What is Google Project Sunroof and Is It Accurate? (2024 Guide)

How Does Google Project Sunroof Work?

Project Sunroof is a smart tool using satellite imagery, 3D modeling and shade calculations from a combination of Google Maps, Google Earth and machine learning technology. However, Google doesn’t work alone in this.

According to its website, Project Sunroof also uses weather and solar savings data from the National Renewable Energy Laboratory (NREL), as well as utility electricity rates, solar costs and tax credit data from other third-party sources.¹

Additionally, a machine learning algorithm is trained to recognize solar panels from satellite images and obtain information about which buildings are already using solar panels.

How to Use Google Project Sunroof For Your Home

Google Project Sunroof is pretty user-friendly. You can get a quick, personalized solar analysis for your home with just three simple steps:

1. Search for your home
2. Add your electric bill information to get a more accurate solar savings estimate
3. Compare solar financing options

How to Use Google Project Sunroof For Your City

Another function Google’s Project Sunroof offers is the ability to see solar data for an entire city. For example, in Fresno, California, 96% of rooftops are viable for solar. If all were to reach solar capacity, the carbon offset would be equivalent to taking 278,000 cars off the road each year or planting 21.3 million trees.

How Accurate is Google Project Sunroof?

When it comes to solar potential analysis, Project Sunroof is a helpful tool. However, we’re a little wary about its accuracy when it comes to solar costs and incentives. We say that because — as noted in this screenshot and confirmed by its changelog — a lot of Project Sunroof data hasn’t been updated since 2018.² Solar prices and incentives vary a lot over the course of a year — never mind four years.

Just in the past year alone, California rolled out net metering 3.0, which had an enormous impact on how viable solar is in the area, and it likely cut potential savings by between 25% and 50% for many customers.

For example, Google estimates that a solar system in Houston, Texas, would be about $26,000 after applying the federal solar tax credit.³ Using internal solar data from 2024, EcoWatch found the average cost of a solar system in Houston to be about $36,570. As you can see, the figure from Project Sunroof is more than $10,000—almost 50%—off, based on our data.

It also overestimates the solar panel payback period, in our opinion. For that same Houston property, it estimates 16 years, while our internal data suggests it would only take 12 years. However, the long-term benefits do seem to be accurate in this case—$30,000 in net savings as opposed to our internal data, which suggest $32,651.

While solar calculators like this are helpful, the only way to get an accurate solar estimate for your home is to get a quote from a certified solar provider.

Do We Recommend Using Google Project Sunroof?

Here’s the thing: Google Project Sunroof is a great tool, but if you’re looking to install rooftop solar panels, we recommend using other resources along with Project Sunroof.

It can provide some general feedback on whether or not your home is a decent fit for solar, but for specific cost and savings information, you really need more than Project Sunroof alone.

What We Like About Google Project Sunroof

Google Project Sunroof provides helpful information to prospective homeowners about solar potential and the feasibility of adding a solar system. Project Sunroof is a completely free resource, and Google claims it doesn’t make any money off of the tool, which means its sole purpose is to accelerate the growth of solar power to help mitigate carbon emissions. That’s something we can get behind.

Just to give an example of the impact this tool has had, one of the largest rooftop solar installations in Houston was prompted by Project Sunroof naming Houston the “most promising city in the U.S. for solar potential.”⁴ This, undoubtedly, has helped Texas reach the number two spot in the country for solar installations, according to the Solar Energy Industries Association (SEIA).

What We Don’t Like About Google Project Sunroof

While Google Project Sunroof has great intentions and features, it’s not without its flaws. For one, Project Sunroof is also only helpful for those looking for rooftop solar panels and doesn’t provide any data for ground-mounted solar systems.

In our opinion, the biggest flaw of Project Sunroof is that a lot of its information can be outdated in some areas. As we mentioned earlier, much of the app has not been updated since 2018, but solar energy has become more accessible and affordable since then, and incentives change all the time that affect the viability and affordability of solar. As such, Google’s quotes can sometimes be higher than that of a solar installation company near you, and they can also go the other way and be much lower than reality.

Lastly, Google Project Sunroof cannot connect you to a local solar provider. If you’re interested in getting a free quote for your home solar project, click below.

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The cost information presented in this article is derived from a comprehensive analysis, incorporating data from multiple industry sources. The average cost per watt per state was calculated based on figures from Consumer Affairs, Energy Sage, and Berkeley Lab’s Electricity Markets & Policy Department. Additionally, monthly energy consumption and the average monthly cost of electricity were sourced from the U.S. Energy Information Administration, ensuring a well-rounded and accurate representation of the information presented.