Solar panels rely on sunlight to generate electricity. So what happens when clouds roll in?
Solar panels can use direct or indirect sunlight to generate electricity, which means they work in almost all weather conditions. However, solar panels will produce significantly less electricity when it’s cloudy than they will in direct sunlight.
In this blog, we explain how clouds affect solar panels and why residential solar is a good investment for Washington homes despite frequent cloud cover.
How Solar Panels Work
Before we get into how solar panels work when it’s cloudy, it’s helpful to understand how they work in general.
Solar panels use a process called the photovoltaic (PV) effect to turn sunlight into electricity. The photovoltaic effect is a phenomenon through which sunlight is converted into electrical energy when it’s absorbed by a specific material, called a semiconductor. (Silicon is the most common semiconductor used in solar panels.) When the semiconductor is exposed to sunlight, it generates an electrical current. The current is then extracted and used to power your home.
What Happens When It’s Cloudy?
If sunlight is the key to the photovoltaic effect, then how do solar panels work on cloudy days?
It’s simple—clouds rarely block out sunlight entirely. They obscure it, but light still filters down through and around the clouds. Solar panels will absorb any amount of sunlight available and turn it into electricity, so as long as there’s some sunlight, they will generate power. How much power they can produce, however, depends on how much sunlight is available. Solar panels are most efficient in direct sunlight. When there are clouds, they are less efficient and will produce less electricity.
How Much Do Clouds Affect Solar Output?
You’ll generate some electricity with solar panels even on very cloudy, overcast days. But you will see a significant drop in output. Most solar panels will produce about 10-25% of their rated capacity on a cloudy day. At Cascadia Solar, we primarily install Silfab solar panels, which are made in Washington. These panels use state-of-the-art N-type cell technology that’s specifically designed to have high shade tolerance and improved low-light performance.
How Does Rain Affect Solar Panels?
Clouds aren’t great for solar output, but rain is! Rain helps keep your solar panels operating at maximum efficiency by washing away dirt and other grime that blocks sunlight. In wet climates, solar panel maintenance is easier because you won’t have to clean your solar panels as often as you would in a dry or dusty environment. However, we still recommend cleaning your panels about once a year to remove pollen and dirt, which can accumulate on the bottom edges of solar panels and lead to moss growth.
How to Use Solar Power in Cloudy Weather
Since solar panels are less effective in cloudy weather, you may be skeptical about installing solar on your home in Washington, especially if you don’t live in the rain shadow. But Washington has a strong net metering policy, which allows you to benefit from solar power even when your panels are not producing energy. Solar battery storage systems offer similar benefits by allowing you to store solar energy for later use.
Net Metering
Net metering is a billing arrangement between you and your electricity provider. It allows you to export some of the solar power your panels generate to the electric grid in exchange for credit that can be used to buy electricity from the grid when your solar panels are not generating enough power to meet your needs. Your credits roll over month to month until your annual true-up in March. This allows you to bank credits during the long, sunny summer days and use them when the days are shorter and more overcast.
Not every state has a net metering policy and some offer better rate structures than others. Washington State has one of the best net metering policies in the country—all of the utilities within our service area on the Olympic and Kitsap Peninsulas buy back solar power at the full retail rate. That means they credit you for the power you send to the grid at the same rate they charge for it. With 1:1 net metering, you can save significantly more money with solar panels than you would without it.
Solar Battery Storage
A solar battery stores the energy that your solar panels produce so you can use it later. If you install solar panels with battery storage, you can power your home with stored energy when it’s cloudy, at night, or even during a power outage. Solar batteries are a significant investment on top of a solar panel installation, but the added benefits they provide make battery storage worth it for most Washington homes.
Get Started with Solar Panel Installation for Your Home
If you’re interested in installing solar panels for your home on the Olympic or Kitsap Peninsula, Cascadia Solar is here to help. We’ve been installing solar panels since 2008 and, as the solar division of Fredrickson Electric, have been serving local homeowners for over 50 years.
We understand that installing solar panels is a big decision and a significant investment. Our team is here to answer your questions and help you make an informed decision about installing solar panels for your home. We’re a local company that’s committed to doing right by our neighbors, their homes, and the planet, starting with free, no-pressure, no-obligation consultations.
