Is My House Good for Solar?
Having a wide open roof, or a perfectly south-facing house, isn’t always enough to make your property a good solar prospect.
Is my house good for solar? Wondering if your roof makes the grade? Which direction your roof should face? If solar panels can be installed on a flat roof? What about a metal roof? And does roof pitch matter for solar?
Have a look at our short video, Good Roof Bad Roof. It’s a fun, five-minute game that shows you how to evaluate your property’s solar potential and address the question ‘Is my house good for solar’. Enjoy!
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Transcript: Good Roof for Solar or Bad Roof
Welcome to Good Roof Bad Roof. I’m Mark Durrenberger, the President, and Founder of New England Clean Energy solar installation company. So people ask me all the time “Can solar panels be installed on my roof?” Figuring out if your roof is good for solar isn’t hard but there are a bunch of things to consider. Let me show you what they are and to make this fun I’ve created a game called Good Roof Bad Roof. Sorry, there are no cash prizes in this game, knowledge is your prize.
We’re going to look at aerial images of eight roofs. By the end of our game, you should be able to look at your own home on google maps and figure out if you have a good roof for solar.
Let’s look at our first roof. Is this a good roof for solar or a bad one? If you guessed good you’re right. This roof, which belongs to Sue in our marketing department, is an excellent roof for solar. Its azimuth is facing almost due south and in the northern hemisphere south-facing roofs get the most sun. Also, this roof has plenty of space for solar panels and no shade. It has two skylights but no major obstructions to cast shade on the panels.
Okay, what about this one? Good roof or bad roof? This roof, which belongs to Elizabeth from our sales department, is a good roof even though it faces southwest, not South. It still works. As solar panels become more efficient, roof direction matters less. You still can’t put solar on a north-facing roof and expect your system to pay for itself anytime soon, but a roof facing east, south or west works in many cases.
Next up… Good roof or bad roof. Sadly, for Kim in our marketing department, this is not a good roof. There’s just too much shade on it. Even looking at this wintertime image you can see there are still too many tall evergreens around it. Plus the space is broken up by multiple roofs making it hard to find a big enough area for a solar system.
Most people underestimate the amount of shade cast on the roof by nearby trees. It doesn’t get better in the winter, just because some trees may have fewer leaves on them. When the sun is lower in the sky, the trees’ shadows are actually longer and reach further. For solar to be economical, you need at least six hours of good sun per day, so the shade issue is an important one.
This roof shows how tricky it can be to recognize shade. The aerial view makes it look pretty good — southeast facing and enough open space to make up for all the shade of the southern section. When you look at the street view, you realize the trees ringing the house are all huge pines that will cast serious shade most of the day. The hill behind the house makes this even worse by making some trees higher and their shadow longer. If you’re considering taking down trees for solar but wonder about the environmental trade-off, have a look at my tree math blog article.
Let’s get back to our game. Next up is Roy’s house. Roy was one of our first employees. This roof is a bad one for solar panel installation. Getting trickier, aren’t they? This hip roof has a lot of south facing space but the chimney and hot water panels to the east eat up valuable real estate, and a huge red maple tree shades the rest of the roof. But the story has a happy ending. We installed a ground-mounted solar energy system instead. By the way, vent pipes are another obstruction that get in the way of solar, but we move those for you.
This is my favorite roof to look at. Why? Because it’s mine. Do I have a good roof for solar or a bad one? This is a good roof for solar. You may have guessed bad because of the shape of my roof. Although hip roofs like mine generally have less space to work with than a traditional gable roof, they can work for solar. My larger southwest facing roof had too many obstructions but the southeast facing roof fit enough panels to take a chunk out of my electric bill. And I have triplets, so my electric bill needed some help.
What do you think of this roof — good or bad for solar? This roof is bad. The roof is too old, see the crumbling shingles? But after the owner replaced the roof and removed a few trees and the chimney, it became a great roof for solar. If your roof doesn’t have 10 good years left in it or shingles are cracked or in bad shape, replace your roof before installing solar.
Isn’t this fun? We’re almost done. What about this roof, which is made of metal, not asphalt shingles, like most New England roofs? If you guessed good, you’re right. Standing seam metal roofs are great for solar. Corrugated metal, too, Our installers love working on them. Rubber roofs also work. Cedar shingles and slate tiles usually cannot support a solar energy system.
We’re going to end with a doozy. Is this a good solar roof or a bad one? If you said good, you’re smarter than I am. It took me awhile to figure out how to make solar work on this house. Many installers probably wouldn’t have even bothered. The multiple roofs with different azimuths and pitches plus the vent pipe and chimney made this a tough roof to work with. But the customer named Jim insisted we find a way. It was after we saw his determination that we decided to hire him as our CEO.
That’s it for Good Roof Bad Roof. If you want more on what makes a good solar roof, check out my “Is my roof good for solar” blog post. Thanks for playing and thanks for thinking solar.
This video addresses the answer to the question Is my house good for solar.