Solar Energy Systems: How to Calculate Available Roof Space

A home solar energy system can create enough electricity to meet your household needs — if the system is sized correctly.

An online calculator can give you an estimate of how many solar panels you’ll need to harness an ample supply of energy from the sun. However, it won’t tell you whether your rooftop has sufficient space to hold that number of PV modules.

Solar Energy Systems How to Calculate Available Roof Space

So how can you tell if your roof can handle an appropriately sized solar energy system?
Your best resource for information is a local professional photovoltaic contractor, such as the experts at Intermountain Wind & Solar.

But to get a general idea, you can use the handy guide below.

How Much Open Roof Space Do You Have for a Solar Energy System?

If you want an exact calculation of your available roof space, you could climb up and measure all the open areas.

If you’re not a fan of that plan, don’t worry. Google’s Project Sunroof website can easily take care of the calculations for you. Type in your address, and the online tool will use high-resolution satellite imagery, along with the computing power of Google Maps, to determine how many square feet of rooftop space you have available for a home solar energy system.

How Many Solar Panels Will Fit in that Space?

Let’s say the Project Sunroof tool measures 285 square feet of available rooftop space on your home. How does that help you figure out if you can install the necessary number of solar panels?

PV modules, on average, measure about 3 feet by 5 feet. That means each one needs about 15 square feet of space.

If you take your amount of open roof space and divide by 15, you’ll find out approximately how many solar panels will fit. In our example, this works out to be 19.

285 square feet ÷ 15 square feet = space for 19 solar panels

What if You Need More Home Solar Power?

After reviewing your options for solar panels, let’s say you’re leaning toward installing 285-watt PV modules. Continuing our example, how much electricity will 19 of them produce? Will it be enough?

A bit of easy math can tell you the answer. First, since home solar energy systems are measured in kilowatts, you’ll need to divide that 285 watts by 1,000. That tells you that each photovoltaic module will produce 0.285 kW of electricity.

Now, multiply that number by 19, and you’ll find the total power production.

0.285 kW × 19 = 5.415 kW

In this scenario, your rooftop can hold a 5.415 kW home solar energy system. But what if that’s not enough to meet your household energy needs?

You could try reducing your electricity consumption. An online or professional home energy audit can provide suggestions for making your home more energy-efficient. If you’d rather not make any changes to your lifestyle, you may want to consider installing ground-mounted PV modules instead of (or in addition to) a rooftop solar energy system.

The best way to determine exactly how much photovoltaic energy you can produce at your home is to talk to a professional solar installation contractor. The team at Intermountain Wind & Solar can design and install a cost-effective photovoltaic array to power your Utah, Idaho, Colorado, Nevada or Wyoming home. To discuss your home solar energy system options, contact us for a free consultation today.