DIY Site Survey: How to Assess Your Home’s Solar Potential in 3 Steps

Before you can lower your carbon footprint through solar power, before the panels go on your roof, even before the system is designed, the site for the potential solar project needs to be properly surveyed. 

So what is a site survey? 

A solar site survey is a comprehensive evaluation of a home’s potential to produce solar energy and one of the primary services a solar company provides in its initial consultation.

Although solar site surveys are generally conducted by solar professionals, homeowners can partially assess the home themselves. If you’re considering solar panels for your home, and would like to educate yourself on your home’s capacity for solar energy, read through our site survey checklist below:

1. Inspect Your Roof

Unless you are or know a professional roofer, we don’t recommend anyone climbing up on their roof to perform a physical inspection. That said, the roof inspection is the first and most important step in any solar site survey. 

Even without physically getting on your roof, answering a few questions can help you quickly determine if solar is right for you:

What is the condition of your roof?

Because the solar installation team will be affixing the mounting equipment that supports the solar panels directly onto the roof — literally drilling into it — it’s important that your roof be in good condition. Per Citadel Roofing & Solar, a roof’s “age” has more to do with the weather it’s sustained than the number of years, i.e., severe wind, rain, and snow can age a roof faster than time sometimes can.

Even so, a roof that is several decades old may not reveal any structural instabilities until after someone starts drilling into it.

Not sure how old your roof is? Janney Roofing identified a few strategies to help you determine the age of your roof. If you’re unable to ask the previous owner (you can also have your buyer’s agent contact their seller’s agent), you can contact your local county permitting office. Several US counties require a permit to replace the roof. 

How big is your roof?

In solar, bigger is not always better, but size does matter. Your roof’s surface area, pitch, and slope direction all affect its potential solar output. 

But if you’re thinking that completely covering your roof with solar panels will negate any size issues, you might remember another trite phrase: sometimes, less is more. More solar panels doesn’t guarantee more solar output (we’ll discuss this more in the next section about shade), but it does guarantee more cost.

Measuring your roof properly ahead of time will help you identify the optimal number and placement of solar panels later.

You can get a rough estimate of your roof’s surface area and pitch without ever stepping foot outside:

• Surface area — Google Earth has a handy measurement tool to help you gauge distances and areas. Simply enter your home address into the search bar, then click the ruler icon on the left. You can then outline the perimeter of your roof (note: this is only a two-dimensional rendering and does not account for pitch).
• Pitch — examining pitch is a bit more hands on, but you can follow this useful guide from This Old House. All you need is a level, a tape measure, and a pencil.

What about shade?

Not surprisingly, solar panels work the best when they’re exposed to lots of sunlight and are less effective in the shade. If trees, buildings, or other outdoor structures are casting a consistent shadow over significant portions of your rooftop, solar panels may not be a viable option for you.

One way to quickly assess the hours of usable sunlight available to your roof is through Google’s Project Sunroof app. Project Sunroof is a free tool that uses satellite imagery and 3D modeling to determine factors like available sunlight, roof size, and potential solar savings through various financing options like direct purchase, solar loans, solar leases, and power purchase agreements (PPA).

Note: Project Sunroof is not available for all US addresses. If this is the case for you, you can conduct a simple eyeball test and answer the following questions:

• What potential obstacles around your home could interfere with the sunlight? Can any of them (like tree branches) be reasonably and safely removed?
• How much of your roof is south facing? In the Northern Hemisphere, the sun resides in the southern part of the sky, meaning south-facing roofs tend to receive the most direct sunlight during the day and experience less shade.

2. Review Your Utility Bills

Every Energy Consultant in the industry will mention the importance of reviewing your home’s historic energy usage, with 12 months representing the average sample size. 

Simply put, you won’t know how much solar energy your home needs if you don’t first know how much energy your home is consuming.

Even if your energy consumption has not significantly changed in the last 12 months, chances are you’re paying more for electricity now than you were a year ago. Most utility companies will raise their rates anywhere between 1 and 3 percent each year partly to keep up with inflation, partly to keep up with demand. You can find the retail rate of electricity (expressed in dollars per kilowatt-hour, or $/kWh) directly on your power bill and see how that rate has fluctuated over the last year.

Coupled with the steadily rising cost of electricity is the steadily decreasing price of residential solar. A previous piece discussing the various types of solar companies available to homeowners identified the time we’re living in as the “golden age of solar.” 

The bottom line? Offsetting your energy usage with a solar energy system has never made more financial sense than it does now.

Calculating your solar offset and savings

You don’t need to be a mathematician to calculate your solar offset, but you will need to do some important preliminary research if you want to do it right. To determine how much solar power can reduce your power bill, you’ll need the following inputs:

1. The desired capacity of the solar panel system, expressed in kilowatts (kW)
2. Average daily sunlight, expressed in hours (consult the heat map from Unbound Solar below)
3. Your average daily energy usage, expressed in kilowatt-hours (kWh)
4. The retail rate of electricity found on your utility bill, also expressed in kWh

Then, enter those values into the calculator below:

Establishing goals

Projecting your total solar savings each year raises some important questions: 

1. What goals do you want to achieve by making the switch to solar?
2. How much money do you want to save each month?
3. By what amount do you want to reduce your home’s carbon footprint?
4. How important is energy independence to you?

The answers to these questions will greatly inform not only your decision to go solar, but also to consider possible system upgrades that could increase your solar energy system’s efficiency:

• Solar batteries — solar energy storage solutions are becoming less expensive and more available by the year. According to a report by Wood Mackenzie Power & Renewables, the solar battery market is expected to reach nearly 7.5 GW of installed capacity by 2025, and over 19 GW by 2030. They provide backup power during times of high demand, grid outages, or peak evening hours.
• EV integrations — another way to maximize savings and reduce your overall carbon emissions is by integrating an electric vehicle charging station with your solar power system. The National Renewable Energy Laboratory (NREL) estimates that the number of residential solar and EV charging systems in the US could reach 40 million by 2030, representing a 1,700 percent increase from 2020 levels.

The availability and cost of the above mentioned system upgrades depends on where you live and what solar company you choose to work with.

3. Research Incentives

Depending on where you live, solar users have several federal, state, and local incentives available to them to help ease the large upfront investment a solar panel system requires. Thanks to the Inflation Reduction Act, many of the incentives that were set to expire have been extended and fortified, making solar power all the more viable and affordable for Americans. 

Below are some of the main solar incentives and tax credits worth researching as you make your solar plan:

1. Federal Investment Tax Credit (ITC) — this tax credit is worth 30 percent of the installed system costs through 2032, 26 percent  in 2033, 22 percent in 2034, and expires after that.
2. State and local incentives — many states and local governments offer additional incentives for installing solar panels, such as rebates, grants, or property tax exemptions.
3. Net energy metering (NEM) — this program allows homeowners with solar panels to receive credits on their utility bills for excess electricity generated by their solar panel system and sent back to the grid. Read our piece on net metering in the United States for more information. 
4. Solar Renewable Energy Credits (SRECs) — some states have programs that allow homeowners to earn credits for the solar energy generated by their system. These credits can be sold to utilities to help them meet their renewable energy requirements.
5. Utility rebates — some utilities offer rebates or other incentives for customers who install solar panel systems.
6. Sales tax exemptions — in some states, solar panel systems are exempt from sales tax.

As alluded to before, when it comes to solar energy, not all states are created equal. To view the incentives and tax credits available in your state, visit our solar states page for a full breakdown.