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how many solar panels do I need

How Many Solar Panels Do I Need?

Aside from costs, it’s about the most common question people have when going solar. How many solar panels do I need?

Below you’ll find everything you need to figure out how many panels you’ll need to power your home.

How Many Do You Need vs. How Many Can You Get?

One quick thing first. There may be a difference between how many panels you “need” vs how many you can get. 

Let’s say you go through the info below and calculate you need 10 panels for your home. But, due to the size of your roof or your budget or some other factor, maybe you can only get 5. 

To figure out how many you can get, you really need to have a local installer come by and assess your specific situation. To figure out how many you need to produce the power you need for your home, check out the information below!

Things That Impact How Many Solar Panels You Need

There are a lot of factors that go into figuring out how many panels you’ll need. Some of the key ones are:

  • The type of solar panel you get and its efficiency
  • What type of roof you have
  • The angle of your roof
  • How much direct sunlight your roof gets each day
  • Where you live
  • Available roof space for solar panels

These things will vary depending on your situation. However, there are some things you need to know to figure out how many solar panels you need no matter what your situation. Let’s look at those next.

What Are Your Goals?

Your goals for going solar will be a big factor in figuring out how many panels you need.

Do you just want to lower your electric bills? Are you wanting to increase the value of your home? Is the most important thing to you reducing your carbon footprint? Do you want to go totally off-grid and produce all your own electricity?

Your answers here will help you figure out how much solar you need.

Calculate How Much Energy You Use

When you want to figure out how much energy you’ll need your solar panels to produce, you’ll need to know how much energy you use.

The easiest way to do that is to look at your monthly electric bill. On your bill, it should show how much energy in Kilowatt Hours (kWh) you use each month. Many electric bills will have a chart to show how many kWhs you’ve used each month. 

If not, you can take your monthly usage and multiply it by 12. Or daily usage and multiply by 365. 

That number may not be 100% accurate, however, since electric consumption will vary month to month. For example, you’ll use a lot more electricity in July when your AC is pumping compared to February.

In any case, find out how much electricity you use each year to give you a clear idea of what you’ll need your solar panels to produce.

Also, think about any changes you may have in your electricity usage. For example, if you are planning to get an electric car, that may significantly increase your electric demands.

Calculate Your Average Direct Sunlight Per Day

To figure out how much solar you’ll need, you’ll have to know the average amount of sunlight your roof gets per day. You can find some helpful resources and maps here.

For example, Los Angeles gets around 5 hours a day of peak, direct sunlight on average.

Keep in mind that trees blocking your roof and other factors will affect this for your home.

Calculate Your Solar System Size

There are two key numbers you need here to figure out the size of the solar installation you’ll need. They are the average sunlight per day and your monthly energy usage in kWh.

Once you have those, here’s the math you’ll need to calculate your solar needs.

kWh per month usage / (30.5 * average sunlight per day) = kW 

So if you use 1000kWh per month and live in Los Angeles, here’s what that looks like…

1000 / (30.5 * 5) = 6.56 kW

So 6.56 kW is what your solar installation will need to produce all the energy you need to power your home.

How Many Solar Panels Do I Need?

Okay, time to circle back to that original question of how many solar panels you’ll need.

Once you have the size of the system calculated there’s just one more step to figuring out how many panels you’ll need.

First, you want to take the number of Watts needed. To get this, multiply your system size by 1000. So, using our example above, we’d multiply 6.56 kW by 1000 to get 6,560 Watts.

Then you’ll need to know the wattage of the solar panels you’re going to get. On average, panels on the market today range between 340 and 400 Watts.

If we split the difference and say 370 Watts, then you divide 6,560 by 370 and end up needing 18 (rounded up from 17.73) solar panels to produce all the energy for your home.

Bottom Line

Again, that’s 18 solar panels if you want to produce ALL the energy you’ll need. You can get away with fewer if you just want to lower your electric bills and/or carbon footprint.

The above gives you a rough idea of how many solar panels you’ll need. However, there are a lot of factors at play here. Your best bet to get the most accurate number is to get an expert to help. You can find local solar installers near you in our free solar installer listings.