay for your solar equipment.

Is 10 kW enough to run a house?

Yes, in many cases a 10 kW solar system is more than enough to power a house. The average US household uses around 30 kWh of electricity per day, which would require 5 kW to 8.5 kW solar system (depending on sun exposure) to offset 100%.

 

How Many Solar Panels Do I Need?

The average American home needs between 15 and 19 solar panels based on the average electricity usage of 893 kilowatt-hours (kWh) per month. Installing that many solar panels would cost between $12,000 and $17,000 after the federal solar tax credit. 

But, chances are your energy usage doesn’t line up exactly with the U.S. average, plus the number of solar panels you need depends on several other factors, like the location of your home and what kind of solar panels you choose. 

So how exactly do you figure out how many solar panels you need? We’ve got you covered. 

Calculate how many solar panels you will need to power your specific home

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Key takeaways

• The average home in the U.S needs between 15 and 19 solar panels to cover its electric bills.
• Three main factors impact how many solar panels you need: your energy usage, the sunlight in your area, and the solar panels you choose.
• An average solar energy system will require between 260 and 340 square feet of roof space.
• If you have limited roof space, high-efficiency solar panels let you install fewer modules while still covering your energy needs.

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Factors that determine how many solar panels you need

You may think that the size of your house determines how many solar panels you need, but it doesn’t! To really understand how many solar panels your solar energy system needs, you need to determine the following: 

• Your energy usage: The more electricity you use, the more solar panels you need to cover your electricity costs.
• Sunlight in your area: Homes in areas that receive less sunlight will need more solar panels to eliminate their electricity bills than those in sunnier states. As a rule of thumb, the southwestern United States gets the most sun in the country, while the northeast gets the least.
• Panel wattage: The wattage of the solar panels you choose, also called the power rating, determines how much energy the panels will produce and most solar panels installed today have a power rating of about 370 watts per panel; fewer panels are needed when you install panels with high wattage ratings. 

Below, solar expert and SolarReviews Founder Andy Sendy, breaks down everything you need to know about how many solar panels you need to power your home.

 

How to calculate the number of solar panels you need

Our solar panel cost and savings calculator is the fastest, easiest, and most accurate way to find out how many solar panels your home needs - and you don’t have to do any math. Plus, we’ll give you the average cost of a solar installation for your specific home and how much it’ll save you on your electric bills.

However, if you want to put pen to paper and work out the calculations for yourself, follow these four easy steps to find how many solar panels you need. 

Step 1: Determine your energy usage 

Check out your most recent power bill to see your monthly electricity consumption. In most cases, the total amount of electricity used will be shown at the bottom of the bill in kilowatt-hours (kWh).

Your yearly energy usage will give you the best estimate for how many solar panels you need, as energy usage fluctuates in different seasons (think about how much electricity you use for air conditioning in the summer!). 

Because monthly energy usage varies so much, it can be beneficial to dig up your monthly electric bills for the past year, add the electric usage together, and divide by 12. 

But using just one utility bill to find your energy consumption is still enough for a ballpark estimate. 

Step 2: Find how much energy solar panels produce in your area 

Now that you know how much electricity your home uses in a month, you need to find the amount of sunlight your area receives. This is usually measured in something called "peak sun hours", which is essentially the intensity of sunlight in your area. 

We have a complete list of the average number of daily peak sun hours for each state. This is how much sunlight your area receives daily, be we need to know how much you receive monthly. To do this, simply multiply your state’s daily peak sun hours by 30. On average, the U.S. receives between 120 and 150 peak sun hours per month.

The monthly peak sun hours you get tells you how many kilowatt-hours of electricity 1 kilowatt (kW) of solar panels will produce in your area in one month. So, if your state receives 150 monthly peak sunlight hours, 1 kW of solar will produce 150 kWh of electricity per month.

Step 3: Calculate solar system size you need 

Since you now know how much 1 kW of solar will produce in your area, you can determine what size solar system you need to cover your electricity needs. 

