Updated 3 days ago

How much energy does a solar panel produce?

Find out how much energy solar panels can produce on your roof

On average, a solar panel will produce about 2 kilowatt-hours (kWh) of electricity daily. That’s worth an average of $0.36. Most homes install around 15 solar panels, producing an average of 30 kWh of solar energy daily. That’s enough to cover most, if not all, of a typical home’s energy consumption.

There are a few factors that will impact how much energy a solar panel can generate, including available sunlight, the panel’s characteristics, where it’s installed, and its age. You can watch solar expert Ben Zientara break down how much electricity solar panels produce in this video:

Calculate how quickly solar panels on your home would pay for themselves

What is the power output of a solar panel?

Most solar panels installed today have an output of 370 to 400 watts of power per hour in ideal conditions. Commercial and utility-scale installations use more powerful 500-watt solar panels. The output of a solar panel is often referred to as the solar panel’s size.

Here are the power ratings offered by the best solar panel brands on the market:

Brand

Model

Max. output

Qcells

Q.TRON BLK M-G2+ SERIES

430 W

Silfab Solar

SIL-430 QD

430 W

JA Solar

JAM54S30 LR

440 W

Jinko Solar

Eagle 54 G6R

440 W

Unfortunately, your roof isn’t a lab, so the solar panels will likely produce less power than they’re rated for in the real world. But solar systems are designed with this in mind, so they will produce the amount of power your home needs!

How much energy does a solar panel produce?

Time

1 day

1 week

1 month

1 year

Energy produced

2 kWh

14 kWh

60 kWh

730 kWh

Energy is the amount of power a solar panel produces over time. On average, a solar panel will generate about 2 kWh of energy each day.

One solar panel produces enough energy to run a few small appliances. To put it in perspective, energy generated by one panel in one day could run your TV for 24 straight hours!

Chances are you’re not going to install just one solar panel. Most homeowners install between 15 and 19 solar panels to cover their electricity needs. An average 6 kW solar installation will generate 915 kWh of electricity per month.

How much energy will solar panels generate on your roof?

4 factors that affect the amount of electricity that solar panels produce

Graphic displaying the four factors that impact how much energy a solar panel produces: 1. The amount of sunlight 2. Panel and system characteristics 3. Your roof 4. The panel's age

We want to be totally honest with you: most of the time, solar panels won’t produce the maximum amount of energy possible. Solar panel specifications, like power output ratings, are determined by testing the panels in a laboratory under Standard Test Conditions.

Four main things will impact how much energy your solar panels will produce:

  1. The amount of sunlight

  2. Panel and system characteristics

  3. Your roof

  4. The panel’s age

1. Amount of sunlight

A map displaying the average daily peak sun hours of each state in the U.S using data from The National Renewable Energy Laboratory

The amount of sunlight that hits a solar panel is one of the biggest factors in how much electricity it will generate. The more sunlight available to the panel, the more electricity it can produce.

Solar panels installed in sunnier states will generate more electricity than those in more overcast areas. But, solar panels do still generate electricity in cloudy weather, just not as much!

We use peak sun hours to measure how much direct sunlight a location gets per day. Arizona, for example, receives 7.5 peak sun hours each day, while Alaska only gets 2.5. So, a 400-watt panel in Arizona can generate 3 kWh in a day versus just 1 kWh in Alaska.

2. Panel characteristics

The panel itself also affects how much energy it can produce. Solar panels are made up of solar cells, which are what actually turn sunlight into electricity. 

There are different types of solar panels: monocrystalline, polycrystalline, and thin-film. Monocrystalline are the most popular because they can generate electricity more efficiently than other types.

The physical size of the solar panel can impact its power generation, too. Solar panels are made up of solar cells. Most residential solar panels have between 60 and 66 cells, while most commercial panels have at least 72 cells. 72-cell panels have more cells, so there is more surface area to turn sunlight into electricity.

How the solar cell is constructed will make a difference, too. Solar panel efficiency has changed over time as new technologies have become commercially viable. Solar cells using PERC technology can generate more energy than traditional cells. There are also half-cut solar cells, where the solar cell is cut in half using a high-precision laser to decrease resistive losses, which increases how much energy the panel can make.

