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Do Solar Panels Work on Rainy Days?

Solar energy is becoming an essential part of the modern energy mix, offering a sustainable and cost-effective solution to meet the world’s growing power demands. Increasing businesses in the commercial and industrial (C&I) sectors are adopting it to lower operating costs, achieve energy independence and meet sustainability goals. As adoption rises, there is also an increase in practical issues or questions particularly about how well solar panels perform in actual conditions. For decision-makers like business owners, EPC contractors and industrial off-takers, reliability is everything. One of the most frequently asked questions is simple yet critical: Do solar panels work in rain?

It’s a common concern, especially in areas with heavy monsoons or frequent cloudy weather. Commercial users often question how solar systems perform when sunlight is limited. Do they still generate power on overcast days? And what happens during long periods of rain?

This blog provides complete guidance on how solar panels perform during rainy or cloudy weather. We’ll explain how solar technology continues to generate power even in low-light conditions, highlight the best panel types for such environments, and share tips to maximize energy output during monsoons. Whether youe are planning a new solar panel installation or looking to improve an existing system, this guide will help you make informed decisions for better performance & long-term returns on your solar investment.

Do Solar Panels Work in the Rain?

One of the most common questions about solar energy is whether solar panels work in the rain or during cloudy weather. It’s a valid concern—especially for regions with long monsoon seasons or frequent overcast skies. The good news? Yes, solar panels do work in the rain—just not at their full potential.

How Rain Affects Solar Panel Performance

Rainy or cloudy weather reduces the amount of sunlight hitting your solar panels. This, in turn, affects the energy output. On rainy days, solar panels typically produce 10% to 25% of their normal capacity. The exact amount depends on how thick the clouds are and how much light filters through.

Even on heavily overcast days, there’s still diffuse sunlight—scattered light that penetrates clouds and allows solar panels to generate power. While it’s not as strong as direct sunlight, modern solar panels are designed to capture both direct and diffuse light.

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What to Expect from Solar Panels in Different Weather?

Heavy Rain/Overcast: Output drops to 10%–25% of capacity.
Light Rain/Dense Clouds: Efficiency can range from 30%–50%.
Partly Cloudy: Performance may reach 50%–70%, depending on conditions.

The Science Behind It: Direct vs. Diffuse Sunlight

To get why panels still work you need to know about the two kinds of sunlight they use:

Direct Irradiance: This is sunlight that comes straight from the sun to your solar panel. It’s what you feel on a bright, clear day and it’s what gives you the most power.
Diffuse Irradiance: This is sunlight that’s been scattered by things in the air like water in clouds, rain and fog. On a cloudy day almost all the light that gets to the ground is diffuse light which is the key to generating solar energy on cloudy days.

Direct sunlight is stronger of course. But modern photovoltaic (PV) cells are great at grabbing this scattered, diffuse light. That’s exactly why solar panel efficiency in cloudy weather never actually hits zero. The technology is built to capture photons from every direction, not just straight from the sun.

What About Battery Storage on Cloudy Days?

Battery storage plays a crucial role in ensuring uninterrupted power during cloudy or rainy days. While solar panels continue to generate electricity even in low-light conditions, their output is lower compared to bright, sunny days. This is where solar batteries come in. When your system produces more energy than you consume—typically on sunny days—the excess power is stored in batteries. During overcast or rainy days, this stored energy can be used to power your home or facility, reducing reliance on the grid. Even when sunlight is limited, solar panels still contribute some energy, helping to top up the battery and extend its usage. With a well-sized battery system, you can enjoy a consistent power supply even when the weather isn’t ideal.

Electricity Generation on Rainy Days

For commercial solar rooftop and industrial solar solutions, understanding both the technical & financial aspects of solar energy during the rainy season is essential. When evaluating solar performance in wet weather, it’s important to break it down into three key areas: how solar panels generate electricity which impacts return on investment. Even during cloudy or rainy days, industrial solar systems continue to produce power due to advanced photovoltaic technology that captures diffuse light. In the commercial solar rooftop space, this means businesses can still reduce grid dependence & maintain energy savings year-round, despite seasonal weather changes.