Divide your monthly electricity usage by the monthly peak sun hours in your area to find the system size you need in kW. For the average home in the U.S. the calculation would look something like this:

893 kWh consumed / 135 monthly peak sun hours = 6.61 kW of solar

Step 4: Figure out how many solar panels you need 

So, you know the size of the solar system you need to cover your energy usage. Now what? To figure out how many solar panels you’ll need, take the solar system size and multiply it by 1,000 to convert the size from kilowatts to watts. Let’s use the same example as before: 

6.61 kW of solar x 1,000 = 6,610 watts of solar

Next, take the size of the system in watts and divide it by the wattage of the solar panels you want to install. The average solar panel in the U.S. is about 370 watts in size. For the sake of our example, that means you would need 18 solar panels to cover your energy usage.

6,610 watts of solar / 370-watt solar panel = 18 solar panels

Voila! That’s the number of solar panels you will need to power your home.

How much roof space is needed for solar panels?

The average solar installation will require between 260 and 340 square feet of roof space. To find out how much roof space your solar system needs, just multiply the number of panels you need by 17.55 square feet, which is the area of most residential solar panels sold today. 

If you have limited roof space, you may need to get high-efficiency panels, or panels with a higher power output so you can install fewer panels while still covering your energy needs.

Average number of solar panels needed based on system size

The table below shows how many solar panels you need based on the size of the system, as well as an estimate of the amount of power the solar array will produce.

Table 1. Number of panels and roof space required based on system size System size Estimated monthly energy production Number of panels* Approx. roof space required 4 kW 480 - 600 kWh 10 176 sq. feet 6 kW 720 - 900 kWh 15 264 sq. feet 8 kW 960 - 1,200 kWh 20 351 sq. feet 10 kW 1,200 - 1,500 kWh 25 439 sq. feet 12 kW 1,440 - 1,800 kWh 30 527 sq. feet 14 kW 1,680 - 2,100 kWh 35 615 sq. feet

*Assumes 400-watt panels

Do solar panels make sense for my home?

Some factors, like roof direction, roof shading, the solar inverter you choose, and whether or not you’re including a solar battery could also influence the number of panels you need. These factors, however, are hard to quantify on your own. 

The best way to determine the ideal location for your home solar power system and how many solar panels you need is by getting quotes from qualified local solar companies. Solar installers will also be able to give you an idea of the upfront costs of solar for your home and what rebates, incentives, and tax credits homeowners in your area qualify for.  

In the meantime, using the steps in this article can give you a rough estimate of how many photovoltaic solar panels you need to power your home with clean, renewable energy. 

Calculate how quickly a solar installation would pay for itself after rebates

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How Many Solar Panels Are Needed to Run a House? (The Answer Will Surprise You!)

Are you thinking about adding solar to your home? With over 2 million homes in the United States with solar now, many homeowners are recognizing how beneficial they are. If you’re considering having solar panels installed in your home and not sure where to start, then you’ve come to the right place.

We’re going to go over the details of how solar panels work and how many you might need for your home.

Let’s take a look.

How Do Solar Panels Work?

Simply put, solar panels absorb photons that then tap electrons free. Once they’re free from the atoms, it creates electricity! Solar panels take in light and directly turns it into a flow of electricity to use.

• Solar panel cells absorb sunlight
• They convert the light into DC power.
• All systems need some type of inverter (string, Micro or hybrid) to convert that power to AC power.
• The electricity is then sent through wires into your home
• That powers everything connected to it
• Any excess of electricity produced is then fed into the electric grid

Solar systems are not complicated and easy to understand once you have the basics down. Now that you understand how they work, let’s take a look at how long they last –

How Long Do Solar Panels Last?

In short, a quality solar panel can last up to 25 years or even longer. Solar panels are designed to live a long life in the elements outside.

Your typical solar panels come with a warranty that lasts 25 years, so you are guaranteed to reap the benefits for quite a long time.

According to a study conducted by the National Renewable Energy Laboratory, solar panels last 80% longer than their warranty.

This can save you thousands on utility bills down the road!

How many Solar Panels Do You Need?

To find out how many solar panels you’ll need for your home, you need to consider everything that uses power. Taking a look at your utility bill can also give you a good idea of how many you might need.

How Many Watts Do You Use?

When looking at your utility bill, you should be able to see kilowatt-hours (KWH). KWH for homes can vary greatly depending on location. A home in the south is more likely to draw massive amounts of energy from air conditioner units.

Finding the average daily energy usage will help you calculate your solar needs. Once you have your usage you can look at how much wattage you’ll need to be able to run everything.

