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The Sun shines through a tree in a valley near the Russian city of Krasnoyarsk in Siberia. A recent study attributed the severity of the heat wave that swept across Siberia in 2020 to human activity. nikita velikanin / Unsplash

By Michael Allen

Last year was hot. NASA declared that it tied 2016 for the hottest year on record, and the Met Office of the United Kingdom said it was the final year in the warmest 10-year period ever recorded. Temperatures were particularly high in Siberia, with some areas experiencing monthly averages more than 10°C above the 1981–2010 average. Overall, Siberia had the warmest January to June since records began; on 20 June, the town of Verkhoyansk, Russia, hit 38°C, the highest temperature ever recorded in the Arctic Circle.

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dottedhippo / iStock / Getty Images Plus

By Kimberly M. S. Cartier

As the Arctic continues to warm, climate changes cascade into the marine environment. Top predators like polar bears, beluga whales, and narwhals are affected by shifting seasonality and loss of the Arctic sea ice that shapes where they live and what they eat. Moreover, changes in ocean currents alter the transport of toxins like mercury through Arctic waters, which can create health concerns for top consumers in marine food webs.

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MAXSHOT / iStock / Getty Images

Solar panels allow you to harness the sun's clean, renewable energy, potentially cutting your electric bills as well as your environmental footprint. But do solar panels work on cloudy days, or during seasons of less-than-optimal sun exposure? For homeowners who live outside of the Sun Belt, this is a critical question to consider before moving ahead with solar panel installation.

In this article, we'll go over how solar panels work on cloudy days, whether solar panels work at night, and how to ensure you always have accessible power — even when your panels aren't producing solar energy.

How Solar Panels Work on Cloudy Days

Photovoltaic (PV) solar panels can use both direct and indirect sunlight to generate electrical power. This means they can still be productive even when there is cloud coverage. With that said, solar panels are most efficient and productive when they are soaking up direct sunlight on sunny days.

While solar panels still work even when the light is reflected or partially obstructed by clouds, their energy production capacity will be diminished. On average, solar panels will generate 10 to 25% of their normal power output on days with heavy cloud coverage.

With clouds usually comes rain, and here's a fact that might surprise you: Rain actually helps solar panels work more effectively. That's because rain washes away any dirt or dust that has gathered on your panels so that they can more efficiently absorb sunlight.

Do Solar Panels Work at Night?

While solar panels can still function on cloudy days, they cannot work at night. The reason for this is simple: Solar panels work because of a scientific principle called the photovoltaic effect, wherein solar cells are activated by sunlight, generating electrical current. Without light, the photovoltaic effect cannot be triggered, and no electric power can be generated.

One way to tell if your panels are still producing energy is to look at public lights. As a general rule of thumb, if street lamps or other lights are turned off — whether on cloudy days or in the evening — your solar panels will be producing energy. If they're illuminated, it's likely too dark out for your solar panel system to work.

Storing Solar Energy to Use on Cloudy Days and at Night

During hours of peak sunlight, your solar panels may actually generate more power than you need. This surplus power can be used to provide extra electricity on cloudy days or at night.

But how do you store this energy for future use? There are a couple of options to consider:

You can store surplus energy in a solar battery.

When you add a solar battery to your residential solar installation, any excess electricity can be collected and used during hours of suboptimal sun exposure, including nighttime hours and during exceptionally cloudy weather.

Batteries may allow you to run your solar PV system all day long, though there are some drawbacks of battery storage to be aware of:

  • It's one more thing you need to install.
  • It adds to the total cost of your solar system.
  • Batteries will take up a bit of space.
  • You will likely need multiple batteries if you want electricity for more than a handful of hours. For example, Tesla solar installations require two Powerwall batteries if your system is over 13 kilowatts.

You can use a net metering program.

Net metering programs enable you to transmit any excess power your system produces into your municipal electric grid, receiving credits from your utility company. Those credits can be cashed in to offset any electrical costs you incur on overcast days or at night when you cannot power your home with solar energy alone.

Net metering can ultimately be a cost-effective option and can significantly lower your electricity bills, but there are a few drawbacks to consider, including:

  • You may not always break even.
  • In some cases, you may still owe some money to your utility provider.
  • Net metering programs are not offered in all areas and by all utility companies.

Is Residential Solar Right for You?

Now that you know solar panels can work even when the sun isn't directly shining and that there are ways to store your energy for times your panels aren't producing electricity, you may be more interested in installing your own system.

You can get started with a free, no-obligation quote from a top solar company in your area by filling out the 30-second form below.

FAQ: Do Solar Panels Work on Cloudy Days?

How efficient are solar panels on cloudy days?

It depends on the panels, but as a rule of thumb, you can expect your solar panels to work at 10 to 25% efficiency on cloudy days.

How do solar panels work when there is no sun?

If there is literally no sunlight (e.g., at night), then solar panels do not work. This is because the photovoltaic effect, which is the process through which panels convert sunlight into energy, requires there to be some light available to convert.

However, you can potentially use surplus solar power that you've stored in a battery. Also note that solar panels can work with indirect light, meaning they can function even when the sun is obscured by cloud coverage.

