It’s a beautiful sunny day here in Austin, Texas. There’s not a cloud in the sky, and a cool spring breeze is whistling through the blossoming trees. But as any good Texan knows, the weather can change in a matter of minutes, and it’s best to be prepared for any occasion.
In the same vein, if you’re considering getting solar panels for your home, it’s important to understand how the weather will affect solar panel efficiency. If for instance, your home is located in a region prone to hail and lightning, it may be in your best interest to look at higher quality panels or additional grounding equipment. Similarly, homes in the American Southwest should be mindful of how extreme temperatures could affect the performance of their solar panels.
The good news—and there’s always good news with solar energy—is that photovoltaic (PV) solar panels have evolved to become incredibly durable, even in Earth’s most extreme environments. You’ll find them in Antarctica and Iceland. You’ll find them in the scorching heat of the desert. Once you’re satisfied that they’re a good investment, you may soon find your very own money-saving solar panels on your roof!
Solar Panels and Cloudy Days
There are some pretty standard myths that have unfortunately been attached to any talk of going solar, but the question “Do solar panels work on cloudy days?” is by far the most popular. Before we can understand the effect clouds will have on solar panel efficiency, we first must understand what’s important to the smooth operation of your solar panels—namely sunlight.
In the simplest terms, solar panels need access to the Sun’s energy which makes the 93 million mile journey to Earth in the form of photons. When photons strike a panel, they are converted into direct current (DC) electricity. After being converted to alternating current (AC) electricity via the system’s inverter, you have useable solar energy for your home.
When it comes to weather, you’re generally always going to have significant cloud cover regardless if there’s rain, lightning, hail, or snow. These clouds effectively reduce the amount of sunlight that can reach your solar panels. Depending on how dark and heavy the rain and clouds can be, your solar panels will likely see a sizeable drop in solar panel efficiency. This is also true for fog or mist, but even the foggiest cities in the U.S.—San Francisco comes to mind—receive enough sunlight during the year to power entire homes with solar.
Take, for instance, the example of the blanket and the flashlight. If you’re in a dark room divided by a blanket, and one person shines a flashlight on the blanket, a person on the other side would be able to see the light. Supposing you divide the room with more blankets or a darker, thicker blanket, the person on the other side would see less light. The same principle is true with solar panels. The Sun would be the flashlight, and the solar panels would be the person on the other side of the blankets (clouds).
The reason the “solar panels don’t work on cloudy days” idea is a myth, is because even though you can’t see the Sun, light is still getting through the clouds, even if only a little. Keep in mind we wouldn’t even be able to see anything if light wasn’t getting through!
Luckily solar panels absorb both direct light and diffuse light; that is—light that is not directly shined from the Sun onto the panels. This light is reflected off of clouds, buildings, and other shiny, light-colored surfaces. With any sunlight, your solar panels will produce electricity. Conversely, this is why solar panels do not produce at night time.
Solar Panels and Rain
Where you have rain, you have clouds, and with both comes a decrease in system production as stated above. That being said, rain is surprisingly beneficial to your solar power system as it serves to wash away dirt and debris, essentially giving your panels a good cleaning now and then. Just like cloud cover limits exposure, pollen, bird droppings, and leaves that cover your panels limit the amount of sunlight that’s getting through for conversion. Fortunately, rain serves to wash it all away.
See Also: 5 Tips for Cleaning Your Solar Panels
Frequently we’ll talk to homeowners who are concerned that rain will physically damage their panels, but there is virtually no chance of that happening. After rigorous testing in the laboratory, solar panel manufacturers shield the strings of solar cells that make up the panel in a waterproof encapsulant. This layer is then generally sandwiched between a strong backing sheet, barrier films, and tempered, durable glass to protect against moisture and other weather phenomena. Protective aluminum framing is then force fitted around the layers to ensure the panel’s durability and longevity.
Solar Panels and Hail
If you’ve ever left your car parked in an uncovered area during a hailstorm, you know all too well the kind of icy destruction that can occur suddenly and without warning. Considering your solar panels will be the first point of contact for any incoming hail, it’s important to discuss their vulnerability to impact damage. By extension, let’s throw in the example of the neighbor’s kid hitting a baseball at the panels just for the hail of it. What…too soon for weather puns?
Standards set for by the International Electrotechnical Commission dictate that panels must be able to withstand 1’’ hail traveling at speeds of 50 mph. This is out of concern for the protective solar panel glass shattering and posing a safety issue to the consumer.
This would be the hail equivalent of a ‘light drizzle’ for rain, and hardly poses a threat to panels manufactured by reputable companies nowadays. Panels are engineered to withstand some of the most brutal hail storms, including those with hail traveling at above 260 mph.
So long as you invest in some halfway decent panels, you shouldn’t have a thing to worry about from hail. That being said, it should be noted that Mother Nature can still be quite unforgiving, and your solar panels are not immune to all flying debris.