Peak Sunlight Hours

Keep in mind that solar panels only work when they are in direct sunlight. After the sun is no longer shining down on them, they aren’t producing energy. Peak sunlight hours are when your panels are in direct sunlight.

Depending on your location, your peak sunlight hours can vary.

Multiply your home’s hourly energy usage by the peak sunlight hours your home has and then divide that by a solar panel’s wattage. You can do this both high and low wattage panels to find a range of what you might need.

Most reputable solar companies can also help you determine this by providing them with this basic information as well!

Solar Panels For a 1500 Square Foot House

The average home in the United States is roughly 1500 square feet. With a home of this size, the typical electric bill comes in around $100 month. In order to cover the electricity for this home, you would need an estimated 15-18 solar panels.

For example, a typical fridge may be rated for 250 watts and runs for 4 hours a day. 250 watts X 4 = 1000W. A 1k watt is equal to 1 kWh of energy in a day.

This, of course, is a general estimate and eclectic usage, sunlight hours, location, and the type of panels can change this amount.

Types of Solar Panel Systems

When it comes to solar panel systems, there are three different types. Gid-tied, grid-tied with battery backup, and off-grid. Let’s take a look at each one.

Grid-Tied System

The most popular type of system used by residential houses is the grid-tied system. This type of system is tired directly to your home and the utility grid. This allows homeowners to seamless switch between power from either the solar system or the utility system.

If the system produces more power then the house needs, the excess power will be sold back to the utility company or it will be used to prorate your bill.

These are generally the cheaper systems out of the three.

Grid-Tied With Battery Backup

Similar to the grid-tied system, this solar power system is also connected to both your house and the utility grid. However, it also comes equipped with a battery bank.

When the panels produce electricity while in direct sun, it stores any excess power in its battery banks. This power can then be used at a later time after the sun has gone down and the panels are no longer producing power.

The power can also be sold back to the utility companies as well – This system is much more expensive though because of the expensive price of batteries.

Off-Grid System

Unlike the other two, the off-grid system is not connected to the utility grid at all. This system is only connected to your home and a battery bank. The battery bank is essential in this setup in order to continue producing power for your home 24 hours a day.

This tends to be the most expensive system because you need an excessive amount of battery in order to store the amount of energy your house will need.

How Much Do Solar Panels Cost?

Solar energy has become cost-effective most recently. The prices have gone down and they are much more available to the public. The average cost of a solar panel is almost less then half it was a decade ago.

A typical solar panel can run between 50 cents to 70 cents per watt. At 50 cents a watt, a 350W panel would cost $175. In a typical home needing 15 solar panels, the total cost for panels would be $2,625.

That is for the panels alone though, the cost of installation needs to be considered as well. It takes professional that know what they are doing to properly install a solar system in your home.

How Much Does a Solar Installation Cost?

This can vary depending on the company, but for an average installation, it can run you between $15,000 and $30,000.

Many solar companies offer incentives and financing. There are a ton of other financial benefits that come along with installing your home:

• Electricity rates have risen across the nation and are higher now than they have ever been
• You can save thousands on electricity bills and will only continue to save more over time
• The resale value of your home skyrockets. Many home buyers now are searching for homes that come with a solar system already installed
• The government offers a massive tax credit when it comes to solar systems. Some states also offer a rebate program
• The systems come with a warranty that secures your investment for at least 25 years

How Much Does it Cost Total For a 1500 Square Foot House?

The typical 1500 square foot house can use around a 6kw  solar panel system. The total cost of the panels and full installation can be estimated at about $18000.

To get an estimate for your home and how much you can save, contact a local energy consultant. They can provide you with an installation quote and answer any questions you have about solar systems for your home.

Things to Keep In Mind

Solar panels are a great way to save money and go green. However, they only work effectively when using the correct products and proper installation.

You want to make sure to only use quality solar panels and solar equipment. Using cheap or knock-off brands won’t produce as much as quality products.

Ensuring proper installation is key to a solar system. Not having it properly installed can cause ineffective panels, failure, or fires. Make sure to always have a Professional company conduct the install for your home.

Wrapping Up

Now that you have an in-depth understanding of how solar panels work and how many you’re going to need, Its time to go green and start saving money. Contact a professional solar company and receive a quote to have your solar system installed for your home.

If you have further questions about solar panels or are ready to get them installed for your home, send us a message today.