When surveying homeowners, we often hear that ahead of a solar power home improvement project, people are often misinformed about how to determine the right amount of solar panels for their home.

The National Renewable Energy Laboratory created a map showing the concentration of sunlight radiation across southwestern states like California, Nevada, Arizona, New Mexico, Utah, and Colorado. How red is your region? Concentration Solar Resource for Southwestern US. National Renewable Energy Laboratory.

And that’s likely because there isn’t a one-size-fits-all solution. In fact, if anyone is providing that kind of solution, there is likely some underlying assumption or set of assumptions in their calculations. That’s because without a few clear and foundational assertions, it is completely impossible to assess how many solar panels your home requires and, by extension, how much solar energy you need to maintain your normal activities with a much more affordable electric bill.

At Modernize, we highly recommend you contact a professional solar contractor so that they can visit your home and provide a full assessment of what your needs are — translated into solar panel systems and their respective placements — along with a clear breakdown of what you can realistically expect to get as a return on your investment.

But if you want, you can certainly get moving on your own and figure out some of the preliminary information to get you to that point.

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How many solar panels do you need? There’s only one way to confidently answer that question.

When it comes to solar, you should have a solid understanding of the realm of the possible. Acquaint yourself with the amount of solar energy present at your location in the first place.

With that idea in hand, ask yourself some very important questions and write down the answers. These will become essential when you call a contractor and provide preliminary information to get exactly the answer to your bigger questions. While a seasoned contractor will want to visit the house and fully confirm all their data, being able to provide these answers will go a long way to giving you an idea of what your project will look like:

  • What type of roofing do you have?
    • Which way does your roof slant?
    • How big is your roof?
    • What’s its angle?
    • How old is it?
  • How expensive is your electric bill right now?
    • How’s the weather — not climate — in your neighborhood?
    • How much electricity do you use regularly?
    • How much of your electricity is oriented toward HVAC and how much of it toward less demanding devices and appliances?

How many solar panels do you need: Is your roof shaded?

“Ideally, the sun will hit your panels for at least five hours a day,” the Washington Post reports in a short explainer about solar panels. “If trees, hills, or other buildings block the sun from reaching your roof, that’s a problem.”

That’s all very true. A trustworthy contractor will asses your house’s vulnerability to shadows, both present and future, while considering the possibilities of nearby developments growing into the sky or forests pushing treetops into your area. But you can certainly do some of your own homework to determine exactly how much the sun kisses your roof — and how much it will kiss it in the future.

For example, a UC-Berkely National Laboratory team examined on a mass scale when during the day they could expect to find solar panels in shade. They tested Californian cities Sacramento, San Jose, Los Angeles, and San Diego, and determined those time ranges to be:

  • In the morning from 6 to 10 a.m.
  • In the afternoon from 2 to 6 p.m.

On an annual basis, the researchers determined, panels were only affected with a 20-percent decrease at peak shade. Want to know more about your own location and its irradiance properties? Use the Department of Energy’s calculator tool, which asks you for your address and shares the solar energy you can expect.

At Modernize, we frequently speak to homeowners about their home improvement projects. In our recent interviews, 90 percent of homeowners requested a checklist to help them find and vet contractors. Modernize now offers homeowners a free, digital Contractor Checklist as a simple, step-by-step guide to assist with your solar panel project.

How many solar panels do you need: Solar panels don’t have to go on your roof.

While trees, power lines, neighboring structures, and far-away mountains can all cast shadows on your house, the sun’s movement also governs the movement of this shade throughout the day. There are many solar panel installation options at your fingertips, and each will affect the number of solar panels you need to power your house and save on your electric bills.

For the best solar paneling positioning, various technologies track the sun’s movement and react to it. According to the Office of Energy Efficiency & Renewable Energy, “rack mounting is currently the most common method because it is robust, versatile, and easy to construct and install.” Solar tracking systems are add-ons to solar mounts that are designed to help turn the panels to face directly at the sun throughout the day.

While solar roof panels typically track the sunlight and swivel to keep the panels oriented properly, they could be expensive and difficult to install. In contrast, pole-mounted or ground-mounted units can offer similar benefits at a lower installation price. A ground mount is a durable frame that mounts right to the ground on your property. One well-installed pole is capable of holding a surprisingly large number of solar panels—at times, up to as many as sixteen. In other words, your roof is not your only option.

The best way to determine which of the mounts you want for your property, and which are best poised to increase its value, you should consult a trustworthy contractor. Be sure to get an in-person assessment from your contractor, allowing the installer to suggest options and explain potential benefits and, sometimes, challenges. Either way, a local expert will help you get the most of your home improvement project, no matter the season.

If you’re looking for some guidance, we can help.