Do solar panels work on snowy days?

If there is cloud coverage and diminished sunlight, then solar panels will not work at their maximum efficiency level on snowy days. With that said, the snow itself is usually not a problem, particularly because a dusting of snow is easily whisked away by the wind.

Snow will only impede your solar panels if the snowfall is so extreme that the panels become completely buried, or if the weight of the snow compromises the integrity of your solar panel structures.

Will my solar panels generate electricity during cloudy, rainy or snowy days?

Cloudy days may limit your solar panel's efficiency, but you'll still be able to generate some electricity. Rainy days can actually help clean your panels, making them even more effective. And snowy days are only a problem if the snow is so extreme that the panels are totally submerged, without any part of them exposed to the sun.

A humpback whale, one of the species affected by the Pacific marine heat wave, breaches in Kenai Fjords National Park in the Gulf of Alaska. Kaitlin Thoreson / National Park Service

By Hannah Thomasy

From 2014 to 2016, the Gulf of Alaska experienced the worst marine heat wave of the decade. From single-celled organisms to top predators, practically no level of the ecosystem was left unscathed. During the Pacific marine heat wave, tens of thousands of dead seabirds washed up on beaches, unusually low numbers of humpback whales arrived in their summer habitats, and toxic algal blooms spread along the West Coast of North America.

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A massive methane reservoir beneath the submarine permafrost of the Laptev Sea is leaking. NASA Earth Observatory / Lauren Dauphin

Methane bubbles regularly reach the surface of the Laptev Sea in the East Siberian Arctic Ocean (ESAO), each of them a small blow to our efforts to mitigate climate change. The source of the methane used to be a mystery, but a joint Swedish-Russian-U.S. investigation recently discovered that an ancient gas reservoir is responsible for the bubbly leaks.

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A general view shows the remains of a dam along a river in Tapovan, India, on February 10, 2021, following a flash flood caused by a glacier break on February 7. Sajjad Hussain / AFP / Getty Images

By Rishika Pardikar

Search operations are still underway to find those declared missing following the Uttarakhand disaster on 7 February 2021.

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Researchers are studying jellyfish beach strandings, like this one in Denmark, along the West Coast. SilverSnapper / Getty Images

By Jenessa Duncombe

During some years in the spring, so many jellyfish wash ashore on the beaches of Washington, Oregon, and California that they carpet the sand in thick, gooey mats. The jellyfish Velella velella can pile so high that taken together, they likely equal six and half blue whales' worth of stuff.

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The Chinle Formation at Petrified Forest National Park provides a "living laboratory" for studying the Triassic period. National Park Service

By Ria Mazumdar

Reddish rock formations pervade the American Southwest. Their coloration is associated with the mineral hematite, through which a recent Rutgers University–led study uncovered a powerful link to climate.

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Drone surveillance reveals just how big a contribution sea cucumbers make to reef habitats. treetstreet / iStock / Getty Images

By Hannah Thomasy

On its own, a single sea cucumber may not be very impressive. But get enough of these floppy, faceless creatures together, and they—or, more specifically, their poop—can physically and biochemically reshape a coral reef habitat.

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From this overlook 1,400 feet above the the river, one can understand why the New River Gorge is known by many as the Grand Canyon of the East. Sky Noir Photography / Moment / Getty Images

By Mary Caperton Morton

The only thing "new" about West Virginia's New River Gorge is its national park status: In 2021, the New River Gorge became our latest national park, but in geologic terms, the New River is anything but new. Dating back to the days of the supercontinent Pangaea, it is one of the oldest rivers in the world and one of the few waterways in North America that runs north.

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Botanicals used to flavor spirits, such as absinthe, shown here, grow in alpine regions near glacial ice. Climate warming is now causing this ice to retreat. Moussa81 / Getty Images

By Stacy Kish

Many of the botanicals used in traditional medicines and to flavor spirits, from absinthe to eau de vie, grow in alpine regions near the toes of glacial ice. As the planet warms and glacial ice retreats, this unique environment is changing and altering the diversity of the plant community.

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Houses and wooden debris are shown in flood waters from Hurricane Katrina Sept. 11, 2005 in New Orleans, Louisiana. Jerry Grayson / Helifilms Australia PTY Ltd / Getty Images

By Eric Tate and Christopher Emrich

Disasters stemming from hazards like floods, wildfires, and disease often garner attention because of their extreme conditions and heavy societal impacts. Although the nature of the damage may vary, major disasters are alike in that socially vulnerable populations often experience the worst repercussions. For example, we saw this following Hurricanes Katrina and Harvey, each of which generated widespread physical damage and outsized impacts to low-income and minority survivors.

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Ganga river pollution in Kolkata, India on October 2019. Indranil Aditya / NurPhoto / Getty Images

By T. V. Padma

Studies increasingly point to the presence of pharmaceutical and personal care products in urban stretches along the Ganges River, which originates pristine in the Himalayas but is heavily polluted with industrial effluents and domestic sewage when it empties into the Bay of Bengal.

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