3. Your roof

The characteristics of your roof are a major player in how much energy solar panels can produce for your home. The truth is not all roofs are good for solar. Solar panels should be installed on unshaded roofs and cleared of debris to maximize solar production.

The number one thing you need to consider is the direction of your roof. Solar panels produce the most energy installed on south-facing roofs.

Don’t worry; solar panels can be installed on roofs facing any direction. The panels will just generate less electricity because they get less sunlight.

The following table outlines how much electricity a solar panel will generate facing different directions if all other factors are the same:

Solar panel direction

Estimated output*

South

2 kWh

East

1.7 kWh

West

1.7 kWh

North

1.4 kWh

*Assumes 400-watt solar panel and 5 peak sun hours

4. The panel’s age

The panel’s age is often forgotten, but it’s important to remember that your solar panels won’t produce the same amount of energy for their whole life. As solar panels age, they lose a bit of their ability to generate power. You can think of it as any other electronic you have - your laptop probably doesn’t work as well as it did the day you bought it.

Solar panels, on average, degrade at a rate of about 0.5% per year. So, by the end of a panel’s typical 25-year warranty period, they usually operate at about 85% of what it was initially. Don’t worry – your solar panels will still generate enough electricity to help lower your utility bills.

See how much it would cost to power your home with solar panels

How to determine how much electricity a solar panel can produce

A graphic of the equation to solve how much electricity a solar panel can produce. Multiply the panel's wattage by the peak sun hours to determine the watt-hours of energy produced.

So, now that we’ve covered what impacts a solar panel’s ability to produce electricity, we can get into the good stuff - figuring out how much power solar panels will produce for your home.

We’ve already established that there are a number of factors that are going to impact how your solar panels generate electricity. So, for the sake of simplicity, we’re only going to take a couple of things into account for the below example, including:

  • The wattage of the panel

  • The peak sun hours in your area

All you need to do is multiply the wattage of your panel by the number of daily peak sun hours. 

A homeowner installs a 400-watt solar panel and expects about four peak sun hours in a day. That means this panel would produce 1,600 watt-hours of electricity per day. Electricity is usually measured in kilowatt-hours, so you simply divide your 1,600 watt-hours by 1,000 to get 1.6 kilowatt-hours.

400 watts x 4 peak sun hours = 1,600 watt-hours per day 1,600 watt-hours /1,000 = 1.6 kWh per day 1.6 kWh x 30 days = 48 kWh per month 1.3 kWh x 365 days = 584 kWh per year

Bear in mind this is a simplified way of calculating how much electricity a solar panel produces. The actual amount will fluctuate daily, even hour by hour, based on all the factors mentioned earlier.

Get an accurate estimate of how much energy solar panels will produce on your roof

Power your whole home with solar to save money

Now you know how much solar electricity you can expect one solar panel to produce and how much a whole system can, too.

But the best part is that installing solar does way more than just let you power your home with renewable energy - it helps you save money. By using the electricity generated by solar panels on your roof, you don’t have to take electricity from your utility, which means they don’t have to charge you.

Most of the time, you can install enough solar panels to cover all of your electricity costs. In fact, that 6 kW solar system we discussed earlier could save the average American homeowner around $130 a month!

But of course, this is just an estimate. Just like with how much electricity a panel produces, how much solar panels can save you depends on many factors. The easiest way to determine how much solar panels can save you is by using our solar panel savings calculator below. Not only will you get a free solar savings estimate, but you can also choose to get in contact with vetted local solar installers to start getting real solar quotes for your specific home.

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Written by Catherine Lane Solar Industry Expert

Catherine is the Written Content Manager at SolarReviews, where she has been at the forefront of researching and reporting on the solar industry for five years. She leads a dynamic team in producing informative and engaging content on residential solar to help homeowners make informed decisions about investing in solar panels. Catherine’s expertise has garnered attention from leading industry publications, with her work being featured in Sola...

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