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Solar Panels and Cloudy Skies

What You Need to Know about How the Weather Affects Solar Power Generation

When most of us think about the best place for solar panel installation, we probably think of some massive solar farms in the deserts of Arizona or Nevada where year-round heat and sunlight are the norm. While those areas might certainly be great options for solar power generation, solar panels have also been installed in places such as Iceland and even Antarctica – regions not generally known for their warm, sunny climate. 

While solar panels, as their name implies, do require sun to produce a sustainable and renewable source of electricity, the efficiency of solar photovoltaic (PV) technology has improved dramatically in recent years to the point that solar panels are perfectly capable of producing large amounts of renewable energy even if your local climate is more akin to Seattle than Sonoma. Below, is a concise introduction to how different types of weather can affect solar panels. 

Solar Power and Cloudy Days

One of the most common questions that people ask when thinking about making the switch to solar power is: “What about all these cloudy days we have?” A common misconception about solar power is that solar panels will not work when it is cloudy. The light from the sun travels 93 million miles before it hits the Earth’s atmosphere. Even on the cloudiest of days, the light from the sun is able to penetrate clouds and illuminate the Earth’s surface. If absolutely no photons from the sun’s rays were penetrating the cloud cover, we simply would not be able to see. 

Furthermore, it is worth noting that solar panel PV technology is able to utilize both direct light and diffuse light for generating electricity. Direct light is the product of the sun’s rays that shine directly on the solar panels, while diffuse light is that which is reflected off of different surfaces such as buildings, windows, bright-colored clouds and other reflective surfaces. Even on thick cloudy or foggy days, solar panels will be able to generate electricity both from direct light from the reflected light in the surroundings. 

In cities such as San Francisco, known for its thick fog that rolls in off the bay, several homes have achieved net zero energy status, meaning they produce all (or even more) of their energy needs through solar power generation. In the characteristically cloudy cities of the Pacific Northwest, such as Seattle, community solar projects have also been put into place to provide a sustainable, renewable energy alternative for people living in the city. When these community solar projects are located within the city limits, they benefit from the large amount of reflected light that bounces off the windows and shiny metal surfaces of inner city buildings. 

Most experts agree that today’s solar panel technology has the ability to produce around 25 percent of their typical output during cloudy days. While that is certainly a reduction in optimal performance, this shows that solar energy production is possible even in areas with large amounts of constant cloud cover. 

blue solar panel with rain droplets

Solar Panels and Rain

When it is raining there is usually a pretty thick layer of cloud cover that will reduce the maximum output of energy from a solar panel system. However, rain also offers numerous benefits that often go unnoticed. Solar panels that are located in sunny locations with limited rain, often see their performance drop due to dust or dirt that accumulate on the surface of the panel. Just as cloud cover reduces energy production, a thick layer of dust will produce a barrier that limits optimum energy generation. 

Thus, placing solar panels in areas where periodic rain showers will give them a free cleaning is usually a good maintenance strategy. Solar panels are surrounded by tempered glass and an aluminum frame, which means the solar cells inside this waterproof encapsulate are 100 percent protected from the rain. Furthermore, solar panels are mounted on an angle to maximize their exposure to the sun, which travels in the southern part of the sky in the Northern Hemisphere, so the rain will also wash away leaves, bird droppings, and other debris that may accumulate on the panels.

Potential Hail Damage

If you have ever had the unfortunate luck of leaving your car parked outside during an unexpected hail storm, you probably know firsthand the damage that hail can cause to a car. Fortunately, today’s solar panels are built to certain standards that seek to protect against hail damage. The International Electro technical Commission sets the standard for hail resistance in solar panels. According to the Commission, almost all solar panels today have to be able to withstand one inch hail that is travelling at 50 miles per hour. 

Most of the moderate hail storms that occur pose relatively little risk to solar panels. However, in the event of softball-sized solar panels, there is always the chance that the glass covering of panels could become damaged. Similarly, high winds could also potentially cause damage to solar panels, though most manufacturer’s guarantee that their panels can withstand winds up to 90 miles per hour. Hurricane or tornado force windows, however, could potentially cause damage to solar panels (and virtually every other part of a structure as well).

Solar Panels and Temperature

Another common misconception related to solar panels and the weather is that higher temperatures equate to higher energy output while lower, winter temperatures will lead to lower overall energy production. In fact, in many cases the opposite is true. In warmer, southern climates, when the summer sun is high in the horizon and temperatures routinely skyrocket into triple digits, energy production can actually diminish due to the heat. The power created by the PV cells results from voltage and current, and high temperatures have the ability to lower the resting state of the electrons that are found in the PV cell. This can lead to a voltage drop which can theoretically lower the total energy production of solar panels. Many states known for cold winter climates, like Minnesota and Illinois, are currently running successful Community Solar programs. 

During the winter, especially in northern states, there is much less sunlight due to shorter days and the fact that the sun shines low in the northern horizon. Thus, solar power generation will likely suffer, though the frigid temperatures are not to blame.

Fortunately, solar power technology has improved to the point that they can generate electricity in a wide range of climates. Even NASA rovers exploring the dust storms on Mars are able to generate electricity through solar panels. States like New York and Massachusetts, that are known for having long winters with lower sunlight also have some of the most successful solar programs.  Understanding how solar panels react to different weather conditions is important when deciding the best path towards transitioning to this renewable and sustainable energy alternative. 

Community Solar projects can be installed in the best places in a community or region where sunlight exposure is at a maximum. Rooftop solar panel systems, on the other hand, often face obstacles such as shading and improper roof orientation. Clearway Community Solar can help you find a renewable, solar energy option no matter what the climate is like in your region.

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