Learn about the effects of extreme weather on commercial solar panels

November 7, 2017

Learn about SunPower’s solar carports



Listen and learn about the effects of extreme weather on commercial solar panels

If you’re an organization located in an area of the U.S. where Mother Nature can dish out some extreme weather conditions, listen up. Are solar panels and wind a problem? What about solar panels and snow? And solar panels and hail HAVE to be a concern, right? 

This podcast explains the effects of weather on solar panels and can help you determine if you should even consider a commercial solar installation. (Spoiler alert: You should.) In this episode of the SunPower Business Broadcast, host Jeff Allen asks solar expert Zach Campeau, “Do solar panels work during extreme weather?” Hear Zach’s answers—and be sure not to miss his story about fist-sized hail.  


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Jeff Allen:  Hello, everyone. Welcome back to the SunPower Business Broadcast. I’m Jeff Allen. When we think of solar power, solar energy, we often think of – and this makes sense, right? – the sun shining and warmth and blue skies and just the perfect weather conditions. This is for all of the obvious good reasons. As many of our listeners are very much aware, there are plenty of areas in the United States and all around the world, for that matter, where Mother Nature and all the weather that she brings forth – rain, snow, wind, other types of extreme conditions including hail, extreme heat, for that matter – how do those extreme types of conditions affect the operation of solar panels? Does that have any kind of negative effects on the power that they are supposed to generate for us?

Well, we’re going to find out because, once again today, we’re joined by Mr. Zach Campeau. Zach is an incredibly knowledgeable veteran of the solar industry. You might remember, he’s been a previous guest on our program before. Today, he’s going to talk to us a little bit about how commercial solar systems handle extreme weather conditions. Zach, it’s been some time. It’s good to talk with you again. Thanks for making some time in your day to chat with us.

Zach Campeau:  It’s great to be back. Thank you, Jeff.

Jeff Allen:  We appreciate it and we’ve been looking forward to this discussion. We’ve just kind of talked a little bit about this ideal mindset we have of ideal weather conditions to help us generate power through those solar panels, through the solar installation we recently had installed, or that we’ve seen installed. You could talk about residential or commercial, really.

Today, thinking in terms of commercial solar installations, we often don’t think of the cooler months of the year – the cooler seasons. It might include late fall all throughout the wintertime or early spring – November through March, let’s say. Does it make any sense for companies located in colder climates where the sun doesn’t always shine 365 days a year to consider solar power?

Zach Campeau:  Yes, absolutely. Albeit counterintuitive, these sites actually are very promising for solar. Just as a couple of anecdotal examples – Germany, which is famously not sunny, famously has one of the largest installed capacities of solar in the world. A couple of years ago, I think over 50 or 60% of the energy from the grid came from solar energy. It certainly works in higher latitudes. Within the US – New York, New Jersey, and Massachusetts are among the top ten states with the most solar capacity installed. Again, we don’t exactly think of those as having weather like Hawaii or Phoenix or Florida certainly. Why could this be?

Well, it’s because the cold weather doesn’t have a huge effect on your production. There’s no real liability issue from the temperatures that we’re talking about here. Temperatures are tested from -40s Fahrenheit all the way up to 185 Fahrenheit. They’re certified to operate within that range. We’re certainly not exceeding that range even with some of the worst weather that’s out there.

However, of course, with the winter, we think of cloudier days. The sun is lower so there are fewer hours of daylight and this certainly has an effect on production. On the other side, these electrical systems actually perform better as they get colder. We could go into some devices. It might get a little too much for this particular meeting but suffice it to say that certain electrical characteristics, as temperature goes down, become more favorable to the production of energy.

On top of all of this, of course, is the specifics of that site. What are the electricity rates like? What is the type of mounting that we have? It should be considered as a whole. Any competent solar company should be able to put together an expected energy for your site. From that, you could start working towards a financial format to figure out how solar will benefit you.

Jeff Allen:  I think you kind of helped to debunk some of the myths there. In fact, in the wintertime, we know that there are some portions of the country that experience quite a significant amount of snowfall. You’re talking about snowfall that can take and bury these solar panels under a certain degree of snow, perhaps, as much as several feet, in certain cases. Talk to us about the effects that snowfall could have on these solar panels and their ability to generate the power that we need for our businesses.

