How Solar Panels Generate Power in Cloudy Weather

A question we hear often is how solar saves for rainy days — and the answer comes down to how modern solar panels are designed to handle diverse weather conditions, not just clear skies.

As fall approaches and the days grow shorter, so does the amount of time the sun shines. Does that mean your solar panels won’t work as well? After all, if their job is to turn light particles into energy, sunlight is a must — so what happens at night and on rainy days?

This is one of the most commonly asked questions by home and business owners when considering a switch to solar power. The good news is that there's no cause for concern, as today's more efficient solar technology has you covered rain or shine.

The key is understanding how solar panels function in low-light conditions. Solar cells — the building blocks of any solar panel system — work by converting light into electricity. They don't require direct sunlight to do this.

On cloudy days, solar panels operate using diffuse light — the light scattered across the sky even when the sun isn't fully visible. Solar panel efficiency does see some reduced efficiency under heavy cloud cover, but solar panels produce a meaningful amount of electricity even on overcast and rainy days.

In fact, solar panels perform surprisingly well in cloudy climates. Germany, one of the world's top solar markets, has weather similar to that of the northeastern U.S., and its solar production numbers are strong.

Regional weather patterns like those in PA, NJ, and DE don't prevent a well-designed solar setup from meeting most of your energy needs throughout the year.

Earning Extra Credit

While solar panels work best on sunny days, they provide the power you need no matter the weather conditions. That’s because they are designed to save for a rainy day.

Just as many people stash away spare change and extra funds when they have them, so do solar panels when they generate power beyond what's needed to meet the demands of your business or home.

This is done by sending extra power generated on sunny days to the power grid for safekeeping.  It’s credited to your account and managed by your solar net meter.

This process — storing excess energy from peak solar production days to offset lower energy generation during cloudy or rainy days — is what makes a solar panel system a year-round solution rather than a fair-weather one.

According to the Solar Energy Industries Association (SEIA), if a home is net metered, the electricity meter will run backwards to provide a credit against the electricity used at night or whenever the demand exceeds the system's output. You are charged only for your "net" energy use, which translates into lower energy bills.

For homeowners who want an added layer of protection, battery storage and solar batteries offer energy storage solutions that hold onto excess energy locally.

This means your solar system can continue to cover your energy needs even after the sun goes down or during extended cloudy periods — without relying on the grid at all. (Related: A Strategic Guide to Residential Energy Storage To Save More)

A Few Tips for Getting the Most from Your Solar Panel System

Here are a few tips to help your solar panel system maintain optimal performance across diverse weather scenarios:

• Panel angle matters. The right panel angle ensures your solar arrays capture as much diffuse sunlight as possible during cloudy weather, not just direct sunlight on clear days.
• Rain acts as a natural cleaning agent. Light rain rinses dust and debris off your solar panels, which can actually improve solar panel performance after a storm by restoring full light absorption capacity.
• High-quality equipment counts. High-quality panels — including bifacial panels, which capture reflected light from below as well as above — are better equipped for energy capture on cloudy and rainy days than lower-grade alternatives. Choosing premium solar panels and high quality equipment from the start pays off over time. (Related: PECO Residential Solar Power Rebate: How TerraSol Energies Makes Going Solar Easy)
• Battery storage extends your reach. Solar batteries store excess energy from sunny hours so your solar system keeps working even when solar panel output drops due to rainy weather or cloud cover. (Related: A Strategic Guide to Residential Energy Storage To Save More)
• Minimal solar panel maintenance goes a long way. Keeping your panels clear of debris and ensuring nothing obstructs sunlight — such as overgrown trees or accumulated grime — helps your solar panels maintain maximum efficiency in all weather conditions.

Don’t let cloudy days hold you back. Let TerraSol Energies design a custom, weather-resilient solar and battery system for your home or business in PA, NJ, or DE. Request a custom solar proposal.

(Related: Going Off-Grid: TerraSol Energies' Remarkable Solar Project in 2022 | PECO Unveils New Solar Incentive for Businesses)

New Jersey (NJ) Leads the Way

If you live in NJ and are thinking about going solar, you couldn't pick a better time to make the move. It's one of only three states to have more than 1 Gigawatt (GWH) of installed solar capacity — and it's just getting started.

The SEIA credits NJ's strong solar market to net metering and a solar renewable portfolio standard, or RPS — a state mandate to increase the use of renewable energy sources.

The federal government is also lending a hand by extending the Solar Investment Tax Credit — a 30% savings for solar systems on residential and commercial properties. Courtesy of the SEIA, here are a few other facts about solar power in NJ:

• At your service are more than 547 solar companies currently employing more than 7,000 people.
• Last year alone, NJ installed 181 Megawatts (MW) of solar electricity capacity, ranking it 10th.
• In 2015, $486 million was invested in solar installations in NJ.
• In the next five years, NJ is expected to install 1,709 MW of solar electric capacity — more than twice the amount installed over the last five years.

(Related: Five Tips for Selecting a Solar Power Panel Installer)

NJ’s regional weather patterns are a good reminder that rainy climates are no barrier to strong solar energy performance.

How much sunlight a region receives matters, but so does how well your solar panel system is designed to make the most of every hour of available light — cloudy days included.

(Related: Rising Utility Costs: Understanding Why PECO Is Raising Electric Rates in 2026)

Work with the Best

TerraSol Energies is a family-run business that has served the Tri-State area (PA, NJ, DE) since 2009. Our solar company is focused on solar electric systems. We have one of the area's most knowledgeable teams of solar specialists.

When you work with us, you can count on making a smooth transition to clean energy. We provide a turnkey approach, quality products and services, professional advice and expertise, and financial flexibility.

Whether your property sees mostly sunny skies or frequent cloudy and rainy days, our team will design a solar panel system built for your specific energy needs and regional weather patterns — using high-quality panels and energy storage solutions that keep your solar production consistent across all seasons.

To find out more about us, our expert partners, and see feedback from our customers, visit our website, or contact us today — and let us show you exactly how solar saves for rainy days for homes and businesses across Pennsylvania, New Jersey, and Delaware.

Frequently Asked Questions

How do solar panels work on rainy days?

Solar panels capture diffuse light—sunlight scattered by clouds and the atmosphere. While efficiency decreases under heavy cover, modern solar cells continue to generate electricity without needing direct sunlight. Additionally, rain washes away dust, improving performance once the sky clears.

What is the 20% rule for solar panels?

The 20% rule generally refers to efficiency and output. High-quality panels typically convert about 20% of available sunlight into power. On a rainy or heavily overcast day, a system’s output usually drops to approximately 10% to 25% of its maximum sunny-day capacity.

What happens if solar panels get rained on?

Rain acts as a natural cleaning agent, rinsing off pollen, dust, and debris that can block sunlight. Because solar panels are waterproof and designed for extreme weather, rain helps maintain long-term efficiency by keeping the surface of the glass clear for better light absorption.

Why do my solar panels trip when it rains?

Systems typically trip during rain due to a ground fault. If there is damaged wiring, a cracked panel, or a loose seal, moisture can enter the electrical path. This triggers a safety shutdown (like a GFCI) to prevent equipment damage or electrical hazards.