A Solar Checklist of Sorts
When you put solar panels on your home, you are installing an appliance that will yield benefits for decades. To maximize those benefits, it is important to analyze the installation site to make sure it is optimally suited for solar production. Many newer homes are, though factors like shading, roof geometry, roof material, structural integrity, and homeowners associations can create obstacles. Some of these obstacles may only slightly limit the available solar resource that the home receives, while others may increase installation costs or make solar entirely unfeasible.
When our System Designer comes to your home to perform a survey, they are analyzing all of these factors, but you can get a headstart yourself with the guide outlined here. In this article, we’ll go over the most important home characteristics that help or hinder your solar prospects.
Since we’re generating electricity from sunlight that falls on your roof, it’s probably obvious that we want to minimize the degree to which obstacles like trees and other buildings come between the sun and your shingles. Some shading in the early morning or the evening--when the sun’s intensity is the lowest--may not have a significant impact. Additionally, because we in the northern hemisphere are visited by a southern sun, any object to the north of your home is not typically a problem. However, trees or buildings to the southeast, south, and southwest can eat into the valuable daylight hours between mid morning and late afternoon.
Minimal shade during that time window may decrease your home’s solar potential only slightly. More extensive shading may reduce your solar resource enough that it significantly impacts the return on investment of the entire system. Determining where you fall on this spectrum can be difficult, but we’re here to help! When you schedule a site survey with us, we will evaluate your roof from aerial imagery. If it looks like your roof has potential, we will come out to take more detailed measurements as part of a site survey using a specialized tool called a Suneye.
Roof Aspect and Orientation
When you determine how much sunlight falls on your roof generally, the next step is to evaluate whether you have enough space for a solar system on a section (or sections) of your roof facing in the direction of the sun. As mentioned above, the sun travels from roughly east to roughly west in an arc through the southern sky. Therefore, most roof surfaces with an east, south, or west aspect have significant solar resource.
Residential solar systems range in size from fewer than six panels to more than forty, with the average system being around twenty. When we size your system, we are balancing a number of factors, including your electrical consumption habits, your budget, and your personal goals for the project. However, available roof space can be a big limiting factor. Residential solar panels are roughly 40” x 66”, and you may be able to get a sense for how many will fit on your roof through estimating your available roof space from the ground or from aerial imagery online. However, please do not climb on your roof to collect measurements--leave that to our trained and skilled System Designers!
After we determine the available space, we look at your roofing material. While attachments exist that allow solar panels to be added to virtually any roof type, some materials are considerably easier to install on than others. Standard composite shingle, standing seam metal, corrugated metal, and Thermoplastic Polyolefin (TPO) roofs--for example--can all be attached to easily and inexpensively. Tile and cedar shake can be somewhat more difficult to install on, and metal shingle roofs can be prohibitively expensive.
For many roof materials, the age of your roof is a key consideration. When your roof reaches the end of its lifecycle and is ready to be replaced, your solar system must be removed and later reinstalled. While this is a service that Sunlight Solar provides, we recommend that you avoid having to bear the cost of an uninstallation and reinstallation during the standard lifetime of your solar system.
Though the first solar systems that were produced in the 1970s are still functioning, the standard lifetime for solar is typically said to be roughly 30 years. Because most metal roofs last considerably longer than that, the age of a metal roof is not typically a concern. However, composite shingle and cedar shake don’t last as long as metal, and for those materials it is best to install solar in the first 5-10 years of the roof’s life. If you’re not sure how old your roof is, our System Designers will perform an inspection during your site survey.
Beyond the external characteristics of your roof, its structural characteristics may also affect your ability to go solar. We’re not so much concerned here with whether your home can support the weight of solar panels--they are actually quite light. Instead, we need to make sure that your home will gracefully withstand the moderate upward force created by the panels interacting with the wind.
Homes typically either have rafters or pre-engineered trusses, though many structural designs exist. A home with pre-engineered trusses is more than strong enough to bear a solar installation, though many homes with rafters will also pass muster. Roofs with rafters that span a very wide distance, or alternative roof designs, may need to be analyzed by a qualified engineer before a local jurisdiction will issue a permit for solar installation. In the worst case, roofs may require reinforcement before solar is added. Sunlight Solar provides engineering and reinforcement services, ensuring that all aspects of the project managed effectively and are subject to rigorous quality standards.
You may have the sunniest and most structurally sound roof in your neighborhood, but if your neighborhood’s utility doesn’t offer a net metering program you will not be able to maximize the return on your solar investment. Net metering is a process that allows you to offset your consumption (the electricity that you draw from the grid) by your production (the electricity that you produce with your solar system). Call or visit your utility’s website for information about their net metering offerings. For more information about how net metering works, see our Solar Learning Center article dedicated to this topic.
In addition to having access to net metering, the utility company may determine whether you are eligible for local incentives or grants. Many utilities offer grants for the installation of solar on businesses or rural properties, and third parties may offer incentives to the customers of specific utility companies. For more information about the incentives available in your area, please see our residential solar page.
HOA and Historical District
Beyond any physical characteristic of your home or electrical service, homeowners associations (HOAs) and historical districts are the final common obstacle that can affect your ability to install solar. Some HOAs permit solar, especially in places like Oregon, where they are legally obligated to do so. However, more restrictive HOAs and historical districts may not permit solar at all. If you live in an area with an HOA or historical district, you can often learn about its solar policy by calling or visiting its website.