Do Solar Panels Work on Cloudy Days?

Written by MiquelM in Energy

Of all the things that homeowners think about when considering solar panels, one of the most prevailing thought is if it would still work on cloudy days. After all, we call it solar panels because it needs the sun to generate energy, right? Well, not quite.

Solar panels work on cloudy days because it doesn’t need direct sunlight to generate energy. It can also use or indirect sunlight, and it can still provide you with the power you need. The only caveat is that it’ll be less efficient on a cloudy day than on a sunny day, but there’s also a workaround to it.

Despite their ability to work on cloudy days, there are still a few things that you need to know about solar panels. We’ll discuss all of them in great detail, including pieces of evidence that prove solar panels still work on cloudy days. Stick around because this article will change your perception of using renewable energy sources.

How Solar Panels Generate Energy

Photovoltaic (PV) panels or solar panels use two kinds of sunlight to generate energy: direct and indirect sunlight. Direct sunlight is ideal because it’s where solar panels can get maximum exposure. However, it still works even on cloudy days through indirect sunlight. That’s because even if clouds block sunlight, it can reflect light and convert it into energy.

However, there’s a significant difference between solar panels’ output on a sunny day and a cloudy day. On average, PV panels generate anywhere from 10% to 25% less energy on a cloudy day. Of course, many other factors can affect this output, but it will still work. In fact, in areas with a typical cloudy, cold temperature like Boston, Milwaukee, New York, San Francisco, and Seattle, solar panels still work really well.

Many people think that solar panels convert heat into energy, but the truth is that it doesn’t need hot weather to work. In fact, solar cells start to degrade if the panels reach a temperature of over 25°C (77°F). Contrary to what people think, PV panels may even be more efficient in San Francisco than in hotter states like Las Vegas.

But other than the weather, a more crucial factor that you need to consider when looking at solar panels is the cost of electricity in your area. For example, New York and San Francisco have high electricity costs, so it’s more important for people in that area to reduce their demand for conventional energy sources.

Even on a cloudy day when panels produce 25% less energy, the savings still provide an excellent ROI. Since solar panels work even with indirect sunlight, location becomes less critical for switching to renewable energy. It’s all about taking as much power you need off-grid as possible and letting your savings pay for the panels’ cost, both in installation and maintenance, while helping the environment.

Aside from PV panels’ ability to use indirect light, their position also plays a significant role in their efficiency to generate power. In fact, solar panels with a wrong angle and position will produce less energy, even on a sunny day, than a properly installed panel on a cloudy day.

More proof that backs its functionality is Germany and Portland. Germany is notorious for its lack of sunlight, and Portland is one of the cloudiest U.S. cities. But did you know that Germany accounts for 25% of the world’s solar power output, while Portland ranks 17th in cities with the best solar capacity in the U.S?

So, weather plays a very insignificant role when using PV panels; you can still use them, and they’ll be very efficient in generating solar power. What’s more important is reducing our dependence on fossil-fuel and using an abundant resource to provide the energy that we need.

Solar Panels During Rainy Days

Another concern for many people looking at solar panels as an alternative energy source is during rainy days. Obviously, there’s less light on a rainy day than a day where clouds only partially block sunlight, right?

But did you know that rainy days can even help you make your solar panels be more energy-efficient? Even on a sunny day, your panels may not be as efficient as they should because of dust and dirt build-up. The more your panels collect dust and dirt, the less efficient they become in harvesting solar power. That’s why anyone must conduct routine clean-ups to ensure that their PV panels are working efficiently.

A rainy day can easily wash these particles away from your panels, making them more efficient in converting sunlight to energy. Since sun rays can still pass through rain and cloud, it can still generate energy. What’s even better is that your panels will be more efficient in generating power after the rain, especially during a sunny day.

The Beauty of Net Metering and Solar Storage

Other reasons why you may still want to consider using solar panels even if you’re in an area that doesn’t get a lot of sunlight are net metering and solar storage. Many states already have laws regarding net metering, which is a way for homeowners to generate more energy than they need, then sell the electricity back into the grid.

If you would like to know how does solar power feed back into the grid, be sure to check our post “How Does Solar Power Feed Back Into the Grid?“.

Suppose you’re in a state with a robust net metering policy. In that case, the excess energy that you generate during sunny days can easily offset the energy that you use when your panels aren’t working (at night) or when it’s not operating at full capacity (cloudy day). Even if your PV panels aren’t generating enough energy, your house won’t run out of power because you’re just buying back the energy you sold to the grid.

Combine this with the fact that PV panels still work regardless of how cloudy or rainy the weather is, making it easier for anyone to switch to renewable energy.

Unfortunately, not all U.S. states have a net metering policy yet. But if you’re in one of these areas, you can still be self-sufficient with proper solar storage. This option allows homeowners to store excess energy into a solar battery bank that can provide the output difference when their panels aren’t operating at full capacity. It’s quite similar to net metering, but instead of selling the electricity back to the grid, you’re storing it for future use.

How to Ensure That You Will Not Run Out of Electricity

Having a robust net metering policy will suffice to cover your consumption on days where your panels aren’t operating at full capacity. But if you want to keep your production and consumption on point, you can talk to your contractor to account for the cloudy days.

Doing this ensures that you’re generating enough power for your consumption during cloudy days and sells back the excess energy on a sunny day back to the grid. You can also calculate the energy savings you can get from using solar panels using EnergySage’s Solar Calculator. It’s a handy tool that you can use to make a more educated decision as to whether solar panels will be beneficial for you or not, based on your current consumption.

Conclusion

The amount of sunlight that your panels get can affect the energy that they generate. But it doesn’t mean that you can’t use them on cloudy or rainy days. In fact, many of the areas that lack sunlight are still on the list of places with the best solar capacity.

A more critical factor that you need to consider is the cost of savings these panels can provide. It would be best to focus on the workarounds that’ll allow you to have the energy you need even during days when your panels aren’t operating at full capacity.

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