Solar Panels and Temperature
It seems counter-intuitive to say higher temperatures mean a decrease in solar panel efficiency, right? After all, it’s typically warmer on sunnier days, and you already know that solar panels need sunlight to operate.
As bizarre as it sounds, high temperatures do, in fact, lower the power output of your panels because of what is known as a voltage drop. You see, power is the product of voltage and current (P = V x I), so although higher temperatures increase the current (I in the equation), they decrease the rest state of the electrons within a solar cell.
When sunlight (photons) strike a solar cell, it imparts energy to the cell’s electrons. The potential difference between the rest state and the energized state of the electrons is the voltage (V). If temperature raises the rest state of the electrons, there will be a lower voltage, and, therefore, a lower power output.
This power drop is not generally noticeable unless you live in a region prone to triple-digit temperatures (like Texas), but then again, at the rate climate change is progressing, we may all be living with scorching temperatures soon enough.
Too much physics in this section? Here’s the key takeaway: high temperatures mean less power.
Solar Panels and Lightning
In the highly unlikely event that lightning actually strikes your roof, there is a potentially dangerous voltage transient that can occur though this is easily preventable through the use of a lightning protection system. Such systems are particularly important if you live in the American Southeast, which has the highest rate of lightning strikes in the country.
But even then, you shouldn’t have anything to worry about as any properly installed system is going to be grounded to prevent any electrical surges. If lightning were to strike the panels, the energy would be channeled through the grounding system safely into the earth. If you’re particularly concerned by lightning, there are also several other surge protection devices such as surge arrestors, varistors, and suppressors that prevent dangerously high voltages.
Solar Panels and Wind
When it comes to wind, your concern should be focused on when and where to buy a kite, not on the extremely unlikelihood of wind-related damage to your solar panels. Most panels can withstand winds up to 90 mph (or more), so barring the occasional hurricane, you have virtually nothing to worry about. Just look at this photo from Hurricane Sandy a few years ago. Need I say more? They’re still firmly fixed to the roof!
But in all seriousness, you have little—if anything—to worry about with wind. The only exception would be if your system were improperly mounted on your roof (e.g. the railing system). So long as you go with a reputable solar company, this will never be an issue as there are countless safety requirements to meet final system inspection.
Additionally, wind can actually be a boon to your system’s performance as the cooler air temperature effectively cools the operating temperature of the solar cells. Most rooftop arrays are mounted with several inches of clearance so as to increase air circulation beneath the panels.
Solar Panels and Snow
Although a snow buildup won’t directly damage your panels, it does pose a unique threat to the system as it acts as an increased static structural load. With enough snow, the added weight could potentially cause your roof to collapse, indirectly damaging the panels. If you have that kind of snow accumulation though, electricity generation is likely going to be the least of your problems.
As we mentioned before, a snow-covered panel is not going to generate the same amount of power as one with unimpaired access to the Sun, but that is not to say it won’t produce any electricity at all. If there’s a possibility of snow covering all or part of your panels, it’s important to use microinverters in your system so the snow or debris on one panel will not bring down the efficiency of the entire system.
Read More: What is a Solar Microinverter?
The good news with snow is that—in most cases—even a little bit of sunlight making it to the panels will be enough to warm the panels and melt the snow. Typically solar panels installed at higher latitudes (where snowfall is more common) will also have higher tilt angles so as to maximize the amount of sunlight they receive.
In most cases, heavy snow buildup should simply slide off. If the panels are low enough to the ground, you might also be able to simply brush the snow off with a broom. It is not advisable to be doing this on a snow-covered roof, however.
One additional benefit of snow is that it’s a highly reflective surface that can increase the amount of ambient (reflected) light that reaches a solar panel.
Wondering Whether the Weather Will be an Issue?
Nature can be extremely unpredictable at times, but you should be able to sleep easy knowing that the solar panels you get are capable of withstanding the most brutal conditions. If you were to use the high-quality panels , you’d get some peace of mind knowing they’re backed by a 10-year product warranty and 25-year performance warranty.
But weather should be the least of your concerns when going solar, because regardless of a few cloudy days or the occasional snowstorm, your system is designed to generate clean energy for decades, saving you money that would otherwise be paid to your burdensome utility. All around the world, we’re seeing countries embracing solar energy in spite of frequent, inclement weather. Heck—look at Germany! Until recently they held the distinct honor of having the most solar out of any country, and they practically invented cloudy days!
Again, if you have any additional questions about going solar or potential weather effects, do not hesitate in reaching out to one of our solar specialists. They will be able to give you additional information on local rebates and incentives as well as dispel any other solar myths that you might have heard. Don’t forget to grab your free copy of our Solar Information Packet that answers a variety of other frequently asked questions about going solar. And remember, even on the cloudiest days, the Sun is still shining brightly in the sky!