How Your Solar Panels Work When the Sun Isn't Out
Yes, your solar panels will still generate electricity during cloudy weather. But they're most efficient when it's sunny.
Your solar panels still work even when it's cloudy.
The sun is one of the cleanest and most accessible sources of energy. Solar panels turn the free sunlight we receive every day into electricity to power our homes.
It's a common myth that solar panels don't work at night or when it's cloudy. Solar panels technically still function at night, in fact, but they won't be generating electricity. However, they will still produce electricity during cloudy weather. As long as there's at least a little sunlight, solar panels will generate electricity. Exactly how much depends on the sunlight available.
"The panel is always working. The question is how much electricity comes out of it based on the amount of light," James Fenton, director of the Florida Solar Energy Center, a research institute of the University of Central Florida, told CNET. "You will get close to zero electricity at night, but if there is a little bit of ambient light, sometimes even the reflected moonlight can do it. However, if you were to buy a solar panel, and you actually see the output on your cell phone every day, you'll see that it's close to zero at night."
Can solar panels save you money?
Interested in understanding the impact solar can have on your home? Enter some basic information below, and we’ll instantly provide a free estimate of your energy savings.
Solar adoption is on the rise, with the number of residential installations up 40% in 2021, according to data from the Solar Energy Industries Association.
If you're interested in becoming energy independent, the best way to make a solar purchase is to understand how solar technology works, especially how they generate electricity and whether or not they work on cloudy days or at night.
What are solar panels and how do they work?
Put simply, a solar panel is a device that uses sunlight to generate electricity. There are two main types of solar panel technology: photovoltaic, or PV, and concentrating solar power, or CSP. However, since CSP technology is mainly used in large power plants (and not practical for at-home use), the main focus here is PV solar panel technology. It's what you're likely used to seeing on rooftops.
How does a PV solar panel create electricity from sunlight? A panel contains many layers of photovoltaic cells. These PV cells absorb photons (tiny particles of electromagnetic radiation) from sunlight and create an electric field across the PV cell layers, generating electricity. One PV cell can only produce a small one to two watts, according to the US Energy Information Administration. That's only enough electricity to power a calculator.
This is why solar panels contain a large number of PV cells. Just one solar panel typically generates between 250 to 400 watts of power. The average home solar system has 20 to 25 solar panels, to keep up with how much energy the average American home uses in a year (10,632 kilowatt-hours).
Do solar panels work on cloudy days or at night?
Solar panels will generate electricity as long as there is sunlight for them to absorb. Here's how they function during periods of cloudy weather and at night.
Cloudy weather
Solar panels will still generate electricity during cloudy weather, rain or any other period of indirect sunlight, just not as efficiently. Solar panels are most efficient in direct sunlight and will generate less electricity during cloudy conditions. If you live in an area with a lot of overcast days, your solar panels likely won't be performing at their best on a day-to-day basis.
"Even on a very cloudy or rainy day, you'll get some electricity," Fenton said. "But on real cloudy days, you might only get half as much electricity as you would on a sunny day."
And if you're worried about rain, don't be. Solar panels are waterproof, and rain can actually help clean your solar panels by washing away any dirt, keeping them running efficiently.
Night
Solar panels are called "solar" panels for a reason -- they need to absorb sunlight to generate electricity. Your solar panel will technically always be functioning, but you won't be getting any electricity without some form of sunlight. The only way to power your home with solar energy at night is to install a solar storage system, like a solar battery.
Solar panels won't generate much electricity under the stars.
How do I get power at night if I have solar panels?
With the help of a battery, it's still possible to use solar energy to power your home at night. However, solar batteries are expensive and may not be right for your solar setup. Depending on the type and size of the solar battery, it can cost just as much as your solar panels.
On the other hand, you can stay connected to the power grid and still receive electricity during nighttime and periods of time when your solar panels aren't generating enough power. You might even be compensated for your excess solar energy through a process called net metering.
Solar battery storage
While it's true that solar panels can't work at night due to a lack of sunlight, you can still use solar energy to power your home at night with the help of a solar storage system. The most common form of solar storage is a solar battery, according to the US Department of Energy.
A solar battery allows you to store excess energy generated from your solar panels, which can then be used to power your home at night and during power outages (if you're connected to the grid).
Another benefit of having a solar battery is that you avoid paying higher electricity rates during peak hours. These are hours when more people are at home using electricity, and are usually weekday mornings and evenings. Some utility companies will charge higher electricity rates during peak hours.
The cost of a solar battery is nothing to sneeze at. You can expect to pay anywhere from $6,000 to $16,000 or more for a solar battery, according to SaveOnEnergy, CNET's sister publication. The two main factors affecting the cost of a solar battery are the type of battery and its power capacity. You'll likely get the most out of a solar battery investment if you plan on living off-grid or if you want your home to be 100% powered by clean energy. If you have a solar battery installed, you'll also never have to worry about blackouts, since you'll still have stored solar power to draw from.
Net metering
Going solar doesn't mean you have to be completely reliant on solar energy to have power. Solar batteries are expensive, and they may not be worth the investment for some homeowners. If you choose to stay connected to the grid, your home will draw electricity from the grid during nighttime or periods of limited energy production, so you'll still have power even when your solar panels aren't generating electricity. Any electricity you pull from the grid will be billed from your local utility company like normal.
Experts recommend homeowners invest in energy efficiency around their home before going solar. "If you have a whole home approach to efficiency, you could put solar on top to cap it all off, but you could really lower your bill just by doing efficiency measures, and then you can do solar afterwards to make sure that it's sized appropriately," Andrew Slater, executive director of Energize Delaware, a clean energy nonprofit, told CNET.
Using energy efficient appliances and smart thermostats can help you spend less on power from your local utility company.
Home solar systems connected to the grid can also take advantage of net metering: the process of selling your excess solar energy to the power grid. This means you'll get credits on your bill from your local utility company. Not every state has a net metering policy and some utility companies will compensate you for your energy better than others.
How to get started with solar panels
Interested in buying solar panels for your home? First, you'll need to find a trustworthy solar installer in your area. CNET has already reviewed a few of the best national solar companies out there, but make sure to look into any local installers near you. Local solar installers may offer cheaper prices than some of the national options. To get the best price possible, make sure you get quotes from multiple solar installers.
A trustworthy solar installer will do a home consultation, in which they'll inspect your property to see if your home is right for solar. A good solar installer should also check your roof's condition and your household's energy usage to recommend the best solar system size and equipment for your home. Going solar is a big (and expensive) decision, so take your time, and don't feel like you need to commit to the first solar quote you receive.
Solar Installer Guides
Other Energy Saving Guides
Our Experts
