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

Are you looking for a way to reduce electricity bills and contribute to reducing global warming for your family? Solar installation is an imperative addition to the future of American homes.

It is expected that by 2024, 2.5% of all American homes will have solar installation. According to the Solar Energy Industries Association, the USA has already surpassed the whopping number of 2 million solar PV installations. It’s a great sign of growth in the renewable energy sector.

If you’re thinking of getting your hands on this nifty little product, keep reading. You’ll find out how many solar panels run a house, whether it’s 1500, 2500, or 3000 square feet. We’ll also cover the cost of solar panel installation.


You will need between 15 and 20 solar panels to run a 1,500-square-foot home, and they’ll cost you roughly $2625 – $3675. You will need between 37 solar panels to run a 2,500-square-foot home, and they’ll cost you roughly $2975-$6,600. You will need between 44 solar panels to run a 3,000 square foot home, and they’ll cost you roughly $7700.

In this article, we’ll also cover the following:

  • How long do they last?
  • What happens with surplus energy

Table of Contents

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house with solar panels

How Many Solar Panels Do You Need?

The number of solar panels you need for a house depends on the size, although the number is usually between 15 and 40.

1,500 Square Foot

An average American home is approximately this size. Thus we can get a rough idea of how many panels you require. On average, a house this size generates a bill of around $100 per month.

For usage of this size, you would require somewhere between 15 and 20 panels. The exact figure can be determined when you know the other factors like usage and sunlight hours. Consider the wattage of each brand.

solar panels on a roof

2,500 Square Foot

A house of this size means even more electricity is needed. Therefore it’s more common for a house this size to use both generic and solar-generated electricity. A place of 2500 sq feet generates approximately 11,775kWh per year.

This figure divided by the average wattage generated by most brands’ panels comes down to around 37 panels. That’s if you choose to rely on solar alone and no other source of energy. For example, if you switch up to regular utility company power in the winter, the number will decrease.

3,000 Square Foot

A house of this size will generate almost 14000 kWh per year. This usage generates around 44 panels on the roof if you only want solar energy to run in the house. Keep reading further below to find out the cost of these installations.

Let’s cover the basics and information homeowners need to get you the right solar system. It’s a great way to lower your utility bill!

How much will it cost?

Now that we’ve seen the number needed, we can look at the money factor.

1500 sq. foot cost

Since the use of solar began initially, the prices of their usage have gone down significantly. A typical one can cost between 50 to 70 cents per watt. A 350W model would then be anywhere between $175 and $245. Since we mentioned that a house of this size would require about 15- 18 panels, it comes down to $2625 – $3675.

2500 sq. foot cost

You would require anywhere between 17 to 25 premium panels with high efficiency for a home of this size. A 2500 square foot-size home would generate around 11,775 kWh per year.

If you’re using budget ones, the number needed will go up. According to the calculations we just performed above, your cost would come to $2975- $4550. The lower range reflects 17, and the high range reflects 26 panels.

3000 sq. foot cost

You would need no less than 44 panels for a huge home of this size. This size will generate around 14130 kWh per year. The cost would come down to $7700 of using the panels at 50 cents per watt.

Note: Here, the installation cost has not been included. When added, it will significantly increase your spending. The cost of installation varies from company to company.

Even if you don’t get a system size that covers the overall utility bills, you can, of course, still save money and cover some of your electricity needs.

When you have additional questions, get in touch with an installer that makes sure to help you out. Some provide ballpark estimates, and others provide quotes. It depends on various variables, including the condition of your roof.

Figure out your home’s energy needs. The typical solar panel wattage capacity is upward of 400W per panel, and excess power can be sent back into the utility grid.

solar panels on an old home

How do they work?

What goes behind the working of those shimmery panels that eventually result in the production of electric current? The panel contains a layer of silicon, a metal frame, and wiring. All of this is encompassed within a glass casing with film. This equipment comes together to make a semiconductor. The cells within these are called photovoltaic cells.

This is how it goes down. The sunlight hits the panels, and the cells are charged. Electrons are released from the semiconductor wafer, and their motion creates an electric current.

Now that the electricity is ready, it needs a way to power the home you live in. But your house operates on Alternative current (AC) and not the Direct current(DC) produced by the panel. This is why an inverter is brought in to convert the DC to AC and start powering your needs.

They can be a great power source if your family lives near the beach!

Square feetNumber of solar panels needed
1,50015 – 20

What happens to surplus energy?

A net meter records usage in your home. There may be rainy days where solar energy is low and days when you’re not home. Enough solar energy is generated to run your home on regular days.

The meter will track this energy usage coming from and to your place. This makes it easy for the utility company to give you credits for days away, and surplus energy flows into the grid.

How long do they last?