1. Reduced Efficiency vs. Reduced Fuel

During rainy or overcast conditions, solar panels remain operational; however, their electricity output is notably reduced due to decreased solar irradiance, not a drop in efficiency. The panel’s efficiency rating, which defines its ability to convert incident sunlight into electricity (e.g., 21%), remains unchanged regardless of weather. What varies is the intensity of available sunlight, often declining from approximately 1000 W/m² on clear days to as low as 150 W/m² during heavy rainfall. Consequently, overall power generation decreases. Typically, solar panels generate only 10%–25% of their rated capacity during heavy rain or dense cloud cover, 30%–50% under lighter rain or thick clouds, and 50%–70% on partly cloudy days.

2. The Critical Role of Diffuse Light Capture

Today’s solar panel technology is much better at performing in low-light situations. New developments in cell design especially in monocrystalline and PERC panels help them absorb a wider range of light. This includes the blue and green light that’s more common in diffuse light. Because of this modern commercial solar plants are way more productive on cloudy days than systems from ten years ago. They are built specifically to get the most from solar energy on cloudy days.

3. The Net Impact on Annual Output

For any commercial solar project what matters is long-term performance not day-to-day numbers. A well-designed solar system takes seasonal weather into account right from the start. GSE Renewables uses advanced software and historical weather data tailored to your exact location to optimize solar panel performance.

How Do Solar Panels Hold Up During Thunder and Lightning?

Rain often comes with tougher weather like thunderstorms which brings up real questions about durability and safety. A commercial solar power plant is built to be tough, durable & safe with several layers of protection built right in.

Lightning Protection is Non-Negotiable: A solar panel doesn’t attract lightning more than a regular roof but the whole electrical system needs protection from surges from nearby strikes. A professionally installed commercial solar power plant will have:

Lightning Arrestors: These devices are put in to catch a direct or nearby lightning strike. They safely send that huge amount of electrical energy into the ground keeping it out of the plant’s system.
Surge Protection Devices (SPDs): Found at key spots like inside the inverter and at the main AC panel, SPDs shield sensitive gear from voltage spikes. Spikes can come through utility lines during a storm so SPDs are vital for protecting your inverters, meters and monitoring equipment.
Proper Earthing and Grounding: This is the most important safety feature. The whole mounting frame and all the panel frames are connected and run to a deep, dedicated earth pit. This gives any static charge or fault current a safe path to the ground.

Weatherproof and Durable by Design: Industrial-grade solar parts are made to handle extreme weather.

Solar Panels:Certified panels undergo rigorous testing for mechanical stress, including hail impact and resistance to heavy wind loads
Mounting Structures: These are made from materials that resist rust like anodized aluminum or galvanized steel. They are designed to handle the highest wind speeds in your area even in cyclone zones.
Junction Boxes and Connectors: These parts have high IP ratings like IP67 or IP68. This means they are completely sealed against dust and water.

Solar Panel Performance During Monsoons

In heavy monsoon seasons, the impact on solar energy production is greater but completely predictable. Advanced solar system planning incorporates seasonal weather variations, including prolonged rainfall, into both technical designs and financial projections. This ensures accurate forecasting of annual energy output and return on investment. As a result, lower production during the rainy season is an expected factor not a disruption & does not affect the long-term performance or reliability of commercial & industrial solar installations.

The Cooling Effect Advantage: Heavy clouds and rain lower solar irradiance, but the cooler temperatures during the monsoon can make panels work a little better.Solar panels lose 0.3% to 0.5% of their efficiency for every degree Celsius rise in temperature.In the wet months, cooler temperatures can make up for some of the loss of generation, usually bringing efficiency back up by 2% to 5% compared to the hottest months of summer.But this small gain doesn’t completely make up for the loss in solar input caused by heavy clouds and less sunlight.
Balanced Annual Output: The economics of solar plants are based on how much power they make each year, not how much they make each day. Higher yields during peak rainfall season substantially from March to June when solar prodauction can reach 90%–100% of rated capacity, help make up for the lower yields seen from July to September, when output can decrease by 30%–80% depending on rainfall and cloud cover. Businesses that use net metering can save money by storing extra summer energy as credit. This makes energy costs more even throughout the year, including during the monsoon season.

