Does My Solar Roof Have to Face South?

Understanding Solar Roof and Solar Panel Orientation

You don’t need optimal conditions for your solar power system to be a great investment. One of the biggest myths about the financial viability of solar is that it requires a really sunny location and a south facing roof. While these may be ideal conditions, folks outside of Southern California with roofs that face other points on the compass, such as east to west-facing roofs, can still satisfy most of their electricity needs and reap significant financial returns when they adopt solar power systems.


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South Facing Roof Not Required For Solar Homes

solar roof with panels facing south energysage

This beautiful solar roof is facing south into the sunlight but could be equally as efficient with a different roof orientation.

We looked at differences in solar panel production and savings in different areas of the country in our post Top 10 Cities for Solar (Hint:  They Aren’t the Sunniest). But what happens to these numbers when the roof in question doesn’t face south?  We took a closer look at six cities– Boston, Los Angeles, New York, Chicago, Philadelphia, and Washington, D.C.—to see what happens with their solar roofs. Here’s what we found:

Even when solar panels aren’t facing directly south, they can still produce large amounts of electricity, even if you live somewhere that doesn’t receive much sun. In general, regardless of where you live, if your solar roof is oriented directly east or directly west instead of the optimal south-facing, you will only see a 20% decrease in the amount of electricity you produce. Even with this decrease in performance, your solar panels would still produce enough electricity to save you hundreds of dollars a year.




south facing solar roof graphic




Solar Panel Orientation in Cloudy Cities

Additionally, lowering the tilt angle of the panels on your solar roof can also contribute to the total economic benefits east and west-facing solar power systems provide. Panels facing directly east or directly west with a 30° tilt, produce about 20% below peak performance levels. If the tilt is dropped to 15°, production levels at the east and west extremes only decrease by about 15%. While this 5% gain may not seem like a significant difference, this slight change in panel orientation can be enough to save an additional $50-$75 per year even in cloudy cities.

Let’s look at Boston to see how the numbers work.  Boston, unlike somewhere like San Diego, is not known for its abundant sunshine, but an average-sized, east-facing solar system in Boston is still capable of producing more than 4600 kWh of usable electricity per year. That’s enough to save more than $650 each year on electricity bills. If you adjust the tilt angle of those panels to 15°, the savings will be between $700 and $725 per year. Those savings in and of themselves are significant, but when you consider that Massachusetts residents qualify for local, state and federal incentives such as tax breaks and solar renewable energy credits (SRECs), the financial returns of adopting solar power, despite the “sub-optimal” conditions become even greater. The point is, you don’t have to have the perfect climate and the perfect south facing solar roof to reap the tremendous financial benefits that solar power can deliver. When it comes to solar, good enough is almost always more than enough.

Assessing how the different performance variables, such as solar panel orientation, will affect your financial outcome can get complicated, but the EnergySage Solar Marketplace will help you to get multiple quotes from qualified installers and then automatically calculate the financial benefits each option provides, making it a lot easier to maximize the returns on your investment.

4 thoughts on “Does My Solar Roof Have to Face South?

  1. Ollie

    Interesting study, although southern facing solar panels obviously still make the most sense if they’re an option. I’d also like to mention that specialized mounting solutions have gotten a lot more affordable and effective over the years. Systems like the one recently developed by TRA Snow and Sun (see here for more info: http://trasnowandsun.com/tra-snow-and-sun-develops-new-solar-mounting-design-for-east-west-facing-solar-mounting-project-in-las-vegas/) allow homeowners with east west facing roofs to still reap the full benefits of solar energy.

    Reply
    1. CharliChuckec

      All true, but the point is that due to the fact that home builders for decades have ignored the orientation of the buildings, South is not an option for many, and if turning the panels on a mount only gains 15%, it may well not be worth it given the aesthetic and mounting costs. In particular, this means that a passive solar air or water heater mounted on an outside wall is very practical–and heat is far more efficient in using solar than PV. Payback on a passive wall heater is under 24 months in many cases. Such a system in snow country, will work fairly even on the north wall, although the payback period will be longer.

      Reply
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