They have started booming. The innovation of solar panels is noticed to have lasted about 25-30 years before it needs replacing again. However, some systems are known to last about 50 years too! You might be surprised at these figures. It is because solar panels require little to no maintenance that they can last almost the life of an average human.

solar panels on a house

Do they lose efficiency over time?

Yes, most solar panel systems degrade at about 1% per year. That means after 10 years. They would have lost about 10% of efficiency.

By the time the lifespan of a solar panel ends, they would still be working at about 75% efficiency. It is not bad at all!

alternative energy source

How many do you need?

Naturally, the number of solar panels needed increases with the size of your house. But there are also other factors to consider. Keep reading to find out all the pointers:

  • Sunlight hours: Depending on the location of your home, peak and brightest sunlight hours will change. You will have to keep track of the light in your home and calculate it according to the voltage used by your family. Your hourly usage is multiplied by the sunlight hours at peak time. The resultant figure will be divided by the wattage of the panel.
  • Your usage: You will have to keep track of your usage to determine how many you will end up with. This can be done easily by taking a look at your utility bill and checking the kilowatt-hours (KWH). Some families will draw more energy due to several factors. For example, hot weather forces air conditioners to be used more frequently and hence a higher bill. Ones that have a workshop or a small business are likely to have more appliances that will need even more current.
  • The size of the property: It’s natural that with a bigger house, you’ll require more plug points and thus more current to power them. Therefore, the number is likely to increase with the square foot area. Let’s take a look at the area-wise allotment of panels below.
Number of solar panelsWatts generated, low endWatts generated, high end

How many kilowatts does my family use?

By now, you’re probably convinced about the idea of installing solar in your home to save on bills and aid climate change. You’re probably wondering, how many solar panels does your home need? You need to know how much electricity your house uses to answer this.

Take a look at your past bills. Divide the monthly average by thirty or the yearly average in kWh by 365. The resultant factor should be divided by 24 to determine your hourly average electricity usage. Your answer will be in kWh.

Alternatively, you can also go the detailed route and take note of the wattage of each device you own and use. You can find the wattage on each device and multiply it by the hours it’s plugged in to get the kilowatt requirements.

For instance, 100 watts for a device plugged in for 10 hours will equal 1000 watt-hours or 1kWh.

In this manner, you can calculate all the device hours and find the charge per kWh to find the expense of your home approximately.

solar panels at night


Let’s get into the details of what type you might install and how the types differ from each other. The basic three types of solar panels are listed below.

1. Thin film

This type is made from many types of materials, but the most commonly used is cadmium telluride (CdTe). This layer of CdTe is placed between transparent layers. They help capture sunlight and even have a glass layer on top for protection.

The advantage that this type offers over others is its flexibility and portability. However, they offer lower performance than their supplements.

2. Monocrystalline

These are made from silicon sheets and are the purest solar panels. Since the silicon is so pure, it is responsible for the highest efficiency of all types. The newest ones go as high as 20% in terms of efficiency.

They also last the longest and occupy the least amount of space. This also means they cost the highest, and you’re going to have to dig up some savings to invest in this one.

3. Polycrystalline

This type has a blue speckled look and has squares. They are made from melting raw silicon and don’t have a long manufacturing process like monocrystalline. It makes them cheaper.

For this reason, it also has a lower efficiency rate and shorter lifespan. Their efficiency is about 15%. They can be quite affected by high temperatures, which isn’t the case in monocrystalline. Polycrystalline also occupies more space than previous types. However, power outputs are usually the same when it comes to both.

How many panels does it take?

As we mentioned before, the number of solar panels you need depends on 2-3 factors. An average home is about 1500 square feet in the US. If we run by the average scenario, a home of this size usually clocks about $100 in its utility bill.

That means you would need around 15-18 panels to cover a home of this size for solar installation. This figure will differ based on your peak sunlight hours and location. Hourly usage will also influence it. For a bigger house, the panel number just keeps increasing.

Solar being installed

Have you decided which of the following types you’re going for?

  • Thin film
  • Monocrystalline
  • Polycrystalline

With various incentives and tax credit, there’s no reason any household in a sunny place like California or Arizona shouldn’t have such a system! Look into the programs offered where you live, as different states have different programs they offer. Despite having less sun than in Texas, people are also installing these panels in places like Massachusetts and the North East of the United States.

That’s it, folks!

We hope this article has increased your knowledge about the possibilities of renewable energy. Hopefully, you can cash in on the savings it can also generate for you. The more people hop on to the solar train, the less expensive it’ll be to install various solutions and reach grid parity.

Whether it’s partial or complete solar power, this is the perfect contribution to reducing climate change and greenhouse gases. Get your hands on any of these bad boys, save money and go green – forever!

Do the math and look at the numbers. You can find an online calculator that can figure out your energy consumption and how long it will take for the system to repay itself. We hope this guide helped you! It makes a lot of sense with all the benefits.

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