Annual Output Compensation Strategy

Month/Season	Avg. Daily Output	Cloud Cover	Typical Output Factor	Role in Annual Strategy
Summer (Apr–Jun)	High	Low	90–100%	Peak generation period; builds energy credits.
Monsoon (Jul–Sep)	Low-Medium	Very High	25–50%	Lower generation, factored into annual forecasts.
Post-Monsoon (Oct-Dec)	High	Low-Moderate	70–90%	Strong recovery period with clear skies.
Winter (Jan-Mar)	Moderate-High	Low	60–85%	Good generation with cooler, efficient conditions.

Best Solar Panel for Cloudy Weather

Not all solar panels act the same when it comes to low-light performance. For commercial jobs in rainy areas picking the right solar panels for cloudy climates is key to getting the most power over the year.

Monocrystalline Solar Panels: These panels have a sleek black look and are made from one high-purity silicon crystal. Because the structure is so pure, electrons can move easily which means higher conversion efficiency (usually 18-22%). They work great in low light making them a top pick for maximizing solar energy on cloudy days.
PERC (Passivated Emitter and Rear Cell) Technology: PERC is an upgrade to standard monocrystalline cells. It adds a special layer to the back of the cell. This layer bounces light that passes through the cell back into it giving it a second shot at being turned into power. This is especially good for catching longer wavelengths of light which are more common on overcast days.
Bifacial Panels: Just like the name says, bifacial panels can grab sunlight from the front and the back. They are set up on frames that lift them off the roof or ground. They catch direct and diffuse light from the sky plus light that bounces up from the surface below. On a cloudy day when light is coming from all over bifacial panels can make a lot more power, up to 25% more.
N-type TOPCon and HJT Panels: This is the next wave of high-performance panels. They give you even better efficiency, degrade slower over time and handle heat better. Their advanced cell design is amazing at making power in low-light situations making them a top-tier choice for projects where solar panel performance is everything.

Comparing Solar Panel Output: Sunny vs. Cloudy Days

Understanding how weather impacts solar panel output is essential when planning large-scale commercial or industrial solar installations. Solar irradiance—the amount of sunlight reaching the panels—is measured in watts per square meter (W/m²), & it directly influences energy production. Below is a comparison of solar output under various weather conditions for systems ranging from 150 kW to 5 MW, helping businesses set realistic performance expectations.

Weather Condition	Typical Irradiance (W/m²)	Typical Output (% of Capacity)	Example: 500 kW System Output	Example: 2 MW System Output
Clear, Sunny Sky	900 – 1000+	90% – 100%	450 kW – 500 kW	1,800 kW – 2,000 kW
Partly Cloudy	500 – 700	50% – 70%	250 kW – 350 kW	1,000 kW – 1,400 kW
Overcast / Light Rain	200 – 500	20% – 50%	100 kW – 250 kW	400 kW – 1,000 kW
Heavy Rain / Dark Sky	100 – 200	10% – 20%	50 kW – 100 kW	200 kW – 400 kW

Planning for Consistent Performance

When designing systems above 150 kW up to 5 MW, it’s important to account for seasonal weather changes, especially in monsoon-prone regions. Modern system modeling tools factor in annual irradiance data, ensuring businesses can forecast both energy output and financial ROI accurately. With battery storage and grid support, even rainy days can be managed without disrupting operations.

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Frequently Asked Questions (FAQs)

1. Can solar panels be installed on a rainy day?

Installers can often put up the mounting racks in light rain but all the main electrical work like hooking up panels and inverters has to be done when it’s dry for safety. Most installers will plan their work around any heavy rain.

2. How effective are solar panels on cloudy days?

On a very cloudy day good solar panels can still work at 10% to 30% of their top capacity. If it’s a day with just a few scattered clouds they can often perform at 50% or more. The ability to generate solar energy on cloudy days is better than most people think and the solar panel output in cloudy weather is never zero.

3. Does rain damage solar panels?

No. Good solar panels are made to meet tough international standards and have high IP ratings (IP65 or more). This makes them fully waterproof and built to handle decades of rain, snow, and hail. It’s still a good idea to check for damage after a big storm just in case.

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