Looking up the word "solar" in any dictionary will give you definitions like “related to or derived from the sun” or “using the sun’s energy, especially for heat or electricity.”

It makes sense that solar lights are connected to the sun. But do they really need direct sunlight to work? Do they require it every day? What happens when the skies are cloudy and the sun is hidden?

We often get questions like these, and we’re always happy to help. The good news is: solar panels can still generate power on cloudy days. As long as they have enough battery storage to handle low-light periods, your system should keep running smoothly. Proper sizing is key—let us help you with that!

How Solar Panels Work

Before diving into what happens on overcast days, let’s take a quick look at how solar panels function. According to the U.S. Department of Energy, here's a simple explanation:

“When sunlight hits a solar panel, the photovoltaic (PV) cells absorb the light and convert it into electricity. This process creates an electrical current that can be used to power homes or stored in batteries for later use.”

On sunny days, solar panels receive strong sunlight and store plenty of energy in batteries. However, on cloudy days, the sun’s rays are scattered, reducing the amount of energy available. Still, even on overcast days, solar panels continue to collect some energy.

This doesn’t mean your solar light will fail to operate at night. The battery still charges, just not fully. In regions with frequent cloud cover, proper system design is crucial to ensure reliable performance.

What to Consider When It's Cloudy

The first step is to choose the right size and number of solar panels. Larger panels capture more sunlight, just like a wider bucket collects more rainwater than a narrow one. More efficient and larger panels mean more energy captured.

Next, make sure your panels are properly oriented and angled. In the northern hemisphere, they should face south; in the southern hemisphere, they should face north. Always point them toward the equator for maximum exposure.

Tilt angle also plays a role. At the equator, where the sun is high in the sky, flat panels work well. As you move away from the equator, the sun’s angle becomes lower, requiring a steeper tilt. For example, in Dallas, the ideal tilt is around 30°, while in Minneapolis, it's about 39°.

> A great tool for calculating tilt angles is the World Global Sun Atlas. Feel free to reach out if you need help too.

Incorporating Backup Power

If cloudy days are a concern, using solar lights with higher-capacity batteries is highly recommended. Even though solar panels charge on cloudy days, they might not reach full capacity. That’s why backup power is important—it acts as a buffer when full recharging isn't possible.

Imagine living in Portland, Oregon—a city known for its frequent clouds. On a cloudy day, your battery might only charge to 75%. That’s enough for one night, but if another cloudy day follows, the battery may drop to 50%, then 25%—not enough to power your light at full brightness.

Higher-capacity batteries help by storing extra energy from sunny days for use during cloudy periods. If the battery is too small, it won’t hold enough power to run your system effectively. This can lead to reduced performance or even system failure.

> Want to learn more about batteries and backup systems? Check out this article.

No matter what you've heard, solar lighting can be a reliable and eco-friendly solution—even in areas with frequent cloud cover. Ensuring your system has enough solar collection and battery storage is essential. If you want consistent, dependable lighting regardless of the weather, contact our team today to discuss your project.