Looking up the word "solar" in a dictionary will give you definitions like "related to the sun" or "using sunlight to generate power." But when it comes to solar lights, many people wonder: do they actually need direct sunlight to work? What happens when it's cloudy or rainy?

These are common questions we hear, and the answer is simple: yes, solar lights can still function on cloudy days. Solar panels can absorb diffuse light, even if it’s not as strong as on a sunny day. As long as your system has enough battery storage to handle low-light periods, your lights will keep working.

Proper solar sizing is key. It’s not just about how much sun you get—it’s also about how much energy your batteries can hold. If you're in an area with frequent cloud cover, it's important to plan ahead to ensure your system remains reliable.

How Solar Panels Work

Before diving into cloudy days, let’s take a quick look at how solar panels operate. According to the U.S. Department of Energy (DOE), when sunlight hits a solar panel, the photovoltaic (PV) cells absorb the energy and convert it into electricity. This process allows the system to store power for later use.

On sunny days, solar panels collect a lot of energy, which is then stored in batteries. On overcast days, less sunlight reaches the panels, so less energy is generated. However, this doesn’t mean your lights will stop working. Even on cloudy days, the battery continues to charge—just at a slower rate.

In areas with frequent cloud cover, it's crucial to ensure your system has enough capacity to last through multiple low-light days. Otherwise, your lights might not have enough power to stay on all night.

What You Can Do on Cloudy Days

The first step is to choose the right size and number of solar panels. Larger panels can capture more energy, even on overcast days. Think of it like using a wide bucket instead of a small one during rain—more surface area means more collection.

Next, optimize the orientation and tilt of your panels. In the northern hemisphere, panels should face south; in the southern hemisphere, they should face north. The tilt angle also matters. At the equator, flat panels work well, but as you move away from the equator, you’ll need to increase the tilt to capture more sunlight.

For example, in Dallas, the ideal tilt is around 30°, while in Minneapolis, it’s closer to 39°. A great tool to help determine the best tilt is the World Global Star Atlas website—or feel free to reach out to us for guidance.

Adding Backup Power

If you’re in an area that often experiences cloudy weather, consider using solar lights with larger battery capacities. These systems act as a buffer, storing extra energy from sunny days to use when the sun isn't shining.

Imagine living in Portland, Oregon—a place known for its gray skies. On the first cloudy day, your battery might only charge to 75%. That’s enough for one night, but if the next day is also cloudy, the battery might drop to 50%, and so on. Without backup power, your lights may start to dim or turn off completely.

Higher-capacity batteries help by storing energy collected on sunny days for use when solar input is low. If your batteries are too small, they won’t be able to support the system for long periods without sunlight, leading to reduced performance or system failure.

Want to learn more about batteries and backup solutions? Check out our detailed guide here.

Solar lighting can be a reliable and eco-friendly option—even in places with frequent cloud cover. The key is proper planning, including sufficient solar panel size and battery capacity. If you want consistent, dependable lighting no matter the weather, contact our team today to discuss your project.