What's the Best Direction for Solar Panels?
It’s a fact—the orientation of your roof affects how much energy solar panels can potentially produce. Still, it’s not as straightforward as assigning a “one-size fits all” hard and fast rule for solar panel placement. For homes in the northern hemisphere, south-facing solar panels do receive the most direct sunlight throughout the year. However, a south-facing roof is by no means a necessity for a productive and economically viable solar power system.
A rooftop solar power system facing east or west can still generate enough energy to meet your energy demands—particularly if it’s paired with a home battery backup system. Solar panel direction is one of several factors that determine the viability of rooftop solar. Here is a breakdown of the role roof orientation plays in producing clean, renewable energy for your home.
Solar Panel Placement: East-West vs South Solar Panels
In the northern hemisphere, since the sun’s path is always in the southern sky, static, south-facing panels are able to soak up the most sunshine during the year. Panels angled to the southwest or southeast produce around 8% less than their due-south counterparts. If the solar panels face directly east or west, the production is closer to 20% less than directly south-facing panels.
The orientation of your roof does influence solar panel production, but it is not the most significant influence on a solar power system’s cost-effectiveness. The cost of your electricity and the available state and local solar incentives have a bigger impact on solar’s Return on Investment (ROI) than how much power the system is able to produce. This is why less sunny states, like Massachusetts, New York, and New Jersey, still rank in the top ten states for solar capacity. They have expensive electricity and solid solar incentives. Click here to see how your state stacks up in supporting solar.
Your electric utility’s rate structure can also influence the importance of roof orientation. If your utility uses a time-of-use (TOU) pricing structure, then your electricity costs more at the highest usage times (peak demand). These high demand periods are generally in the afternoon and evening, as people return home, turn up the AC, cook dinner, etc.
West-facing solar panels receive the most sun at this time and, therefore, displace more grid energy during these peak demand periods. One study found that west-facing panels generated nearly 50% more than south-facing counterparts during peak demand hours when normalized for a 5.5 kW system. So, although the overall production is less, west-facing panels are producing energy when it matters the most for savings.
One alternative strategy to mitigate peak demand pricing is to install an energy storage system with your solar panels, such as the new Humless home batteries now offered by IPS. With a home solar battery, no matter what direction your solar panels face, so long as they’re able to generate energy, you’re able to store energy for consumption when electricity is most expensive, thereby maximizing your savings.
What if a North-Facing Roof is My Only Option?
Getting meaningful production from solar panels on a north-facing roof requires mounting them in opposition to the roof slant. That results in a more considerable aesthetic impact, and the total production will still be less than with south, east, or west-facing systems. You’ll still see a few of these setups on older systems here in Colorado that have no alternate roof space available, but generally, in these instances, it’s helpful to consider non-roof locations for solar on your property and to utilize solar ground mounts or pole mounts instead of roof mounts.
Generally, the roof is the best opportunity for a large, unshaded space on your property. Still, if you have sufficient yard space, a ground-mounted system can actually be cheaper than a roof-mounted one. Ground-based solar panels also offer easier maintenance access and create shade for landscaping or gardening.
Roof Pitch Also Matters for Solar Panel Orientation
Though less impactful than the roof orientation, the angle of solar panels also affects production. The goal is to maximize sunlight that hits the panels at a perpendicular angle. If the panels are to be mounted flush with the roof, then the steepness, called roof pitch, decides the angle of the solar panels.
The ideal angle for south-facing panels here in the U.S. is between 30 and 40 degrees (unless you’re in Alaska where panels need to be angled much steeper). The system’s latitude will determine what the exact best angle is for solar production. Steeper angles have the added benefit of helping with maintenance, as snow and debris tend to slide right off.
East- and west-facing panels generate more energy when mounted flatter than 30 degrees. For example, east or west-facing solar panels that are at a 15-degree tilt trail the production of south-facing panels by 15% instead of 20% when at a 30-degree tilt.
Sub-optimal roof pitch can be corrected by constructing a mounting system that angles the panels to a preferred tilt, but this typically comes at a premium. Homes with flat roof are often able to utilize ballast-mounted systems, which have the added benefit of not requiring roof penetrations or additional racking.
There is Much More to Solar Than Roof Orientation
South-facing solar panels produce the most energy in the northern hemisphere (if you’re in the southern hemisphere, please reverse everything), so if the opportunity is there, go for it! If a south-facing orientation is not possible, there is no need to give up on your solar goals. Alternative orientations and placements can still offer considerable generation and utility bill savings. Find out what’s possible with a free solar quote for your home!
The best news is that solar power system placement is not a guessing game. Our experts at IPS can generate precise solar quotes using the specifics of your home (or business), including roof orientation, to show how much energy you can expect from your system, year after year.