Factors that determine how many solar panels you need

To really understand how many solar panels your solar energy system needs, you need to know 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.

How to calculate the number of solar panels you need

Figuring out how many solar panels you need is easier than you think. Once you know how much energy you use and the amount of sunlight you get, you can get a good idea of the number of solar panels to put on your roof.

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).

Step 2: See how much sunlight your home gets

Now that you know how much electricity your home uses in a month, you need to find the amount of sunlight your area receives. How much sunlight an area gets is measured in peak sun hours, which represents the intensity of sunlight at a given location.

Step 3: Find out how much energy solar panels produce near you

Use how many peak sun hours you get to determine how many kilowatt-hours of electricity a solar panel can produce in your area. 

Take the size of a solar panel in watts and multiply it by the number of peak sun hours you get in a month to see how much electricity a solar panel in your area will produce monthly. You’ll have to convert this from watt-hours to kilowatt-hours by dividing it by 1,000 to match your energy consumption from your electricity bills. 

Step 4: Calculate how many solar panels you need

Now you know how much energy you’ve consumed and how much energy a solar panel can produce where you live, you’re ready to figure out how many solar panels you need.

All you need to do is divide your energy usage by the amount of solar energy generated by one solar panel. This will tell you how many solar panels you need to install to generate that much electricity.

Do solar panels make sense for my home?

Solar panels are a great investment for many homeowners and can often significantly reduce or even eliminate monthly electricity costs.

The best way to determine how many solar panels you need to lower your utility bill is by getting quotes from qualified local solar companies. Solar installers can look at your home's characteristics and determine exactly how many panels you need and how much they can save you.