What’s the Average Household Solar System Size?

When making a decision on whether or not to go solar, many customers wonder how many solar panels their system needs to have. They heard from one neighbor that they got 10 panels, but they also heard that their uncle had 40 installed! The discrepancies in system size can leave many homeowners unsure as to what the right decision is when it comes to their own homes. When planning the size of a solar energy system, it is important to look at many different factors.

How Many Solar Panels Do I Need?

The number of panels you need for your house depends on factors like location, electric consumption, sunlight exposure and panel performance. An average homeowner needs 15 to 20 solar panels to fully offset their electricity bill with solar.

To know exactly how many panels your home needs, get a customized solar quote from Pineapple Energy

How Much Energy Do I Use?

When you are planning the size of a solar energy system, you want the system’s production to match the electrical usage that the home is already using. A typical American single family home uses about 10,400 kWh (kilowatt-hours) in a single year. That means you want the solar energy for that home to produce 10,400 kWh or more to offset your utility bill. Most panels used in the residential solar industry are sized between 350-450 Watts, and in ideal conditions, 17 – 400-watt panels would produce enough energy to cover the average American’s usage. ​

Calculating How Many Solar Panels You Need

To calculate how many solar panels your home needs, you need to know how much energy your household uses, your roof’s usable space, the climate and peak sunlight in your area. Experts recommend adding a 25% “cushion” to your yearly production to ensure you can generate all the clean energy you need, but to keep the math simple we will model this example on 100% of your electric offset.

*System size in kWh/production ratio/watts of panel = number of panels

Your electric usage is measured in kWh. It is best to have a full year of kWh usage when calculating your solar needs. The average U.S. home uses about 900 kWh per month.

Production ratio is based on how much sun your panels will get which is largely influenced by your location and the season. Closer to the equator and more sun will have a higher production ratio than a climate without much sun. Average production ratios are between 1.3 (more sun) and 1.6 (less sun).

Production of solar panels is measured in watts (1,000 watts = 1 KW). The average wattage in panels we currently use is 400 watts.

10,400kWh/1.5/400w = 17.33 Panels

To cover 100% of your usage you would need at least 17 panels with little to no shading. But there are other factors that you still need to consider.

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How Much Does the Shape of My Roof Matter?

In short, a lot! Solar panels on average are about 3×5 feet in size and depending on how much energy you need them to produce, you might need 20 panels, that’s 300 square feet of solar panels that need to fit on your roof. Along with the space you need, you also need to look at what direction your roof is oriented. A true southern-facing roof plane is the ideal spot to install panels in North America. If your roof only has space for panels on a plane that is facing a different direction, solar can still be a good option, you just may need to add additional panels to make up for lost hours of solar production. An expert solar installer will assess your roof to optimize the placement of panels.

Is My Location Good for Solar?

The Southwestern region of the United States is the best place in the country for solar panels, but that doesn’t mean you shouldn’t consider it if you live in the North. With the advancements in solar panel efficiency that have been made over the past decade, solar has become a great option even for areas that receive less solar hours on average. When comparing homes in Minnesota and California that have similar energy usage, the homes in Minnesota on average only need five or six more panels.

So How Many Panels Do I Need?

Using the information above, you may be able to get a pretty good idea of what your solar energy system size needs to be. But to be certain, we recommend that you talk to one of our solar experts at Pineapple Energy to get the most accurate system size.

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