Zach Campeau:  Absolutely. Any product is going to be designed to be used in as many places as possible. It wouldn’t make a lot of sense for people to design a solar panel that only works below, say, the latitude of Los Angeles. It would be limiting the market a lot; especially when we know that solar panels work fine in cold weather. So what about snow and how do we check it? There’s actually industry standard certifications that are used where they take a panel, mount it, and then start loading sandbags on it. There’s different levels of the certification. A pretty typical one is 5400 Pascals, which is the unit of pressure. To put that in context, 5400 Pascals is about equivalent to one ton of weight on the front of the panel, which is a pretty significant amount of snow.

Jeff Allen:  So we’re talking about a significant amount of pressure then, Zach. If I’m looking at them as just kind of a guy with average knowledge of how solar power works, and I see a bunch of snow piled on top of those solar arrays and I just had these panels installed and they’re buried two or three feet deep in snow or whatever the case might be, are those solar panels still going to be effective in being able to generate the power to bring that sunlight in through?

Zach Campeau:  Certainly the production will go down because the panels are covered with snow but unfortunately, snow happens in the time of the year that there’s not a lot of sunlight. When you look at the financials for sites towards the North, most of the energy that pays for the system in the first few years is occurring during the summer when the snow isn’t there and that’s where the sun is in the sky for hours and hours a day and there’s lower probability of having cloudy weather. Interestingly, the snow happens at the best point in the year because the sun is the lowest and the weather is the worst. But it’s also important to know, just letting it melt with the rest of the snow on the roof is completely fine. Even if there’s a bunch of snow piled up there, the building owners don’t have to spend additional resources going to clean that snow off.

Jeff Allen:  In other words, Zach, just to kind of give us some clarity on this, we shouldn’t have to worry so much about that snow because our solar panels have been generating enough power that we will have enough in excess or in storage or in reserve, I guess you might say, that would allow us to continue to operate even if those solar panels are buried knee deep in snow.

Zach Campeau:  Right. I think reserve is the key term there. While onsite physical storage – what we think of as batteries and things like that – those are just starting to roll out to the market. What’s much more typical, and has been for years, is something called net metering, where it’s almost like, picture a ledger that you and your utility keep. Each time you make a kilowatt that you’re not using instantly on your site, you’re selling it to the grid. Then at night or during the winter, you’re buying back electricity generally at a lower rate, especially at night, than you were paid when you produced it. That’s kind of the fundamental economic model for many, many commercial solar systems.

Jeff Allen:  Wind is a real big deal for many of us. I know so many of us who have these shake roofs or tile roofs and we’ve seen these things blow off in the wind. Is that ever something that we need to be concerned about when it comes to our solar panels as well as damage from wind and wind gust?

Zach Campeau:  If you think about what the wind is actually doing to the panel, you’ve got a large aluminum frame and a piece of glass so it’s kind of pushing a force on it similar to how you would imagine that snow load being applied. However, with wind, it can be applied on the front or the back, so the certification testing that they do for wind is actually very similar to snow. They load the front; they load the back; and they cycle it a few times to simulate that.

What some kind of best-in-class companies will do is, they’ll do additional qualification tests where they’ll do thousands of cycles back and forth using really kind of comical-looking machines like two giant pillows that are pushing back and forth or vacuum pumps and things like that. That ensures that the products will last not just three or four very severe cycles, but thousands and thousands of intermittent cycles that we expect on a typical roof.

On top of that, some companies will go out and actually achieve additional certifications so that these types of tests can be conveyed to the customer. Examples of that are things like cyclonic load testing. For instance, that’s one that they use in Australia to make sure panels will stay adhered to the surface even through a category 5 cyclone.

Jeff Allen:  Wow. At least efforts are made in order to try to duplicate the kinds of pressures that they would actually realize out there in the real world. Now, I thought of a weather situation here, Zach. This would have to have some kind of damaging impact on the solar panels or on my installation as a whole – that would be hail. I would imagine that there has to be some kind of concern that you or other people in the solar industry might have about installations being able to withstand the damaging impacts of hailstones.

