We all know that solar panels use sunlight to generate electricity – but what happens during cloudy or rainy days? The short answer is: as long as there’s still sunlight filtering through, solar panels can still produce power during rain and cloudy weather. That said, they won’t produce the same amount of electricity as they would on a sunny day.
With more than 300 sunny days per year in Arizona, cloudy and rainy days aren’t something we have to worry about too often. But they still happen, and you might be wondering how these days can affect your solar panel’s production and energy savings.
In this article, we’ll share all you need to know about how solar panels work when it’s raining or cloudy, and what you can do to keep them performing at maximum efficiency.
How solar panels turn sunlight into electricity
Before we start looking at how solar panels work on rainy or cloudy days, let’s explore the process of converting sunlight into power.
Solar panels are made from photovoltaic (PV) cells, which are usually silicon or another semiconductor material. These PV cells convert solar radiation (in the form of sunlight) into electricity through a process called the photovoltaic effect.
When sunlight hits a PV cell, the light particles – known as photons – transfer their energy to the silicon atoms. This energy knocks electrons loose from their atoms and allows them to move more freely. The movement of these electrons creates an electric current, which flows through the cell and is captured as usable electricity.
The electricity generated by solar panels is direct current (DC). Since most homes and businesses use alternating current (AC), an inverter is used to convert DC into AC power that’s compatible with household appliances and the electricity grid.
Solar panels can generate electricity from two types of sunlight: direct light and diffuse light:
- Direct light: This type of sunlight hits the panels directly, producing the maximum amount of electricity.
- Diffuse light: This is when sunlight is scattered (‘diffused’) in the atmosphere, like on cloudy or rainy days. Solar panels can still produce electricity, as long as the sun is reaching their surface, but at reduced efficiency compared to sunny days.
Note that solar panels don’t rely on the sun’s heat to work, only light. This means they can operate at the same efficiency all year round, as long as there’s sunlight.
Keep Reading: How Does Solar Power Work?
What happens to solar panels when it’s cloudy or raining?
Solar panels produce the most amount of electricity when exposed to direct sunlight, but they still work during cloudy or rainy days – just not as efficiently as usual. Even with reduced efficiency, there are many examples of solar panels in cloudy or rainy climates that produce enough electricity to meet most household needs and reduce electricity bills.
How solar panels work on cloudy days
On cloudy days, solar panels perform at reduced efficiency because there’s less sunlight available to convert into electricity. However, there still is some sunlight, which means solar panels can continue generating power. It all depends on how dense the cloud cover is.
Partially cloudy days, which is when clouds cover 37.% to 62.5% of the sky, sunlight still filters through and reaches the surface of solar panels. This means your panels may still generate enough electricity to meet your needs – depending on other factors such as outside heat, and how much energy your AC might be needing at the time.
Fully overcast days, with heavier cloud cover, usually means less solar power generation since more clouds are blocking the sunlight. Thankfully, these days are less common than partially cloudy days – especially in Arizona where we’re lucky to enjoy more than 300 sunny days each year.
To make things a little interesting, cloudy days can sometimes even increase solar production thanks to something called the ‘cloud lensing’ effect. When this happens, clouds act as a lens that concentrates sunlight in a specific direction. If that sunlight reaches your solar panels, they can produce a lot of electricity. This is a relatively rare occurrence.
That said, in general, solar panels won’t operate as efficiently or produce as much electricity on cloudy days as they would during full sun.
How solar panels work on rainy days
Rain can temporarily reduce solar energy production, but it also brings an unexpected benefit – cleaning! Solar panels gather dust, dirt, and debris over time, which can block sunlight and reduce efficiency. Rain naturally washes much of this dust and debris away, leaving your solar panels ready to absorb more sunlight.
But can solar panels generate power on rainy days? Just like cloudy days, it all depends on how much sunlight is filtering through. Sometimes, solar radiation can make its way through the rain and allow for energy production. One way to check if your panels are still producing electricity on a rainy day is to check for shadows. If you can see shadows, it means there’s some sunlight and your panels are still generating power – although at reduced efficiency.
How different weather conditions affect solar panels
Modern solar panels are built with advanced technologies that can withstand a range of different weather conditions and temperatures. If you’re curious about how solar panels respond to different weather conditions, keep reading.
Rain
As mentioned earlier, rain washes away dirt, dust, and debris from solar panels – which can actually improve their efficiency. While you might experience temporary dips in energy production during periods of heavy rain, the long-term maintenance benefit will likely outweigh this minor drawback.
Snow
If you live in the northern part of the state, you might experience some snow during the winter. Solar panels can still generate power on snowy days, as long as there’s visible sunlight. Like rain, it all depends on the amount of cloud coverage. Thick, heavy clouds are likely to reduce energy production more.
Unlike rain, snow can accumulate over your solar panels and block sunlight. Light dustings of snow aren’t usually a problem – this will often be blown off by wind or melt off the next day but if you have heavy snowfall, you might need to call in a professional to clear your solar panels. Leaving snow to accumulate over your solar panels can significantly affect energy generation and potentially cause damage.