Zach Campeau:  Well, you probably wouldn’t believe me. I sound like a broken record at this point but we do actually have a certification for that as well. What they do is, they take ice balls that are an inch, an inch-and-a-quarter in diameter and they stuck them in an air gun, almost like a potato cannon, and they start firing them at the solar panel, at different parts of the panel as well, and then we measure the power. The official certification level is about 5% power loss after all those hits. If we think about it, 5% power loss is actually a lot of power loss. That’s one hailstorm. Imagine you have one of these hailstorms, I don’t know, every five years – a very severe hailstorm. You can actually start having significant power loss.

It’s very important to understand how the particular solar technology you’re looking at handles these types of impacts and the cracking in the solar cells that can happen from them because the same sort of impact stresses that you have from hail, you can have from shipping; from installation; from maintenance. It’s important for consumers to be aware of how the product or the technology that they’re looking at deals with these types of stresses. Even if a solar cell within the panel does get cracked, what happens? Understand how that could affect their investment.

Jeff Allen:  It would be something to actually see kind of those tests and to see the kind of types of damage that the cells themselves can withstand. When I think about it, 5% power loss – while you say it’s actually pretty large – I think about it in terms of the 95% of the power that wasn’t lost. Really when you think about it, the amount of loss is probably a little smaller than I think most people would consider at first blush.

Zach Campeau:  Fair point because, coming from reliability, it’s my job to obsess about the tenths of percents.

Jeff Allen:  Yes, right.

Zach Campeau:  So thank you for a little perspective there. As an anecdotal story, we had a site in Phoenix that had several thousand panels. It was a typical commercial roof with that white TPO membrane plastic that covered most of it. They had fist-sized hail and they had to file an insurance claim to repair the numerous gouges in the roof. The part that was covered with solar panels was completely fine. Actually, it almost served as armor for the roof, more than anything else.

Jeff Allen:  Oh my goodness. You could probably say that – well, that is not necessarily a typical scenario but it just goes to show how durable the materials are in the solar cells that are being able to withstand the kinds of damages that only Mother Nature could dish out.

Zach Campeau:  Exactly.

Jeff Allen:  Zach, as we kind of wrap up our conversation here today, I was wondering if you had any thoughts about maybe some other questions that are weather-related about solar energy, about the power that these installations can in fact continue to generate even during the worst of the worst case scenarios.

Zach Campeau:  Two stresses come up a lot, which we haven’t covered. One is, extreme heat, which is very similar to extreme cold. It’s rare, or nearly impossible, that the actual weather would get above the operating range of a panel, which is 185 degrees Fahrenheit. The heat question comes up but it’s straightforward.

Something that we also get a lot of questions about is salt exposure because people want to put solar panels on their beach house or maybe they’re just near the coast. In those cases, it’s important to understand if there are any limitations or clauses within the warranty that would exclude that sort of an installation. By and large, solar panels can be designed to survive in that environment but you need to make sure that the products you’re looking at are appropriate for it because of course it all comes down to the design and the material choices.

Jeff Allen:  Zach, thank you so much for spending some time chatting with us today and kind of setting the record straight. Hopefully, this information will help our listeners understand that even if their businesses are located someplace where it’s not an average of 72 degrees and sunny most of the time, that solar power can still be a very viable option for them. Again, I want to thank you so much for your time today.

Zach Campeau:  It’s my pleasure. Thank you, Jeff.

Jeff Allen:  That’s Zach Campeau. I hope that you enjoyed this visit with Zach. This is the second time we’ve had a chance to chat with him. We appreciate his being able to once again come by and share his information and expertise with us.

That wraps up another interesting episode of the SunPower Business Broadcast. Keep in mind that all of our podcasts along with a whole lot of other information available on sustainability, renewable energy, as well as the solar industry in general is all available on the business feed at BusinessFeed.SunPower.com. Until next time, we invite you to join us in helping to change the way our world is powered. My name is Jeff Allen. So long for now.

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