Extreme temperatures
Solar panels are built with durable materials that can handle a wide range of temperatures. In extremely high heat, however, solar panels can experience slight dips in energy production. This minor loss is more than made up for by overall sun exposure throughout the year.
See: Maximizing Solar Efficiency in Extreme Heat: A 2024 Guide
In freezing cold temperatures, solar panels continue to generate electricity. Remember, panels don’t need heat to work – only sunlight.
Wind
Strong winds only pose a risk to solar panels if they’re not properly installed. Solar panels need to be securely mounted according to local building codes using mounting systems that are specifically engineered to keep them secure during high winds. This is why it’s so important to hire a professional, reputable solar company that understands the local climate and weather conditions, and has sourced products designed to meet the needs of the area.
Learn More: How to Choose the Best Solar Installer for Your Home
Humidity
High humidity can cause corrosion in solar panels over the long-term. Thankfully, humidity isn’t something we have to worry about much in Arizona. In any case, choosing solar panels made with corrosion-resistant materials can help prolong their lifespan in humid climates.
Smoke & smog
Wildfire smoke, smog, or air pollution can all block sunlight and reduce solar panel efficiency. During California’s 2020 wildfires, for example, peak-hour solar production dropped by 10-30% due to heavy smoke.
Solar panels will still continue to produce electricity as long as some sunlight can shine through, but if you live in a region prone to wildfires it may be worth adding a solar battery storage system to maintain power during periods of heavy smoke and power outages.
Hail
Although hailstorms are rare, most solar panels are rigorously tested to withstand the impact of hailstones – including industry-standard tests where ice balls are shot at panels at high speeds. Solar panels are made from tempered glass, also known as toughened glass, which is highly durable and resistant to impact.
That said, severe hailstorms can still pose a risk to solar panels. This risk can be mitigated by installing solar panels at an angle, which many of them already are for optimal sunlight exposure.
Read More: Solar Panel Direction: What is the Best Angle?
Thunderstorms
During thunderstorms, solar panels are typically safe and won’t attract lightning more than any other roof structure might. That said, proper grounding and surge protection is essential to prevent electrical damage from nearby lightning strikes.
These safety features are included in most modern solar systems, but proper installation is needed to ensure that systems have been connected correctly, with safety in mind. Regular inspections by a certified technician will also ensure they’re still effective and functioning properly.
5 tips to keep solar panels efficient in cloudy or rainy weather
No matter where you live, you’re likely to deal with some cloudy or rainy days at least a few times a year. To keep your solar panels working efficiently during those periods, consider the tips below:
1. Opt for quality panels with high efficiency ratings
Not all solar panels are created equal. Solar panels with higher efficiency ratings – at least 19% and above – are better at converting sunlight into electricity. When we talk about efficiency, we’re referring to the percentage of sunlight that’s converted into electricity. So a panel with 22% efficiency will be converting 22% of the sunlight that reaches it into electricity.
While they might cost a little more upfront, these panels will perform better in low-light conditions (and in general) which can maximize your energy production and increase your overall return on investment. Plus, using a higher efficiency panel generally means you will need to purchase fewer panels to achieve your production goal, helping to reduce system cost.
2. Install more solar panels
Adding more solar panels increases your solar system’s total output. On overcast days, the additional power generation can make up for the reduced sunlight and ensure your household still meets its energy needs. A reputable installer can work with you to design an appropriately sized solar panel system for your energy needs and location.
See: How Many Solar Panels Do I Need?
3. Invest in solar battery storage
Home battery systems store excess electricity generated by your solar panels for you to use at night or on cloudy days. This is one of the best ways to ensure a constant, reliable source of solar energy all year round and get the most out of your investment. You can even use solar power during a power outage!
4. Keep your panels shade-free
The more sunlight that reaches your solar panels, the more power they can generate. To keep your panels functioning at their best, make sure there’s no shading over their surface at any point during the day. Trim surrounding trees and avoid installing your panels in areas that get shade. This ensures they work at maximum efficiency even during sunny days.
5. Use smart monitoring tools
Most solar systems these days come with apps or monitoring devices that provide real-time data on power production and panel performance. Keep an eye on these monitoring systems to recognize when solar panels might be underperforming and spot any potential issues before they become bigger problems.
Summary: Do solar panels still work when it’s raining or cloudy?
Solar panels are designed to capture as much light as possible, even on cloudy or rainy days without direct sunlight. While they might operate at reduced efficiency on these days, panels can still produce enough electricity to meet household needs. Consider this: Germany, a country known for its cloudy weather, is one of the world’s leading adopters of solar energy. This shows us that solar panels can still be a worthwhile investment – even in regions with less sunlight.
In Arizona, our abundance of sunny days vastly outnumber the few rainy or cloudy days we experience. This means adopting solar energy can still be worth the investment, as long as your home meets other requirements like minimal shading, proper roof orientation, and sufficient space for a solar array.
If you’re not sure whether solar is worth it for you, don’t hesitate to contact our team for a free solar consultation. We’ll be happy to provide advice customized to your home’s location and energy needs, and provide a no-obligation cost estimate. Call us now on 480-576-5693.